HCPCS
J1561
1 unit = 500 mg
Phase 1
Identify what you're billing
Confirm the 500 mg unit basis, the indication-specific dose, the route (IV vs SC), and which dual-licensed brand was infused.
The 500 mg unit-basis trap CMS HCPCS verified May 2026
J1561 is one of the IVIG class codes that bills at 500 mg per unit. Most J-codes default to 1 mg per unit; many IVIG-aware billers default to 1 g per unit. Both shortcuts are wrong for Gamunex-C / Gammaked.
| Dose (g) | Dose (mg) | Correct units (÷ 500) | Wrong: 1 mg/unit (× 1,000) | Wrong: 1 g/unit |
|---|---|---|---|---|
| 1 g | 1,000 mg | 2 units | 1,000 units (500x over) | 1 unit (2x under) |
| 5 g | 5,000 mg | 10 units | 5,000 units | 5 units |
| 10 g | 10,000 mg | 20 units | 10,000 units | 10 units |
| 20 g | 20,000 mg | 40 units | 20,000 units | 20 units |
| 35 g (typical PI maint.) | 35,000 mg | 70 units | 35,000 units | 35 units |
| 50 g | 50,000 mg | 100 units | 50,000 units | 50 units |
| 70 g (1 g/kg, 70 kg CIDP maint.) | 70,000 mg | 140 units | 70,000 units | 70 units |
| 100 g | 100,000 mg | 200 units | 100,000 units | 100 units |
| 140 g (2 g/kg, 70 kg CIDP load) | 140,000 mg | 280 units | 140,000 units | 140 units |
Conversion shortcut for J1561: grams × 2 = units. (Because 500 mg = 0.5 g,
each gram = 2 units.) A 35 g dose is 70 units. A 1 g/kg dose for a 70 kg patient (70 g) is 140 units.
A 2 g/kg loading dose for a 70 kg CIDP patient (140 g) is 280 units. Always document the conversion in
the chart so an auditor can reproduce the unit count from the calculated mg dose.
Why CMS uses 500 mg per unit for IVIG
IVIG dosing is universally weight-based and runs in tens of grams per dose — orders of magnitude larger than the per-mg J-code defaults built for biologics like rituximab or pembrolizumab. CMS settled on 500 mg as the IVIG unit denominator because it produces a manageable two- to three-digit unit count for typical doses (10–300 units per infusion) and aligns with the gram-multiple vial sizes IVIG manufacturers ship. Most IVIG codes follow the same 500 mg pattern (J1459 Privigen, J1568 Octagam, J1569 Gammagard Liquid, J1572 Flebogamma, J1599 unclassified IVIG, etc.); subcutaneous IG codes use a different 100 mg basis (J1559 Hizentra). Always verify per HCPCS descriptor.
Dual-brand licensing — Gamunex-C (Grifols) + Gammaked (Kedrion) FDA + manufacturer verified May 2026
Gamunex-C and Gammaked are the same product, sold by two different manufacturers under the same HCPCS code. This is unusual in the IVIG class and creates a few biller-specific things to know.
| Gamunex-C | Gammaked | |
|---|---|---|
| Manufacturer / labeler | Grifols Therapeutics | Kedrion Biopharma |
| NDC labeler segment | 13533 | 76125 |
| HCPCS code | J1561 | J1561 (same) |
| HCPCS descriptor | "Inj, immune globulin, (gamunex-c/gammaked), non-lyophilized (e.g. liquid), 500 mg" — both brands explicitly named in the descriptor | |
| Active ingredient | Immune globulin intravenous (human), 10% caprylate/chromatography purified — identical | |
| Stabilizer | Glycine | |
| Vial sizes | 1 g, 2.5 g, 5 g, 10 g, 20 g, 40 g single-dose vials | |
| FDA-approved indications | PI, ITP, CIDP (and SC route in PI) | |
| Patient assistance | Grifols PathConnect (1-855-477-2672) | Kedrion KedPlasma Patient Assistance |
| Original FDA approval | Aug 2003 (as Gamunex); 2010 relabel as Gamunex-C | 2011 (Kedrion dual-license) |
How dual-licensing works in practice: Grifols manufactures the product. Kedrion has an
independent license to sell the same product under a different brand name. Some hospital and infusion-center
contracts are with Grifols (so the patient receives Gamunex-C-labeled vials); others are with Kedrion (so the
patient receives Gammaked-labeled vials). The HCPCS code on the claim is J1561 in both cases. The NDC must
match the labeler whose vial was actually drawn — verify with the dispensing record.
Payer brand-preference patterns:
- Some payers contract with Grifols and prefer Gamunex-C (or require it on the PA).
- Some payers contract with Kedrion and prefer Gammaked.
- Some payers treat them as fully interchangeable and accept whichever labeler the site stocks.
- For CIDP specifically, many payers prefer the Gamunex-C / Gammaked pair (vs other IVIG brands) for the FDA CIDP indication and historical evidence base.
Dosing per indication — PI / ITP / CIDP FDA Gamunex-C label verified 2025–2026
Three FDA-approved indications, three completely different dosing regimens. The biller must match the indication ICD-10, the dose calculation, and the schedule before billing.
| Indication | Loading / induction | Maintenance | Frequency | Target / monitoring |
|---|---|---|---|---|
| Primary humoral immunodeficiency (PI) — IV Adults + children ≥2 yr |
n/a (no separate loading) | 300–600 mg/kg per dose IV | Every 3–4 weeks | Adjust to maintain IgG trough 500–1,000 mg/dL (target individualized to patient's response and infection history) |
| Primary humoral immunodeficiency (PI) — SC Adults + children ≥2 yr |
Initial SC dose = 1.37 × previous IV monthly dose ÷ 4 (weekly) | 100–200 mg/kg/week SC | Weekly | IgG trough monitoring; rotate SC infusion sites |
| Chronic ITP Adults + children ≥3 yr |
1 g/kg/day × 1–2 days | Per platelet response — repeat as needed | Episodic / response-driven | Platelet count & clinical bleeding control |
| CIDP Adult only — FIRST FDA-approved IVIG for CIDP (2008) |
2 g/kg over 2–4 days (loading) | 1 g/kg over 1–2 days | Every 3 weeks | INCAT, MRC sum score, grip strength — reauthorize on continued benefit |
Worked dose & unit calculations
PI maintenance, 70 kg patient, 500 mg/kg IV q4wk:
Dose: 500 mg/kg × 70 kg = 35,000 mg = 35 g
Vials drawn: 1 × 20 g + 1 × 10 g + 1 × 5 g = 35 g (matched, no waste)
Units billed: 35,000 / 500 = 70 units (J1561 + JZ)
CIDP loading, 70 kg patient, 2 g/kg over 4 days:
Total dose: 2 g/kg × 70 kg = 140 g (split ≈ 35 g/day × 4 days)
Per-day units: 35,000 / 500 = 70 units/day
Units billed: 280 units total across 4 dates of service
CIDP maintenance, 70 kg patient, 1 g/kg q3wk:
Dose: 1 g/kg × 70 kg = 70 g
Vials drawn: 1 × 40 g + 1 × 20 g + 1 × 10 g = 70 g (matched, no waste)
Units billed: 70,000 / 500 = 140 units (J1561 + JZ)
ITP induction, 60 kg patient, 1 g/kg/day × 2 days:
Per-day dose: 1 g/kg × 60 kg = 60 g
Vials drawn: 1 × 40 g + 1 × 20 g = 60 g (matched, no waste)
Units per DOS: 60,000 / 500 = 120 units × 2 dates of service
Weight-based dosing rarely matches vial sizes exactly. The examples above use round 70 kg
and 60 kg weights. Real patient weights (e.g., 67.4 kg) almost never hit a clean integer vial combination
— expect partial-vial waste and plan for JW (see modifiers). Gamunex-C /
Gammaked has the smallest vial size in the IVIG class (1 g) which can help reduce waste at small body
weights or pediatric doses.
CIDP — Gamunex-C's signature indication FDA + AAN/EAN/PNS verified May 2026
Gamunex-C was the first IVIG product approved by the FDA specifically for the treatment of CIDP. This matters for biller documentation and payer coverage decisions.
The FDA approved Gamunex (now Gamunex-C) for CIDP in September 2008, based on the ICE trial (Immune Globulin Intravenous Caprylate / Chromatography purified, in CIDP Efficacy) — the largest randomized, placebo-controlled trial of IVIG in CIDP, published in Lancet Neurology (2008). Gamunex-C remains the IVIG with the deepest CIDP evidence base. Privigen (J1459) received CIDP approval in 2017, providing a second labeled IVIG choice; Panzyga (no separate J-code, bills under unclassified) received CIDP approval in 2021. Most other IVIG products are used in CIDP off-label.
Biller takeaway for CIDP: when the patient's indication is CIDP and the payer has a brand
preference, Gamunex-C / Gammaked is one of the IVIGs most commonly named on the preferred list because of the
FDA CIDP indication. Document the indication ICD-10 (G61.81) and the rationale (FDA-labeled, evidence-based)
in the PA submission. This is meaningfully easier ground than off-label IVIG appeals.
What CIDP PA documentation typically requires
- Diagnosis confirmation: neurologist documentation of clinical course (progressive or relapsing weakness lasting >2 months); EMG/NCS findings consistent with demyelination (slow nerve conduction velocities, conduction block, prolonged distal latencies, F-wave abnormalities); exclusion of alternative diagnoses (genetic neuropathies, paraproteinemic neuropathies, metabolic causes).
- Baseline functional scoring: INCAT (Inflammatory Neuropathy Cause and Treatment) disability score, MRC (Medical Research Council) sum score, grip strength — for both initial PA documentation and reauthorization comparison.
- Loading vs maintenance documentation: initial PA usually approves both the 2 g/kg loading and the q3wk 1 g/kg maintenance; reauthorization requires evidence of clinical benefit (improved or maintained INCAT/MRC scores).
- Failed alternatives: some payers require corticosteroid trial or plasmapheresis trial before IVIG; many payers waive this for severe CIDP or contraindications to alternatives.
Gamunex-C CIDP dosing — the standard regimen
- Loading: 2 g/kg total, divided over 2–4 consecutive days (e.g., for a 70 kg patient: 140 g total = 280 J1561 units, typically split as 70 g/day × 2 days or 35 g/day × 4 days).
- Maintenance: 1 g/kg every 3 weeks (for a 70 kg patient: 70 g per cycle = 140 J1561 units; typically 17 cycles per year).
- Annual drug volume (70 kg patient on maintenance): 70 g × 17 cycles = 1,190 g = 2,380 J1561 units per year, plus the loading dose.
IV vs SC route — Gamunex-C is approved for both FDA verified May 2026
Gamunex-C is one of the few IVIG products with both intravenous and subcutaneous FDA labeling for primary immunodeficiency. Same product, two routes — very different billing pathways.
| Gamunex-C IV | Gamunex-C SC (PI only) | |
|---|---|---|
| HCPCS code | J1561 | J1561 (same) |
| Unit basis | 1 unit = 500 mg | 1 unit = 500 mg |
| Indication coverage | PI, ITP, CIDP | PI only (per FDA label) |
| Dose | 300–600 mg/kg q3–4wk (PI); 1 g/kg q3wk (CIDP); 1 g/kg/day (ITP) | 100–200 mg/kg/week (PI) |
| Initial SC conversion | n/a | 1.37 × (previous IV monthly dose) ÷ 4 = first weekly SC dose |
| Admin time | 2–6 hr per IV infusion | 1–2 hr per SC infusion (multiple sites simultaneously via pump) |
| Admin CPT | 96365 + 96366 (therapeutic IV) | 96369 + 96370 + 96371 (SC infusion, with pump) |
| Site of care | HOPD / AIC / home infusion | Often self-administered at home after training |
| Pre-medication need | Common (acetaminophen + diphenhydramine) | Often unnecessary or minimal |
| Systemic reaction risk | Higher | Lower (slower absorption) |
| Local site reaction risk | Lower | Higher (injection site inflammation) |
Billing nuance for Gamunex-C SC: the same J1561 HCPCS code applies for IV and SC routes,
but admin coding differs. Use the SC infusion family (
96369 initial up to 1 hour with pump,
96370 each additional hour, 96371 additional pump set-up) for SC Gamunex-C.
Some payers may want the route documented in the PA — SC vs IV affects the site-of-care decision and
the patient's self-administration training requirements. Many payers prefer SC for stable chronic PI patients
because it avoids repeated IV access and chair time.
Note: dedicated SC immune globulin products (Hizentra J1559 CSL Behring, Cuvitru, Cutaquig
Octapharma, Xembify Grifols, HyQvia Takeda) have their own HCPCS codes and are not interchangeable with
Gamunex-C SC for billing. If the patient is transitioning from Gamunex-C IV to a dedicated SC IG product,
re-PA is required and the J-code on the claim changes.
Infusion rate titration FDA Gamunex-C label, infusion rate tables verified 2025–2026
IVIG must be started slow and titrated up by patient tolerance. Total infusion time per dose typically runs 2–6 hours, which drives chair time and 96366 add-on units.
| Indication | Starting rate | Titration | Maximum rate | Typical total time |
|---|---|---|---|---|
| PI (IV) | 1 mg/kg/min (0.01 mL/kg/min) | If tolerated, increase every 30 min | 8 mg/kg/min (0.08 mL/kg/min) | 2–4 hr |
| ITP | 1 mg/kg/min (0.01 mL/kg/min) | If tolerated, increase every 30 min | 8 mg/kg/min (0.08 mL/kg/min) | 3–6 hr (high dose) |
| CIDP | 2 mg/kg/min (0.02 mL/kg/min) | If tolerated, increase every 30 min | 8 mg/kg/min (0.08 mL/kg/min) | 3–6 hr (loading split over multi-day) |
| PI (SC) | 20 mL/hr/site | If tolerated, increase per label | 30 mL/hr/site (or per tolerance) | 1–2 hr per weekly session |
Why titration matters for the biller. Total chair time — not the calculated maximum-rate
time — determines how many
96366 add-on hours are billable. A patient on Gamunex-C at full
titration may infuse a 35 g dose in about 90 minutes; the same patient in their first month, still titrating,
may need 4–5 hours. Chart-document actual infusion start and stop times. Slow titration on first
infusions, suspected reactions, or known prior reactions justifies additional 96366 units.
Dose-fractionation for high-dose CIDP & ITP
High loading doses (e.g., CIDP 2 g/kg or ITP 1 g/kg) are typically split across 2–5 consecutive days to keep per-day infusion volume tolerable, especially in patients with cardiovascular or renal risk factors. Each daily infusion bills as a separate date of service with its own admin codes (96365 + 96366 × N) and its own J1561 unit count.
NDC reference — Grifols (13533) + Kedrion (76125) FDA NDC Directory verified May 2026
Pad to 11 digits with a leading zero in the appropriate segment for CMS-1500 Box 24A. Use N4 qualifier and report units of measure (ML) and quantity drawn from the vial. Match the NDC labeler segment (13533 Grifols vs 76125 Kedrion) to the brand actually drawn.
| Brand | Vial size | Volume | NDC labeler — representative |
|---|---|---|---|
| Gamunex-C (Grifols) | 1 g | 10 mL | 13533-800-12 (verify current package) |
| Gamunex-C (Grifols) | 2.5 g | 25 mL | 13533-800-15 (verify current package) |
| Gamunex-C (Grifols) | 5 g | 50 mL | 13533-800-20 (verify current package) |
| Gamunex-C (Grifols) | 10 g | 100 mL | 13533-800-24 (verify current package) |
| Gamunex-C (Grifols) | 20 g | 200 mL | 13533-800-71 (verify current package) |
| Gamunex-C (Grifols) | 40 g | 400 mL | 13533-800-78 (verify current package) |
| Gammaked (Kedrion) | 1 g | 10 mL | 76125-800-01 (verify current package) |
| Gammaked (Kedrion) | 2.5 g | 25 mL | 76125-800-02 (verify current package) |
| Gammaked (Kedrion) | 5 g | 50 mL | 76125-800-05 (verify current package) |
| Gammaked (Kedrion) | 10 g | 100 mL | 76125-800-10 (verify current package) |
| Gammaked (Kedrion) | 20 g | 200 mL | 76125-800-20 (verify current package) |
| Gammaked (Kedrion) | 40 g | 400 mL | 76125-800-40 (verify current package) |
11-digit NDC required on most claim forms. Pad labeler-product-package to 5-4-2 segments.
Use
N4 qualifier in CMS-1500 Box 24A shaded area with unit of measure (ML) and quantity actually
drawn. Critically: verify NDCs against the Grifols / Kedrion billing guides and the FDA NDC
Directory at billing time — package configurations occasionally change, and the labeler segment
(13533 vs 76125) must match the brand actually administered.
Why match the labeler: if the site stocks Gamunex-C (Grifols) but the claim NDC is the
Kedrion 76125 labeler, the claim is technically inaccurate even though the J-code is correct. NDC audits
compare labeler segments against purchase records. Standardize the NDC in the EHR to the brand contracted
by your facility.
IVIG brand interchangeability Verified May 2026
IVIG products are NOT interchangeable for billing — with the unique exception of Gamunex-C and Gammaked, which share J1561. Each other IVIG brand has its own HCPCS, NDC, and ASP, and payer brand mandates differ widely.
| HCPCS | Brand | Mfr | Concentration | Stabilizer | Unit basis | FDA CIDP? |
|---|---|---|---|---|---|---|
J1561 |
Gamunex-C | Grifols | 10% liquid | Glycine | 500 mg | Yes (2008, first) |
J1561 |
Gammaked | Kedrion | 10% liquid | Glycine | 500 mg | Yes (dual-license w/ Gamunex-C) |
J1459 |
Privigen | CSL Behring | 10% liquid | L-proline | 500 mg | Yes (2017) |
J1569 |
Gammagard Liquid | Takeda / Baxalta | 10% liquid | Glycine | 500 mg | No (off-label use) |
J1568 |
Octagam (5% & 10%) | Octapharma | 5% / 10% liquid | Maltose | 500 mg | No (off-label use) |
J1572 |
Flebogamma DIF | Grifols | 5% / 10% liquid | Sorbitol | 500 mg | No (off-label use) |
J1556 |
Bivigam | ADMA Biologics | 10% liquid | Glycine | 500 mg | No (off-label use) |
J1557 |
Gammaplex | BPL / Bio Products Lab | 5% / 10% liquid | Glycine + sorbitol | 500 mg | No (off-label use) |
J1559 |
Hizentra (subcutaneous) | CSL Behring | 20% subcutaneous | L-proline | 100 mg | Yes (CIDP maintenance, SC) |
Brand-related billing patterns to avoid:
- Wrong code, right indication: billing J1561 (Gamunex-C / Gammaked) for a patient who actually received Gammagard Liquid (J1569) is a denial trigger and a compliance issue. ASP differences create a $/unit delta the payer will catch on audit.
- Right code, payer-mandated different brand: some payers contract preferentially with specific IVIG brands — UnitedHealthcare may steer to Privigen on one PA while Aetna may require Gammagard Liquid on the next, and several payers route CIDP to Gamunex-C / Gammaked specifically. Verify the payer's preferred brand on every PA; do not assume previous brand carries over.
- Mixing the dual-licensed pair: Gamunex-C and Gammaked share J1561, but the NDC labeler differs (13533 vs 76125). Match the NDC to the brand actually drawn.
When clinical brand justification is needed
- CIDP indication: Gamunex-C / Gammaked (J1561) and Privigen (J1459) are the IVIGs with FDA CIDP labeling; Hizentra (J1559) has CIDP labeling for SC maintenance. For an off-label IVIG choice in CIDP, payer-specific medical-necessity justification may be required.
- IgA deficiency: low-IgA IVIG products preferred to reduce anaphylaxis risk. Gamunex-C / Gammaked has low IgA content but is not the lowest in the class.
- Renal impairment / diabetes: sucrose-free, sorbitol-free, low-osmolality products preferred. Gamunex-C / Gammaked is glycine-stabilized (sucrose-free, sorbitol-free), making it a reasonable choice in renal-risk patients vs sorbitol-stabilized Flebogamma.
- Tolerability history: if a patient had infusion reactions on one brand, switching brands sometimes resolves them. Document the prior brand, the reaction, and the rationale.
- Subcutaneous transition: chronic PI patients who outgrow IV access may transition to SC IVIG — either Gamunex-C SC (still J1561) or a dedicated SC IG product (Hizentra J1559, Cuvitru, Cutaquig, Xembify, HyQvia). For a dedicated SC product, this is a brand and route switch — re-PA required.
Phase 2
Code the claim
IVIG is non-chemo (96365/96366), bills with JZ when no waste, JW for partial-vial waste. Site of care drives POS.
Administration codes CPT verified May 2026
IVIG is not chemotherapy. Use the therapeutic IV infusion family (96365 / 96366) for IV Gamunex-C, and the SC infusion family (96369 / 96370 / 96371) for SC Gamunex-C in PI. Expect to bill multiple add-on hours per IV dose because IVIG infusions run 2–6 hours.
| CPT | Description | Use for |
|---|---|---|
96365 |
Therapeutic / prophylactic / diagnostic IV infusion; up to 1 hour, single or initial substance | First hour of every IV Gamunex-C / Gammaked infusion (1 unit per date of service) |
96366 |
Therapeutic IV infusion; each additional hour | Hours 2–6 of IV Gamunex-C / Gammaked infusion (multiple units per date of service) |
96367 |
Therapeutic IV infusion; additional sequential infusion of new substance/drug, up to 1 hour | If a sequential drug (e.g., separately billed premed not given pre-infusion) is infused after Gamunex-C |
96374 |
Therapeutic IV push, single or initial substance/drug | IV push premedications (e.g., diphenhydramine IV, methylprednisolone IV bolus) |
96369 |
Subcutaneous infusion for therapy/prophylaxis; initial, up to 1 hour, including pump set-up | SC Gamunex-C in PI — first hour with pump |
96370 |
Subcutaneous infusion; each additional hour | SC Gamunex-C in PI — hours 2+ |
96371 |
Subcutaneous infusion; additional pump set-up with establishment of new subcutaneous infusion site | SC Gamunex-C in PI — multiple simultaneous infusion sites |
96413 / 96415 |
Chemotherapy IV infusion codes | Not appropriate for IVIG — Gamunex-C is non-chemotherapeutic. Using chemo codes is a coding error. |
S9338 |
Home infusion therapy, immunotherapy | Home infusion per-diem code (some commercial payers; Medicare uses different home infusion benefit codes) |
99601 / 99602 |
Home infusion / specialty drug administration, per visit (up to 2 hr) / each additional hour | Home-infusion provider administration codes (commercial payer use) |
Premedication coding
Standard Gamunex-C premedications are acetaminophen and diphenhydramine 30–60 minutes pre-infusion.
Some patients require IV corticosteroids (methylprednisolone, hydrocortisone). Premeds are billed
separately with the appropriate J-code (e.g., J1200 diphenhydramine, J1100
dexamethasone) and the appropriate admin code (96372 SC/IM, 96374 IV push, or
96365/96366 if infused). Oral acetaminophen is generally not separately billable.
Modifiers — JZ, JW, and the weight-based waste calculation CMS verified May 2026
All Gamunex-C / Gammaked vial sizes (1 g, 2.5 g, 5 g, 10 g, 20 g, 40 g) are single-dose containers. Weight-based dosing rarely matches an integer vial combination — partial-vial waste is the rule. The 1 g and 2.5 g vials help reduce waste at small body weights and pediatric doses.
JZ — required when no drug discarded
Effective July 1, 2023, CMS requires the JZ modifier on all single-dose container claims when no drug is discarded. For Gamunex-C / Gammaked, JZ applies when the dose happens to match an integer combination of the 1/2.5/5/10/20/40 g vials — e.g., a 35 g dose = 20 + 10 + 5 g = exactly three vials, no waste. Append JZ to the J1561 line.
JW — required for documented waste of unused single-dose-vial drug
For mg/kg dosing where the calculated dose does not match an integer vial combination, partial-vial waste is the norm. CMS requires the JW modifier on a separate claim line for the discarded units (rounded per CMS rules), with the wastage documented in the medical record. Bill administered units (with JZ) and discarded units (with JW) on two separate lines, same date of service.
Worked JW example — Gamunex-C, PI maintenance, 67.4 kg patient at 500 mg/kg:
Calculated dose: 500 mg/kg × 67.4 kg = 33,700 mg = 33.7 g
Vials drawn: 1 × 20 g + 1 × 10 g + 1 × 2.5 g + 1 × 1 g = 33.5 g (smallest combination ≥ 33.7 g would be 20 + 10 + 2.5 + 1 + 1 = 34.5 g)
Vials drawn (revised): 1 × 20 g + 1 × 10 g + 2 × 2.5 g = 35 g total
Administered: 33,700 mg
Discarded: 35,000 − 33,700 = 1,300 mg
Convert to units (1 unit = 500 mg):
Administered units: 33,700 / 500 = 67.4 → round per CMS / MAC rule
Discarded units: 1,300 / 500 = 2.6 → round per CMS / MAC rule
Claim lines (illustrative; apply local MAC rounding):
Line 1: J1561 · JZ · ~67 units (administered)
Line 2: J1561 · JW · ~3 units (discarded)
Apply each MAC's rounding convention. Some MACs require billing the total drawn from the vial as administered units and reporting waste only when an entire additional vial would otherwise be required. Refer to your local MAC billing article for the exact rounding rule. The Gamunex-C / Gammaked 1 g and 2.5 g vials reduce waste at borderline doses vs IVIG products that start at 5 g (e.g., Privigen) — a small clinical-and-billing advantage for pediatric and small-adult patients.
JG / TB — 340B drug pricing
Hospitals that purchase Gamunex-C / Gammaked through 340B and bill Medicare report the JG modifier (acute-care hospitals) or TB modifier (rural sole community / critical-access hospitals), per CMS guidance. Most ambulatory infusion suites and home infusion providers do not use 340B pricing; only hospital-outpatient infusion uses 340B in most networks.
Modifier 25 — same-day E/M
Append modifier 25 to the same-day E/M code if a significant, separately identifiable evaluation occurred (clinical reassessment for next-cycle decision, dose-titration encounter, INCAT scoring for CIDP, etc.). Routine pre-infusion check-in is bundled.
ICD-10-CM diagnosis codes FY2026 verified May 2026
Use the most specific code supported by chart documentation. Each FDA-approved indication has a distinct code family; payer LCDs may add additional covered codes.
| Indication | ICD-10 family | Examples |
|---|---|---|
| Primary humoral immunodeficiency — antibody-predominant | D80.x |
D80.0 (hereditary hypogammaglobulinemia); D80.1 (non-familial hypogammaglobulinemia); D80.3 (selective IgG subclass deficiency); D80.4 (selective IgM); D80.5 (immunodeficiency w/ ↑ IgM); D80.6 (antibody deficiency w/ near-normal Ig levels); D80.9 (immunodeficiency w/ predominantly antibody defects, unspecified) |
| Primary immunodeficiency — combined | D81.x |
D81.0 (SCID, reticular dysgenesis); D81.1 (SCID w/ low T & B cells); D81.2 (SCID w/ low/normal B); D81.6 (MHC class I); D81.7 (MHC class II); D81.89 (other combined ID); D81.9 (combined ID, unspec) |
| Other immunodeficiencies | D82.x |
D82.0 (Wiskott-Aldrich); D82.1 (DiGeorge); D82.3 (immunodeficiency following hereditary defective response to EBV); D82.4 (hyper-IgE); D82.8 (other specified ID with major defects); D82.9 (ID w/ major defects, unspec) |
| Common variable immunodeficiency (CVID) | D83.x |
D83.0 (CVID w/ predominant abnormalities of B-cell numbers/function); D83.1 (CVID w/ predominant immunoregulatory T-cell disorders); D83.2 (CVID w/ autoantibodies to B or T cells); D83.8 (other CVID); D83.9 (CVID, unspecified) |
| Chronic immune thrombocytopenic purpura (ITP) | D69.3 |
D69.3 (immune thrombocytopenic purpura) |
| CIDP (Gamunex-C signature indication) | G61.81 |
G61.81 (chronic inflammatory demyelinating polyneuritis / CIDP) — Gamunex-C / Gammaked carries the original 2008 FDA CIDP indication and is one of the IVIGs most commonly preferred by payers for this code |
Pair the diagnosis with the right indication. Gamunex-C / Gammaked is FDA-approved only for
PI, ITP, and CIDP. Off-label IVIG use (myasthenia gravis, Guillain-Barré, Kawasaki disease,
dermatomyositis, multifocal motor neuropathy, etc.) requires payer-specific coverage verification —
many payers cover off-label IVIG only for selected indications and require step therapy or compendium support.
Site of care & place of service Verified May 2026
IVIG site-of-care steerage is among the most aggressive in specialty pharmacy. Home infusion is preferred for chronic PI and CIDP at most national payers; HOPD claims are routinely denied or downcoded.
| Setting | POS | Claim form | Electronic | Payer preference |
|---|---|---|---|---|
| Home infusion (POS 12) | 12 | CMS-1500 | 837P | Preferred for chronic PI & CIDP at UHC, Aetna, Cigna, most BCBS. Specialty home-infusion vendor (Coram, Option Care, Amerita, Optum Infusion, etc.) typically required. |
| Patient self-administration at home (SC, POS 12) | 12 | CMS-1500 | 837P | Preferred for stable chronic PI on Gamunex-C SC — after training, patient self-administers weekly with pump. |
| Ambulatory infusion center / suite (POS 49) | 49 | CMS-1500 | 837P | Preferred when home infusion not feasible (first dose, observed reactions, vascular access issues). Lower facility cost than HOPD. |
| Physician office (POS 11) | 11 | CMS-1500 | 837P | Acceptable; less common for high-dose IVIG due to chair-time (2–6 hr per dose). May be used for low-dose PI maintenance or SC PI dosing. |
| On-campus hospital outpatient (POS 22) | 22 | UB-04 / CMS-1450 | 837I | Disfavored. First infusions, high-risk patients, or post-reaction patients only. Payers actively redirect to AIC or home after stable. |
| On-campus hospital outpatient (POS 19, alt) | 19 | UB-04 / CMS-1450 | 837I | Disfavored. Same as POS 22. |
| Off-campus hospital outpatient (POS 19) | 19 | UB-04 / CMS-1450 | 837I | Disfavored. Site-neutral payment rules + payer steerage both work against HOPD. |
Home infusion vs. ambulatory infusion vs. hospital outpatient — the three-way decision
- Home infusion (POS 12) — Lowest total cost. Patient receives infusion at home via a contracted home-infusion provider. Drug + nursing + supplies bundled per the home-infusion benefit (commercial: per-diem codes like S9338; Medicare Part B home infusion benefit covers select drugs). Best for stable, tolerant chronic patients with adequate venous access. UHC Optum Infusion steerage is particularly aggressive for chronic IVIG. SC Gamunex-C is naturally home-friendly and is often the destination route for stable chronic PI patients.
- Ambulatory infusion center (POS 49) — Mid-range cost. Free-standing AIC or physician-office-affiliated infusion suite. Lower facility fees than HOPD. Standard for chronic patients who are not home-infusion candidates and for new-start patients in observation period.
- Hospital outpatient (POS 19/22) — Highest total cost. OPPS / APC packaging adds substantial facility fees on top of drug ASP. Payers actively steer away from HOPD for IVIG after the first 1–3 doses. New IVIG starts where reaction risk is uncertain may be HOPD-justified; chronic stable IVIG should not be.
Site-of-care attestation is often part of IVIG PA. UnitedHealthcare and Aetna require
the prescriber to attest that the patient cannot reasonably receive infusion at home or in an AIC before
approving HOPD. Submitting an HOPD claim without the attestation will deny. Build site-of-care planning
into the initial PA submission, not as an afterthought.
Claim form field mapping Grifols / Kedrion billing guides + CMS-1500 reference
CMS-1500 / 837P (physician office, AIC, home infusion; POS 11/12/49) example for a 35 g PI maintenance dose of Gamunex-C.
| Information | CMS-1500 box | Notes |
|---|---|---|
| NDC qualifier + 11-digit NDC + UoM + qty | 24A shaded area | Format: N4 + Grifols 13533... or Kedrion 76125... NDC + ML + total volume; one line per NDC drawn |
| HCPCS J1561 + JZ | 24D (drug line) | 35 g = 70 units; JZ when no waste (matched-vial dose) |
| HCPCS J1561 + JW (when waste) | 24D (separate line) | Discarded units (per weight-based dose calculation) |
| Drug units | 24G | 70 (for 35 g PI dose); split administered + waste if JW |
| CPT 96365 + 96366 (IV) | 24D (admin lines) | 1 unit 96365 + N units 96366 for hours 2+ (typically 1–5 add-on hours) |
| CPT 96369 + 96370 + 96371 (SC) | 24D (admin lines) | For SC Gamunex-C in PI — SC infusion family with pump set-up codes |
| ICD-10 | 21 | Indication-specific (D80.x, D83.x, D69.3, G61.81, etc.) |
| Dates of service | 24A | Same date for drug + admin lines; multi-day CIDP loading bills each day separately |
| NPI | 17b / 24J / 33a | Rendering and billing provider NPI |
| PA number | 23 | Required by UHC, Aetna, Cigna, most BCBS for all IVIG starts and reauthorizations |
| Site-of-care attestation | Attached | Required at PA stage for HOPD billing; commonly required for chronic IVIG |
| JG / TB modifier (340B sites only) | 24D | Hospital outpatient 340B claims only |
Source: Grifols Gamunex-C billing & coding guide; Kedrion Gammaked billing reference; CMS-1500
instruction manual; payer policy documents (UHC, Aetna, Cigna, Anthem). Home infusion claims may use
additional per-diem codes (S9338 commercial, Medicare Part B home infusion benefit codes).
Phase 3
Get paid
IVIG PA is universal. Site-of-care steerage is the dominant 2026 UM lever. CIDP-specific brand mandates often favor Gamunex-C / Gammaked.
Payer policy snapshot — LCD & PA criteria Reviewed May 2026
Every major payer requires PA on every IVIG start and at every reauthorization. Site-of-care UM is universal. Brand mandates vary by payer contract and refresh annually; for CIDP specifically, Gamunex-C / Gammaked is frequently the preferred brand given the FDA CIDP indication.
| Payer | PA? | Brand preference | Site-of-care steering | Reauth interval |
|---|---|---|---|---|
| UnitedHealthcare commercial UHC IVIG medical drug policy + Optum Infusion + MCG criteria |
Yes (every start; every reauth) | Brand rotates by contract; for CIDP, Gamunex-C / Gammaked often preferred for the FDA CIDP indication | Aggressive. Optum Infusion home steerage for chronic PI/CIDP; AIC for new starts; HOPD requires attestation. | 6–12 months |
| Aetna commercial CPB 0206 / IVIG MCG criteria |
Yes | Multiple preferred brands; Gamunex-C / Gammaked frequently preferred for CIDP; Privigen and Gammagard Liquid commonly preferred for PI | Aggressive home/AIC steerage; HOPD requires medical-necessity justification | 6–12 months |
| Cigna commercial IP0011 IVIG coverage policy |
Yes | Multiple preferred brands; Gamunex-C / Gammaked typically covered without specific brand mandate; preferred for FDA CIDP indication | Aggressive AIC / Accredo home infusion steerage | 6–12 months |
| BCBS (most plans) Plan-by-plan; Carelon for many |
Yes | Plan-specific; verify per state plan; CIDP often favors Gamunex-C / Gammaked or Privigen | Aggressive; CareSite / specialty home infusion preferred | 6–12 months |
| Medicare Part B (MAC LCDs) Multiple MAC LCDs; covered ICD-10 lists |
Coverage by LCD (no PA on FFS); MA plans require PA | No brand preference (FFS); MA plans may steer | Site of care follows POS rules; home infusion benefit applies for select drugs | n/a (FFS); 6–12 mo (MA) |
What to document for IVIG PA approval
- For PI: documented serum IgG levels (low for age); functional antibody response to vaccine challenge OR pre-existing antibody titers below protective; recurrent infection history with objective documentation (cultures, imaging, hospitalizations).
- For CIDP: neurologist documentation of clinical course (progressive or relapsing weakness >2 months); EMG/NCS findings consistent with demyelination; exclusion of other causes; baseline INCAT or MRC sum score. Naming Gamunex-C / Gammaked specifically (citing the FDA CIDP label) often streamlines approval.
- For ITP: platelet count (typically <30,000/µL for treatment) AND bleeding history or significant bleeding risk; failure or contraindication to corticosteroid therapy (per most payer criteria for chronic ITP).
- Site-of-care attestation: patient suitability for home infusion (vascular access, caregiver availability, prior tolerance) OR justification for AIC / HOPD (first dose, prior reaction history, complex medical needs). For chronic PI patients, document SC eligibility if applicable.
- Reauthorization: documented continued benefit (IgG trough levels for PI; INCAT/MRC score improvement or stability for CIDP; platelet response for ITP).
Brand mandates rotate annually. Payer-preferred IVIG brands shift with contracting
cycles. A patient stable on Gamunex-C in 2025 may be required to switch to Gammaked (no clinical change)
or to a different IVIG entirely in 2026 if the payer's preferred brand changes. Build brand-verification
into every reauthorization workflow; do not assume brand continuity.
Medicare reimbursement CMS Q2 2026 (live)
Quarterly ASP from CMS Part B Drug Pricing File. J1561 refreshes every quarter; the per-500-mg-unit rate translates to a per-gram cost via × 2.
Q2 2026 payment snapshot — J1561 Gamunex-C / Gammaked
Effective April 1 – June 30, 2026 · Based on 4Q25 ASP submissions
ASP + 6%
$49.726
per 500 mg unit (= ~$99.45 per gram)
35 g PI maintenance dose
$3,480.82
70 units × ASP+6%
100 g CIDP induction
$9,945.20
200 units × ASP+6%
Per-dose Medicare reimbursement at common Gamunex-C / Gammaked doses
| Dose (g) | Units | ASP+6% allowed | After ~2% sequestration |
|---|---|---|---|
| 1 g | 2 | $99.45 | ~$97 |
| 5 g | 10 | $497.26 | ~$487 |
| 10 g | 20 | $994.52 | ~$975 |
| 20 g | 40 | $1,989.04 | ~$1,949 |
| 35 g (typical PI) | 70 | $3,480.82 | ~$3,411 |
| 50 g | 100 | $4,972.60 | ~$4,873 |
| 70 g (1 g/kg, 70 kg CIDP) | 140 | $6,961.64 | ~$6,822 |
| 100 g | 200 | $9,945.20 | ~$9,746 |
| 140 g (2 g/kg, 70 kg CIDP load) | 280 | $13,923.28 | ~$13,645 |
Coverage
No NCD specific to IVIG as a class. Each MAC publishes a billing & coding article covering IVIG with covered ICD-10 ranges per indication. Medicare covers Gamunex-C / Gammaked for FDA-approved indications (PI, ITP, CIDP). Off-label IVIG indications (myasthenia gravis, Guillain-Barré, dermatomyositis, multifocal motor neuropathy, etc.) are covered on a MAC-by-MAC basis — verify the local LCD before billing. Bill with the indication-specific ICD-10 (see ICD-10 by indication).
Canonical code source: CMS HCPCS quarterly update file.
Patient assistance — Grifols PathConnect (Gamunex-C) + Kedrion KedPlasma (Gammaked) Manufacturer sites verified May 2026
Gamunex-C — Grifols PathConnect
- Phone: 1-855-477-2672 — Grifols PathConnect / Gamunex-C patient support hub
- Gamunex-C Co-pay Assistance Program (commercially-insured): Eligible commercially-insured patients may qualify for copay support, with annual benefit caps that vary by patient and program year. Verify current cap with PathConnect at PA stage.
- Grifols Patient Assistance Program (uninsured / underinsured): Free Gamunex-C for qualifying uninsured patients and for underinsured patients whose insurance does not cover IVIG. Income-based eligibility.
- Reimbursement support: PathConnect offers benefit verification, PA support, appeal letters, and product replacement for spoiled / damaged vials.
Gammaked — Kedrion KedPlasma Patient Assistance
- Kedrion KedPlasma Patient Assistance Program: Patient support for Gammaked, including benefit investigation, copay support for commercially-insured patients, and patient assistance for uninsured / underinsured patients meeting income criteria. Contact KedPlasma directly for current program terms and contact details.
Independent foundations (Medicare patients)
- PAN Foundation, HealthWell Foundation, Patient Advocate Foundation, and the Assistance Fund all run open-disease IVIG funds intermittently. Verify open funds quarterly — IVIG funds are high-demand and frequently close.
- For CIDP specifically, neuropathy-focused funds (e.g., GBS|CIDP Foundation International) may have patient-assistance programs in addition to the open-disease IVIG funds.
Need to model what a specific patient will actually pay after copay assistance, deductible, coinsurance,
and OOP max? Run a CareCost Estimate — J1561 (Gamunex-C / Gammaked)
and the IVIG siblings (J1459 Privigen, J1569 Gammagard Liquid, J1568 Octagam, J1559 Hizentra SC)
pre-loaded.
Phase 4
Fix problems
Top three IVIG denial themes: unit-basis errors (500 mg/unit), site-of-care steerage, brand mismatch (including the dual-licensed labeler trap).
Common denials & how to fix them
| Denial reason | Common cause | Fix |
|---|---|---|
| Wrong unit count (500x over- or 2x under-bill) | Biller defaulted to 1 mg/unit (most J-codes) or 1 g/unit (IVIG mental shortcut) instead of 500 mg/unit | Recalculate: mg ÷ 500 = units, OR g × 2 = units. 35 g = 70 units, not 35 and not 35,000. |
| Wrong J-code (J1561 instead of correct IVIG brand) | Gamunex-C / Gammaked billed when patient received Privigen, Gammagard Liquid, Octagam, etc. | Verify the brand actually infused. Match HCPCS to NDC drawn: J1561 = Grifols labeler 13533 OR Kedrion labeler 76125; J1459 = Privigen (CSL 44206); J1569 = Gammagard Liquid (Takeda); J1568 = Octagam (Octapharma). |
| NDC labeler mismatch (Grifols vs Kedrion within J1561) | Gamunex-C drawn but Gammaked NDC reported (or vice versa) — both bill J1561 but the NDC labeler must match | Use NDC matching the brand drawn: Grifols 13533-... for Gamunex-C, Kedrion 76125-... for Gammaked. The J-code stays the same. |
| Site-of-care denial (HOPD) | Chronic IVIG billed POS 19/22 when payer requires home or AIC | Move to home infusion (POS 12) or AIC (POS 49). For HOPD, submit medical-necessity attestation (first dose, prior reaction, vascular access, etc.). Consider SC Gamunex-C for stable PI patients. |
| PA missing or expired | IVIG infused without active PA (every start; every reauth) | Submit retro-PA where allowed; rebill with PA number in Box 23. |
| Brand-mandate violation | Patient infused with non-preferred brand for the payer; or for CIDP, an off-label IVIG used when the payer prefers FDA-labeled Gamunex-C / Privigen | Request brand override (medical necessity); for next cycle, switch to payer's preferred brand and update PA. For CIDP, cite the FDA CIDP label for J1561 / J1459. |
| JZ missing | Single-dose-vial claim without JZ when no drug was discarded | Resubmit with JZ on the J1561 line (matched-vial doses). |
| JW missing on weight-based dose | mg/kg dose with vial waste not reported | Add separate line with JW for discarded units (per CMS rounding); document waste in chart. |
| NDC format / qualifier missing | 10-digit NDC submitted; missing N4 qualifier or unit-of-measure | Use 11-digit NDC with N4 qualifier in CMS-1500 Box 24A shaded area; report ML and quantity drawn from each vial. |
| Insufficient PI documentation | IgG trough not documented; functional antibody response missing; recurrent infection history not in chart | Submit IgG trough lab; add vaccine-challenge response or pre-existing antibody titers; document infections with cultures/imaging. |
| CIDP without EMG/NCS | CIDP indication billed without electrodiagnostic confirmation | Attach neurologist note + EMG/NCS report consistent with demyelination; INCAT/MRC scoring helpful. Cite Gamunex-C FDA CIDP label as evidence-based first-line. |
| ITP without bleeding documentation | Chronic ITP indication with platelet count alone (no bleeding history or risk) | Add bleeding-risk assessment; document failure or contraindication to corticosteroid therapy. |
| Chemo admin codes (96413/96415) used | IVIG miscoded as chemotherapy | Resubmit with 96365 + 96366 (IV) or 96369/96370/96371 (SC). IVIG is non-chemo; chemo admin codes are an automatic edit. |
| Wrong admin family for SC route | SC Gamunex-C billed with IV admin codes (96365/96366) instead of SC infusion family | Use 96369 (SC initial up to 1 hr with pump), 96370 (each additional hr), 96371 (additional pump set-up). |
| Off-label indication not covered | IVIG billed for an off-label use without LCD support | Verify payer's covered ICD-10 list / compendium support; submit medical-necessity letter; consider switching to a covered indication if mis-documented. |
Frequently asked questions
How many units do I bill for a Gamunex-C / Gammaked dose?
Gamunex-C and Gammaked both bill under HCPCS J1561 at 1 unit = 500 mg. This
is unusual — most J-codes use 1 mg per unit, and many IVIG-aware billers default to 1 g per unit.
For J1561 specifically: a 35 g dose = 70 units (35,000 mg ÷ 500); a 70 g dose = 140 units; a 140 g
loading dose for CIDP = 280 units. Defaulting to 1 mg/unit will overbill by 500x; defaulting to 1 g/unit
will underbill by 2x. Both errors are major audit risks. Conversion shortcut:
grams × 2 = units.
Why are Gamunex-C and Gammaked the same product?
Gamunex-C (Grifols) and Gammaked (Kedrion) are dual-licensed under the same biologics license — the
identical molecule, manufactured at the same facility, sold under two brand names by two manufacturers.
HCPCS J1561 explicitly covers both ("Inj, immune globulin (gamunex-c/gammaked) non-lyophilized,
500 mg"). NDCs differ by labeler (Grifols 13533 vs Kedrion 76125), but the
product is interchangeable for clinical purposes. Payers may contract preferentially with one brand over
the other, but the same J-code is used to bill either.
What is the Q2 2026 Medicare reimbursement for J1561?
Q2 2026 ASP + 6% for J1561 is approximately $49.726 per 500 mg unit, which is approximately $99.45 per gram. A typical 35 g monthly PI maintenance dose = 70 units × $49.726 = $3,480.82 before sequestration. A 100 g CIDP induction = 200 units = $9,945.20. ASP refreshes quarterly — see the live snapshot above.
What are the FDA-approved indications for Gamunex-C / Gammaked?
Three FDA-approved indications: (1) primary humoral immunodeficiency (PI) in adults and children ≥2 years, dosed 300–600 mg/kg IV every 3–4 weeks (or 100–200 mg/kg/week SC) targeting an IgG trough of 500–1,000 mg/dL; (2) chronic ITP in adults and children ≥3 years, dosed 1 g/kg/day for 1–2 days as induction; (3) CIDP in adults — Gamunex-C was the first FDA-approved IVIG for CIDP (2008) and remains the IVIG with the strongest CIDP evidence base. CIDP loading is 2 g/kg over 2–4 days followed by 1 g/kg every 3 weeks.
Does Gamunex-C have a subcutaneous route?
Yes. Gamunex-C is one of the few IVIG products also approved for subcutaneous (SC) administration in
primary immunodeficiency patients. The PI SC dose is 100–200 mg/kg per week, calculated to deliver
the same monthly dose as the IV regimen (typically the IV dose × 1.37 conversion factor split across
weekly SC doses). Despite being the same product, IV and SC administration have different billing pathways:
J1561 is the HCPCS code for both routes (1 unit = 500 mg). For SC administration use
96369 / 96370 / 96371 SC infusion codes; for IV use
96365 / 96366. Verify SC coverage with the payer — some payers track SC
IVIG use under broader subcutaneous immune globulin coverage policies.
Why is Gamunex-C often the preferred IVIG for CIDP?
Gamunex-C was the first FDA-approved IVIG specifically for CIDP (approved September 2008 based on the ICE trial). It has the deepest CIDP evidence base in the IVIG class and is the IVIG most explicitly cited in AAN/EAN/PNS CIDP guidelines as a treatment option. Many payers' CIDP coverage policies name Gamunex-C / Gammaked as a preferred or required IVIG specifically for the CIDP indication (sometimes alongside Privigen J1459, which received CIDP approval in 2017). For PI and ITP, payer brand preference varies; for CIDP specifically, Gamunex-C / Gammaked's evidence base often gets it preferred status.
Why does the JW modifier apply to IVIG even though Gamunex-C comes in single-dose vials?
All IVIG dosing is weight-based (mg/kg), so the calculated dose almost never matches an integer combination of the 1 g, 2.5 g, 5 g, 10 g, 20 g, and 40 g vial sizes. Vial-level waste is routine. CMS requires JZ on the administered units when no waste occurs, and JW on a separate line for the discarded units when an SDV is partially used. Document waste in the medical record. Small mg/kg variations on a high-cost drug like IVIG translate to thousands of dollars of waste per dose — payers audit JW closely. The Gamunex-C 1 g and 2.5 g vials reduce waste vs IVIG products that start at 5 g.
Are IVIG brands interchangeable for billing purposes?
No — with the exception of the dual-licensed Gamunex-C and Gammaked, which share J1561.
Each other IVIG product has its own HCPCS code, NDC, and ASP (Privigen J1459, Gammagard Liquid
J1569, Octagam J1568, Bivigam J1556, Gammaplex J1557,
Flebogamma J1572, etc.). Substituting brands without matching the HCPCS to the actual product
administered is a denial trigger and a compliance issue. Many payers contract preferentially with specific
brands — for CIDP especially, many policies prefer Gamunex-C / Gammaked for its FDA-approved CIDP
indication and historical evidence base.
What administration codes are used for Gamunex-C / Gammaked?
IVIG is non-chemotherapeutic. For IV administration use 96365 (therapeutic IV infusion,
initial hour) plus 96366 (each additional hour) — IV infusions typically run 2–6
hours per dose because the rate is titrated up gradually from 1 mg/kg/min, so multiple 96366
units are billed per session. For SC Gamunex-C in PI use 96369 / 96370 /
96371. Do not use the chemo admin codes 96413/96415 for IVIG.
Premedications (acetaminophen, diphenhydramine, occasionally IV corticosteroids) are billed separately
with their own J-codes and admin codes.
Who manufactures Gamunex-C and Gammaked, and what is the patient assistance contact?
Gamunex-C is manufactured by Grifols Therapeutics (the originator brand). Gammaked is the dual-licensed brand sold by Kedrion Biopharma. Patient support for Gamunex-C runs through Grifols PathConnect at 1-855-477-2672 — benefit verification, prior authorization assistance, copay support for commercially-insured patients, and free product through the Grifols Patient Assistance Program for uninsured/underinsured patients meeting income requirements. Gammaked support runs through Kedrion KedPlasma Patient Assistance. For Medicare patients, refer to PAN, HealthWell, and the Assistance Fund — verify open IVIG funds quarterly.
Reference
Sources & methodology
Every claim on this page is sourced. Methodology and review history below.
Source documents
- AAPC — HCPCS J1561 (Gamunex-C / Gammaked)
- Gamunex-C HCP resources (Grifols)
- FDA-approved Gamunex-C prescribing information
- Gammaked HCP resources (Kedrion Biopharma)
- ICE trial — Hughes et al., Lancet Neurology 2008
- AAAAI — Primary Immunodeficiency Practice Parameters
- AAN / EAN/PNS — CIDP guidelines
- ASH 2019 ITP guidelines
- UnitedHealthcare — Immune Globulin medical drug policy
- Aetna CPB 0206 — Intravenous Immune Globulin
- Cigna IP0011 — Immune Globulin IV coverage policy
- CMS — Medicare Part B Drug ASP Pricing File
- CMS — HCPCS quarterly update file
- CMS — JW / JZ modifier guidance
- CMS — Medicare home infusion therapy benefit
- Immune Deficiency Foundation (IDF)
- GBS|CIDP Foundation International
About this page
We maintain this page as a living reference for Gamunex-C / Gammaked (J1561) and the broader IVIG class. Medicare ASP pricing for J1561 (and the IVIG sibling codes) is bound to our underlying CareCost data layer and refreshes automatically when CMS publishes new quarterly files. Coding and policy content is reviewed at least quarterly and updated whenever a manufacturer guide, FDA label, or major payer policy changes.
Found an error? Email hello@carecostestimate.com.
Refresh cadence
| Element | Cadence | How it's refreshed |
|---|---|---|
| Medicare ASP pricing (J1561) | Quarterly | Auto-bound to CareCost ASP layer; updates on CMS file release. |
| Payer policies (UHC, Aetna, Cigna, BCBS) | Semi-annual | Manual review against published payer IVIG policy documents; brand-preference (incl. CIDP-specific Gamunex-C / Gammaked preference) and site-of-care criteria re-checked annually. |
| HCPCS / CPT / NCCI rules | Annual | Reviewed against CMS HCPCS quarterly files, AMA CPT releases, and NCCI edit updates. |
| NDC, dosing, FDA label, infusion rate titration, IV vs SC | Event-driven | Tied to Grifols / Kedrion document version + FDA Gamunex-C label revision date. |
Reviewer
Pending SME review. This page is staff-authored from primary sources (FDA Gamunex-C label,
CMS HCPCS / ASP files, Grifols PathConnect billing & coding guide, Kedrion Gammaked reference,
AAAAI / AAN / ASH guidelines, ICE trial publication, and payer IVIG policies — all linked above).
Editorial review in progress. Until that review is complete, treat this
as a draft reference and verify each cited source for high-stakes claims. NDC examples are illustrative;
confirm current package configurations against the FDA NDC Directory at billing time.
Change log
- — Initial publication of the Gamunex-C / Gammaked (J1561) reference. ASP data: Q2 2026. Dual-licensing (Grifols + Kedrion) documented. CIDP signature indication (first FDA-approved IVIG for CIDP, 2008, ICE trial) emphasized. IV + SC route coverage explained. Payer policies verified: UnitedHealthcare immune globulin medical drug policy, Aetna CPB 0206, Cigna IP0011 IVIG, BCBS plan-by-plan. Grifols PathConnect (1-855-477-2672) and Kedrion KedPlasma patient assistance contacts verified. Site-of-care steerage documented.
Methodology
Every claim on this page is sourced inline. Pricing reflects the current CMS Part B Drug ASP Pricing File for J1561. Payer policies are read directly from each payer's published medical policy documents. We do not paraphrase from billing-software vendor blogs. The CIDP-specific brand-preference framing reflects the clinical reality that Gamunex-C / Gammaked carries the original (2008) FDA CIDP indication and the deepest CIDP RCT evidence (ICE trial) — this routinely shapes payer coverage decisions even where formal brand mandates are not in writing.