HCPCS
J1558
100 mg = 1 unit (NOT 500 mg)
Phase 1
Identify what you're billing
SCIG vs IVIG is the first decision; everything downstream changes from there.
SCIG (Xembify) vs. IVIG — the foundational billing distinction FDA + payer verified May 2026
Same therapeutic class (immune globulin), different molecules in the bottle, very different billing infrastructure.
Immune globulin therapy splits into two delivery routes: intravenous (IVIG — Privigen, Gammagard Liquid, Octagam, Gamunex-C, etc.) and subcutaneous (SCIG — Xembify, Hizentra, Cuvitru, Cutaquig, plus Gamunex-C which is IV+SC dual-approved). They are clinically interchangeable for stable patients with primary humoral immunodeficiency, but the billing infrastructure differs from the unit basis on up.
| Xembify (SCIG) | IVIG (Privigen / Gammagard Liquid / Octagam / Gamunex-C) | |
|---|---|---|
| HCPCS | J1558 | J1459 Privigen, J1569 Gammagard Liquid, J1568 Octagam, J1561 Gamunex-C |
| Unit basis | 100 mg = 1 unit | 500 mg = 1 unit |
| Concentration | 20% (200 mg/mL) | 5% or 10% (50 or 100 mg/mL) |
| Route | Subcutaneous, mechanical pump | Intravenous, gravity or pump |
| Admin CPT | 96369 + 96370 + 96371 | 96365 + 96366 |
| Typical session length | 60–120 minutes | 2–4 hours (rate titration required) |
| Frequency | Weekly (or biweekly) | Every 3–4 weeks |
| Dominant site | Patient home (POS 12) after training | Ambulatory infusion (POS 49) or hospital outpatient (POS 19/22) |
| IgG kinetics | Flat trough (steady-state) | Peaks & troughs (post-infusion peak, pre-next-infusion trough) |
| Side-effect profile | Local site reactions; very rare systemic | Headache, fever, chills (rate-related); rare TRALI / aseptic meningitis / thrombosis |
| Clinical advantages | Lifestyle flexibility, lower systemic AEs, home-friendly | Faster IgG correction, less frequent admin, better for unstable / loading dose |
| Payer steerage (UHC, several BCBS) | Often preferred for stable PI | Often required to step through SCIG trial first (chronic stable patients) |
Major payer trend (2024–2026): UnitedHealthcare, Aetna, and several BCBS plans have
added SCIG-preference language to their immune globulin LCDs. For chronic stable PI, the
plan may require a documented SCIG trial (or contraindication) before approving ongoing IVIG. This makes
SCIG conversion a routine clinical event — bill the IVIG-to-SCIG transition cleanly (see
conversion math).
SCIG-preference does not mean cheaper per gram. Xembify's per-gram ASP runs higher than
most IVIG products (20% concentration premium + delivery convenience). The payer's interest is in
eliminating chair time + reducing systemic AE costs — not drug acquisition cost. See
Medicare reimbursement for per-gram comparisons. Within the SCIG class,
however, Xembify is positioned as the lowest-cost 20% option vs Cuvitru and competes closely with Hizentra.
Dosing & unit math FDA label verified May 2026
From the FDA Xembify prescribing information (BLA 125687).
Primary humoral immunodeficiency (PI) — adults & children ≥2 yr
- Conversion from IVIG: initial weekly Xembify dose = (previous monthly IVIG dose × 1.37) ÷ 4. Initiate ~1 week after the last IVIG dose.
- Maintenance range: typically 100–200 mg/kg per week SC, adjusted to maintain therapeutic IgG trough.
- Frequency options: weekly (most common) or biweekly (2× weekly dose every 2 weeks).
- Pediatric: approved for ages 2 years and older with PI — same mg/kg/week framework.
Indication scope — PI only
Xembify is FDA-approved for PI only. Unlike Hizentra (which carries an FDA-approved CIDP maintenance indication added in 2018), Xembify does not have a CIDP indication on label as of 2026. For CIDP maintenance therapy, route to Hizentra (J1559), HyQvia (J1575, 2024 CIDP approval), or an IVIG product. Off-label CIDP use of Xembify will be denied by most major payers.
Worked example — PI patient on 10 g/week (typical adult ~70 kg, 140 mg/kg)
# Per-infusion (weekly)
Drug mg per dose: 10,000 mg (10 g)
Drug units billed (J1558): 100 # 10,000 ÷ 100 mg/unit
HCPCS: J1558 · Modifier: JZ
Vials: 1 × 10 g/50 mL single-dose vial (or 2 × 5 g, or 2 × 4 g + 1 × 2 g, etc.)
Admin: 96369 (initial 1 hr, pump set-up + first SC site)
+ 96370 (each additional hour, if infusion runs >60 min)
+ 96371 (additional pump set-up + new SC site, if 2 sites used)
# Year-1 totals (52 weekly infusions)
Total drug units billed: 5,200 (52 × 100)
Total drug cost (Q2 2026 ASP+6%): ~$79,908 before sequestration
Drug mg per dose: 10,000 mg (10 g)
Drug units billed (J1558): 100 # 10,000 ÷ 100 mg/unit
HCPCS: J1558 · Modifier: JZ
Vials: 1 × 10 g/50 mL single-dose vial (or 2 × 5 g, or 2 × 4 g + 1 × 2 g, etc.)
Admin: 96369 (initial 1 hr, pump set-up + first SC site)
+ 96370 (each additional hour, if infusion runs >60 min)
+ 96371 (additional pump set-up + new SC site, if 2 sites used)
# Year-1 totals (52 weekly infusions)
Total drug units billed: 5,200 (52 × 100)
Total drug cost (Q2 2026 ASP+6%): ~$79,908 before sequestration
Vial size to dose mapping
| Patient size / weekly dose | Vial combination (1 of many) | Total mg | Units billed |
|---|---|---|---|
| ~50 kg / 5 g weekly | 1 × 5 g (no waste) | 5,000 mg | 50 units |
| ~70 kg / 7 g weekly | 1 × 5 g + 1 × 2 g | 7,000 mg | 70 units |
| ~70 kg / 8 g weekly | 2 × 4 g | 8,000 mg | 80 units |
| ~70 kg / 10 g weekly | 1 × 10 g | 10,000 mg | 100 units |
| ~85 kg / 12 g weekly | 1 × 10 g + 1 × 2 g | 12,000 mg | 120 units |
| Large patient / 20 g weekly | 1 × 20 g | 20,000 mg | 200 units |
Xembify's vial size advantage: Xembify is the only 20% SCIG offering both a 5 g and 20 g
vial in the United States. The 5 g size enables clean fills for ~50–70 kg patients on weekly dosing
without combining multiple smaller vials, and the 20 g size minimizes waste for high-dose patients. For
billers, this often translates to fewer JW (waste) lines than equivalent Hizentra or Cuvitru claims.
Round to vial size; bill mg actually drawn. Xembify's 200 mg/mL concentration means
small mg differences map to small mL differences. Choose the vial combination that minimizes waste; bill
the mg administered, not the mg ordered. Use JW for any discarded portion of a single-dose vial.
IVIG → SCIG conversion (the 1.37 factor) FDA label verified May 2026
The single most-asked question when transitioning a stable PI patient from IVIG to Xembify.
SCIG bioavailability and trough kinetics differ from IV. The Xembify label specifies a conversion coefficient of 1.37 applied to the prior monthly IVIG dose, then divided across the weekly SCIG schedule (the same factor used by Hizentra and Cuvitru — the 1.37 is class-wide for 20% SCIG):
# Xembify weekly dose calculation
Weekly Xembify dose (g) = (Previous monthly IVIG dose (g) × 1.37) ÷ 4
# Examples
20 g monthly IVIG → (20 × 1.37) ÷ 4 = 6.85 g weekly → round to 7 g (5 g + 2 g)
30 g monthly IVIG → (30 × 1.37) ÷ 4 = 10.275 g weekly → round to 10 g
40 g monthly IVIG → (40 × 1.37) ÷ 4 = 13.7 g weekly → round to 14 g (10 g + 4 g)
# Schedule transitions
Initiate Xembify ~1 week after the last IVIG dose
Biweekly equivalent: 2 × the weekly dose every 2 weeks
Weekly Xembify dose (g) = (Previous monthly IVIG dose (g) × 1.37) ÷ 4
# Examples
20 g monthly IVIG → (20 × 1.37) ÷ 4 = 6.85 g weekly → round to 7 g (5 g + 2 g)
30 g monthly IVIG → (30 × 1.37) ÷ 4 = 10.275 g weekly → round to 10 g
40 g monthly IVIG → (40 × 1.37) ÷ 4 = 13.7 g weekly → round to 14 g (10 g + 4 g)
# Schedule transitions
Initiate Xembify ~1 week after the last IVIG dose
Biweekly equivalent: 2 × the weekly dose every 2 weeks
What changes on the claim during conversion
| Element | Before (IVIG) | After (Xembify) |
|---|---|---|
| HCPCS | J1459 / J1568 / J1569 / J1561 (etc.) | J1558 |
| Unit basis | 500 mg / unit | 100 mg / unit |
| Admin CPT | 96365 (initial) + 96366 (additional hour) | 96369 + 96370 + 96371 |
| Frequency | Every 3–4 weeks | Weekly (or biweekly) |
| Site of care | Often AIC (POS 49) or HOPD (POS 19/22) | Often home (POS 12) after training |
| Authorization | IVIG PA | Submit new PA for SCIG (most payers) |
Submit a new PA at conversion. Even if the same diagnosis is on file, the SCIG product is
a separate authorization. Include: prior IVIG regimen, IgG trough on IVIG, conversion calculation,
anticipated weekly SCIG dose, and training/home-infusion plan. Same-manufacturer continuity
advantage: if the patient is converting from Gamunex-C IVIG (also Grifols), some payers will accept
the brand transition with reduced documentation given the shared caprylate/chromatography purification platform.
NDC & vial reference FDA NDC Directory verified May 2026
| NDC (10-digit, representative) | Vial size | Volume | Concentration |
|---|---|---|---|
13533-800-15 | 1 g | 5 mL | 200 mg/mL (20%) |
13533-800-20 | 2 g | 10 mL | 200 mg/mL (20%) |
13533-800-25 | 4 g | 20 mL | 200 mg/mL (20%) |
13533-800-30 | 5 g | 25 mL | 200 mg/mL (20%) |
13533-800-40 | 10 g | 50 mL | 200 mg/mL (20%) |
13533-800-50 | 20 g | 100 mL | 200 mg/mL (20%) |
NDC verification: The labeler code 13533 is Grifols Therapeutics. NDCs above are
representative carton/package NDCs — verify the exact NDC printed on the dispensed carton against the
FDA NDC Directory before submitting (Grifols periodically refreshes package configurations). Convert to
11-digit format by zero-padding the product or package segment as your payer requires (e.g., 5-4-2 format).
All Xembify vials are single-dose (single-dose container per CMS terminology). JZ
modifier applies on every claim with no waste; JW applies if any portion of a vial is discarded. Xembify's
1 g, 2 g, 4 g, 5 g, 10 g, and 20 g vial range is the broadest in the 20% SCIG class — minimizing waste
is generally easier than with Hizentra (1/2/4/10 g) or Cuvitru (1/2/4/8/10 g).
Stabilizer: Xembify is glycine-stabilized (not L-proline like Hizentra or Privigen, not
maltose like Cutaquig or Octagam). Glycine is broadly tolerated. Patients with hyperprolinemia syndromes
(avoid Hizentra/Privigen) or diabetes/glucose-monitor concerns (avoid maltose products) often route to a
glycine product like Xembify, Cuvitru, or Gammagard Liquid. Document the stabilizer rationale if it drives
product choice over a payer-preferred alternative.
Phase 2
Code the claim
SC pump infusion family (96369/96370/96371) — not IV, not single-shot SC injection.
Administration codes (96369 / 96370 / 96371) CPT verified May 2026
SC pump infusion family. The most common Xembify admin error is using IV codes (96365/96366) or single-shot SC injection (96372).
| Code | Descriptor | When to use for Xembify |
|---|---|---|
96369 |
Subcutaneous infusion for therapy or prophylaxis (specify substance or drug); initial, up to 1 hour, including pump set-up and establishment of subcutaneous infusion site(s) | Primary code for Xembify. Bill once per session. Includes pump priming and the first SC site. |
96370 |
Subcutaneous infusion for therapy or prophylaxis (specify substance or drug); each additional hour (list separately in addition to code for primary procedure) | For sessions running >60 minutes (most adult Xembify infusions). Bill per additional hour (or substantial fraction). |
96371 |
Subcutaneous infusion for therapy or prophylaxis (specify substance or drug); additional pump set-up with establishment of new subcutaneous infusion site(s) (list separately in addition to code for primary procedure) | When a second pump is added or a new SC infusion site is established mid-session (large doses across multiple body sites). Add-on, not standalone. |
96365 / 96366 |
Therapeutic IV infusion (initial / each additional hour) | NOT appropriate for Xembify. These are IV codes; Xembify is SC. |
96372 |
Therapeutic SC or IM injection (specify substance or drug) | NOT appropriate for Xembify. 96372 is a single-shot manual injection (e.g., Cosentyx, Stelara, B12). Xembify is a pump-driven infusion. |
Top admin-code denial pattern: Provider-side billing systems sometimes auto-populate
96365 (IV therapeutic) for any immune globulin claim. For SCIG products (Xembify, Hizentra, Cuvitru, Cutaquig,
HyQvia), override to 96369/96370/96371. Audit Xembify claims monthly to catch this drift — especially
in practices that also bill Gamunex-C IVIG (J1561) where the IV admin codes are correct.
Home self-administration: When the patient self-infuses at home, the home-infusion
provider bills the per-diem and supplies (S9338 / S9494 / S9559 family or 99601/99602 nursing visits when
a nurse is present). The drug J1558 and the 96369/96370/96371 admin codes are typically billed by the
infusion provider on the same claim under the medical benefit. See
home administration billing.
Modifiers CMS verified May 2026
JZ — required on every Xembify claim with no waste
Effective July 1, 2023, CMS requires the JZ modifier on every single-dose container claim when no drug is discarded. All Xembify vials are single-dose containers. JZ applies on the majority of Xembify claims when the dose maps cleanly to vial sizes (1 g, 2 g, 4 g, 5 g, 10 g, 20 g). Xembify's wider vial range typically reduces waste compared to other 20% SCIGs.
JW — partial-vial waste
JW reports the discarded portion of a single-dose vial. For Xembify, JW applies whenever the dose does not map cleanly to the available vial sizes. Example: a 6 g weekly dose — 1 × 5 g + 1 × 1 g with no waste = JZ. But if a patient receives 13 g and the closest combination is 1 × 10 g + 1 × 4 g (1 g discarded), the discarded mg are reported on a separate JW line. One of JZ or JW must be on every J1558 claim line.
Modifier 25 — same-day E/M
Use modifier 25 on the E/M code when a significant, separately identifiable evaluation and management service is performed on the same day as a Xembify training infusion. Pump training visits routinely justify a modifier-25 E/M.
340B modifiers (JG, TB)
For 340B-acquired Xembify, follow your MAC's current 340B modifier policy. Grifols' billing guide does not provide 340B-specific guidance.
ICD-10-CM by indication FY2026 verified May 2026
Use the most specific code supported by encounter documentation. PI requires IgG-level evidence. Xembify is PI-only on label.
| Indication | ICD-10 family | Documentation requirements |
|---|---|---|
| Common variable immunodeficiency (CVID) | D83.0 – D83.9 | IgG < 5 g/L (or LCD-specified threshold), poor vaccine response, recurrent infections |
| Hypogammaglobulinemia (unspecified) | D80.1 | IgG levels, infection history |
| Selective IgG subclass deficiency | D80.3 | Subclass quantification + functional antibody response |
| X-linked agammaglobulinemia (Bruton) | D80.0 | BTK gene confirmation; pediatric onset |
| Selective IgA deficiency | D80.2 | Generally NOT an SCIG indication on its own (asymptomatic IgA deficiency is monitored, not treated) |
| Other immunodeficiency w/ predominantly antibody defects | D80.8 / D80.9 | Documentation of antibody defect + clinical infections |
| Combined immunodeficiency | D81.x | SCID and variants; usually pediatric |
| Immunodeficiency w/ other major defect | D82.x | Wiskott-Aldrich (D82.0), DiGeorge (D82.1), etc. |
| CIDP (G61.81) | G61.81 | NOT an FDA-approved indication for Xembify. Use Hizentra (J1559), HyQvia (J1575), or IVIG. |
PI documentation is LCD-driven. Most MACs require: (1) IgG level below the LCD threshold,
(2) poor specific antibody response to vaccine challenge (pneumococcal, tetanus), and (3) clinical history
of recurrent serious infections. PI without IgG-level documentation is a routine denial. The same is
true commercially — UHC, Aetna, Cigna, and BCBS plans typically require these three elements.
Off-label CIDP use will be denied. Xembify's FDA approval is PI only (adults + pediatric
≥2 yr). Submitting J1558 with a CIDP diagnosis (G61.81) as the primary indication will trigger automatic
denial at most major payers. For CIDP maintenance, route to Hizentra (J1559)
(the only SCIG with FDA-approved CIDP maintenance), HyQvia (J1575, 2024 CIDP approval), or an IVIG product.
Site of care & place of service Verified May 2026
Xembify's site-of-care distribution mirrors Hizentra and Cuvitru: home (POS 12) is dominant, with ambulatory infusion (POS 49) and physician office (POS 11) used during the initial training period or for patients unable to self-infuse. Hospital outpatient (POS 19/22) is rarely justified for routine Xembify and is the most common site-of-care denial.
| Setting | POS | Claim form | Typical use for Xembify |
|---|---|---|---|
| Patient home (self-infusion) | 12 | CMS-1500 / 837P (medical benefit) or pharmacy claim | Dominant setting after training. 80%+ of stable Xembify patients. |
| Patient home (RN-administered) | 12 | CMS-1500 / 837P with 99601/99602 nursing visits | Patients who cannot self-infuse; intermittent RN visits |
| Ambulatory infusion suite (AIC) | 49 | CMS-1500 / 837P | Initial training (1–3 sessions); ongoing if patient can't self-infuse |
| Physician office | 11 | CMS-1500 / 837P | Training; same-day E/M with infusion |
| Oncology / specialty clinic | 11 / 49 | CMS-1500 / 837P | For patients managed through immunology / hem-onc clinic infrastructure |
| Hospital outpatient (on-campus) | 22 | UB-04 / 837I | Rarely justified. Common site-of-care denial. |
| Hospital outpatient (off-campus PBD) | 19 | UB-04 / 837I | Rarely justified. Common site-of-care denial. |
Site-of-care comparison vs IVIG: Where IVIG is steered into ambulatory and home infusion
out of hospital outpatient, Xembify is steered into home from any other setting. The
payer logic: SCIG is designed for home self-administration, so any clinical setting (including AIC) is
only justified during training or for patients with documented inability to self-infuse.
Home administration billing CMS Home Infusion Therapy verified May 2026
Xembify is a canonical home-infused biologic. The medical-benefit vs DME/specialty-pharmacy decision is the largest reimbursement variable.
Two coverage pathways
| Medical benefit (Part B / commercial medical) | Pharmacy / DME benefit | |
|---|---|---|
| Drug bill | J1558 on CMS-1500 / 837P from home-infusion provider | NDC-based pharmacy claim from specialty pharmacy; no J1558 |
| Admin codes | 96369 + 96370 + 96371 when infused with provider involvement | None — patient self-administered; supply only |
| Per-diem services | S9338 (infusion therapy, immune globulin, per-diem) and related S-codes | Bundled into specialty pharmacy supply fee |
| Nursing visits (when applicable) | 99601 (initial home infusion visit, up to 2 hr) / 99602 (each additional hour) | Not billed under pharmacy benefit |
| Pump & supplies | Often bundled into S-code per-diem | Bundled into specialty pharmacy fee or billed under DME |
| Typical payer | Medicare Part B; commercial medical plans w/ home-infusion benefit | Some commercial plans for stable self-administered SCIG; limited Medicare role |
| Patient cost-share | Medical deductible + coinsurance (often 20% pre-Medigap) | Pharmacy copay tier (specialty) |
Medicare Part B SCIG coverage
- Medicare Part B covers Xembify plus home-infusion services for PI under the SCIG demonstration / Home Infusion Therapy Services benefit (DME MAC jurisdiction historically; transitioning under the 21st Century Cures Act home-infusion framework).
- Verify your DME MAC's current SCIG LCD before submitting (Noridian, CGS, Palmetto, NHIC).
- Xembify has no NCD; coverage falls under MAC LCDs for SCIG.
Commercial home-infusion pathway
- Most commercial plans cover Xembify under the medical benefit with a contracted home-infusion provider (Coram / CVS Health, Option Care Health, Optum Infusion, BriovaRx, etc.).
- Some plans require step therapy through the pharmacy benefit specialty pharmacy first — verify per plan.
- UHC, Aetna, Cigna, and BCBS plans generally pre-authorize the home-infusion provider as part of the Xembify PA.
- Grifols PathConnect (1-855-477-2672) provides benefits investigation and assists with home-infusion provider assignment.
The most common home-infusion billing error: billing the per-diem (S9338) without the
drug (J1558), or vice versa. Both lines must be on the claim — payer reconciles the per-diem to the
underlying drug administration. Missing either line triggers automatic denial.
Pump and supplies: The mechanical infusion pump used for Xembify (commonly the
CRONO-S, Freedom60, or Eitan equivalent) is typically supplied by the home-infusion provider or DME
supplier. Most commercial and Medicare home-infusion benefits bundle the pump and tubing/needle supplies
into the per-diem rate. Itemized DME billing for the pump (E0784 or similar) is rarely appropriate when
the per-diem is billed.
Claim form field mapping Grifols billing guide 2026
| Information | CMS-1500 box | Notes |
|---|---|---|
| NPI | 17b / 24J | Rendering provider (or home-infusion provider's NPI) |
| NDC qualifier + 11-digit NDC + UoM + qty | 24A shaded area | N4 + 11-digit Xembify NDC + ML + total volume in mL |
| HCPCS J1558 + JZ (or JW for waste) | 24D (drug line) | One of JZ or JW required on every claim |
| Drug units | 24G | mg administered ÷ 100 (e.g., 10,000 mg = 100 units) |
| CPT 96369 (admin line, primary) | 24D (admin line) | Initial up to 1 hr SC infusion + pump set-up + first SC site |
| CPT 96370 (admin line, addl hour) | 24D (additional admin line) | Each additional hour beyond 60 min; list separately |
| CPT 96371 (addl pump set-up) | 24D (additional admin line) | Additional pump or new SC site, list separately |
| S9338 (per-diem home infusion) | 24D (services line) | For home-infusion provider claims (medical benefit) |
| 99601 / 99602 (nursing visits) | 24D | When RN administers (not patient self-infusion) |
| ICD-10 | 21 | D80.x / D81.x / D82.x for PI (Xembify is PI-only) |
| PA number | 23 | Required by all major payers for SCIG |
Phase 3
Get paid
PA documentation: IgG levels, vaccine challenge, infection history, training plan.
Payer LCDs & PA criteria Reviewed May 2026
All major payers PA SCIG. UHC and several BCBS plans actively prefer SCIG over IVIG for stable PI; cost-conscious plans may prefer Xembify within the SCIG class.
| Payer | PA? | Key criteria | Brand positioning |
|---|---|---|---|
| UnitedHealthcare SCIG / Immune Globulin medical policy |
Yes | PI: IgG level + vaccine challenge + recurrent infections. Training plan + home-infusion provider authorized at PA. | Xembify, Hizentra, and Cuvitru all listed. Cost-conscious policies may favor Xembify (lowest 20% SCIG ASP). |
| Aetna CPB Immune Globulin |
Yes | PI criteria mirror UHC. Site-of-care prefers home or AIC for SCIG. | Generally allows clinician choice across SCIG brands |
| Cigna Coverage Policy 1006 (Immune Globulin) |
Yes | PI standard criteria; home-infusion benefit detailed in policy | SCIG and IVIG covered at parity for stable patients; Xembify, Hizentra, Cuvitru all on policy |
| BCBS plans Vary by plan |
Yes | Generally aligned with FDA label and major commercial peer policies | Plan-specific; some plans prefer the lowest-cost 20% SCIG option (often Xembify) |
| Medicare (Part B) DME MAC SCIG LCD + Home Infusion Therapy Services |
Often (DME) | PI well-covered for FDA-approved on-label use | Coverage parity across SCIG brands; clinical choice driven by patient/clinician |
PA documentation checklist (PI)
- IgG level (LCD-specific threshold, often < 5 g/L or < 500 mg/dL)
- Specific antibody response to vaccine challenge (pneumococcal polysaccharide, tetanus toxoid)
- Recurrent serious infection history (otitis, sinusitis, pneumonia, etc.) with treatment dates
- Conversion calculation if transitioning from IVIG (1.37 factor)
- Home-infusion training plan + designated provider (commercial)
- Patient/caregiver capability for self-administration (or documented inability if home isn't appropriate)
Brand-switch documentation (within SCIG class)
- If switching from Hizentra, Cuvitru, or another SCIG to Xembify: document tolerability/efficacy on prior product, payer formulary requirement (if applicable), and stabilizer rationale (glycine vs proline vs maltose).
- Cost-driven switches at the payer level: payer may mandate Xembify for new starts as the lowest-cost 20% SCIG; document the formulary-driven brand selection in the PA narrative.
Medicare reimbursement CMS Q2 2026 (live)
Quarterly ASP from CMS Part B Drug Pricing File. Refreshes automatically each quarter.
Q2 2026 payment snapshot — J1558
Effective April 1 – June 30, 2026 · 1 unit = 100 mg
ASP + 6%
$15.367
per 100 mg unit (~$0.154/mg)
10 g weekly dose
$1,536.70
100 units × ASP+6%
Per gram
$153.67
10 units (1 g) × ASP+6%
Annualized cost: 10 g weekly × 52 weeks = ~$79,908/year
(Medicare ASP+6%) for a typical 70 kg PI patient at 140 mg/kg/week. Larger patients scale proportionally.
After ~2% sequestration: ~$78,310/year actual paid.
Per-mg comparison across SCIG class (Q2 2026 ASP+6%)
- Cuvitru (J1555): ~$0.176/mg — highest 20% SCIG
- Xembify (J1558): ~$0.154/mg — this product
- Hizentra (J1559): ~$0.145/mg
- Cutaquig (J1551, 16.5% maltose): ~$0.139/mg — lowest SCIG, but different concentration class
- HyQvia (J1575, 10% IG + hyaluronidase): different unit basis — not directly comparable per-mg
- Gamunex-C SC (J1561): 500 mg unit basis (IV code applied to SC use); per-mg ~$0.099 but different admin codes
Within the 20% SCIG class, Xembify prices between Hizentra and Cuvitru on per-mg ASP — positioned for cost-conscious payer formularies that want a glycine-stabilized 20% product without paying the Cuvitru premium. Across all SCIG products, Xembify per-gram ASP runs roughly 1.5–2× the per-gram price of standard IVIG products due to the 20% concentration manufacturing premium and self-administration convenience.
Coverage
No NCD specific to Xembify. Coverage falls under MAC LCDs for SCIG (immune globulin subcutaneous) and the Home Infusion Therapy Services benefit. All MACs cover J1558 for FDA-approved on-label PI indications with appropriate ICD-10 (D80.x / D81.x / D82.x) and clinical documentation. CIDP coverage is NOT supported for J1558 — route to J1559 (Hizentra) or J1575 (HyQvia) for CIDP.
Patient assistance — Grifols PathConnect Grifols verified May 2026
- Grifols PathConnect (Xembify): 1-855-477-2672 — benefits investigation, prior authorization assistance, appeal support, training resources, home-infusion coordination
- Xembify Co-Pay Assistance Program: commercial copay support for eligible commercially-insured patients (excludes Medicare, Medicaid, federal program patients)
- Grifols Patient Assistance Program: free product for uninsured / underinsured patients meeting income requirements
- Independent foundations for Medicare patients: PAN Foundation (immunodeficiency funds), HealthWell Foundation, Patient Advocate Foundation — verify open funds quarterly
- IDF (Immune Deficiency Foundation): primaryimmune.org — patient education, advocacy, resources
- Web: xembify.com / grifols.com
Need to model what a specific Xembify patient will actually pay after copay assistance, deductible,
coinsurance, and OOP max? Run a CareCost Estimate — J1558 pre-loaded.
SCIG brand interchangeability & cost matrix Verified May 2026
SCIG products are NOT interchangeable for billing. Each brand has its own HCPCS, NDC, ASP, and concentration. Match the code to the product actually infused. Cost positioning matters when payers mandate brand selection.
| HCPCS | Brand | Mfr | Concentration | Stabilizer | Unit basis | Per-mg ASP+6% (Q2 2026) | FDA-approved indications |
|---|---|---|---|---|---|---|---|
J1558 |
Xembify (this page) | Grifols | 20% liquid SC | Glycine | 100 mg | ~$0.154 | PI (adult + ped ≥2) |
J1559 |
Hizentra | CSL Behring | 20% liquid SC | L-proline | 100 mg | ~$0.145 | PI (adult + ped ≥2); CIDP maintenance (adult) |
J1555 |
Cuvitru | Takeda | 20% liquid SC | Glycine | 100 mg | ~$0.176 | PI (adult + ped ≥2) |
J1551 |
Cutaquig | Octapharma | 16.5% liquid SC | Maltose | 100 mg | ~$0.139 | PI (adult + ped ≥2) |
J1575 |
HyQvia | Takeda | 10% IG + recombinant hyaluronidase | Glycine | 100 mg IG (per HCPCS) | (separate basis) | PI; CIDP maintenance (adult, 2024) — facilitated SC, monthly dosing possible |
J1561 |
Gamunex-C (sister Grifols product) | Grifols | 10% liquid (IV or SC use) | Glycine | 500 mg (IV basis applies even when given SC) | ~$0.099 | PI (IV/SC), ITP (IV), CIDP (IV) |
| IVIG companion class (500 mg unit basis, IV admin codes 96365/96366): | |||||||
J1459 |
Privigen | CSL Behring | 10% liquid IV | L-proline | 500 mg | ~$0.080/mg | PI, ITP, CIDP |
J1569 |
Gammagard Liquid | Takeda | 10% liquid IV | Glycine | 500 mg | ~$0.085/mg | PI, MMN |
Cost-positioning takeaway: Among 20% SCIGs, Xembify prices below Cuvitru and slightly
above Hizentra. For payers running a cost-driven 20% SCIG mandate, Xembify is often the lowest-cost
glycine-stabilized 20% option (Hizentra is proline-stabilized; some patient populations need glycine).
Cutaquig is the lowest per-mg SCIG overall but uses a 16.5% concentration with maltose stabilization
(different volume requirements per dose, glucose-monitor concerns).
Three brand-related billing patterns to avoid:
- Wrong code, right route: billing J1558 (Xembify) for a patient who actually received Hizentra (J1559) or Cuvitru (J1555) is a denial trigger and a compliance issue. ASP differences create a $/unit delta auditors will catch.
- Wrong unit basis when crossing routes: applying the IVIG 500 mg/unit basis to a SCIG product (or vice versa) under-reports or over-reports the dose by 5×. The most common crossover error is on Gamunex-C (J1561) when given SC — it still uses the 500 mg/unit basis because the HCPCS is the IV code. This trap is particularly common in Grifols-loyal practices that infuse both Xembify and Gamunex-C SC.
- Right code, payer-mandated different brand: some payers contract preferentially with specific SCIG brands. UHC may steer to Xembify on cost grounds while Aetna may require Hizentra or Cuvitru on the next plan. Verify the payer's preferred SCIG brand on every PA; do not assume continuity across payers.
When clinical brand justification is needed
- Diabetes / renal: avoid maltose-stabilized SCIG (Cutaquig) due to interference with some glucose monitors and renal precautions; Xembify (glycine), Hizentra (proline), and Cuvitru (glycine) all preferred.
- Hyperprolinemia: avoid proline-stabilized products (Hizentra, Privigen); prefer glycine (Xembify, Cuvitru, Gammagard Liquid) or maltose (Cutaquig).
- Tolerability history: if the patient had local site reactions on one SCIG brand, switching to another stabilizer/concentration combination is a common clinical strategy — document the rationale.
- Vial-waste optimization: Xembify's 5 g and 20 g vials (unique in the 20% SCIG class) often produce cleaner waste profiles for ~50–70 kg patients on weekly dosing or for very high-dose CIDP-converted patients (off-label, but vial-fit considerations apply if patient is being managed under a different SCIG with CIDP coverage).
- Manufacturer continuity: patients converting from Gamunex-C IVIG (Grifols) often appreciate transitioning to Xembify (also Grifols, same caprylate/chromatography purification platform) for product-line consistency.
- Monthly dosing preference: consider HyQvia (J1575) which uses recombinant hyaluronidase to enable larger-volume monthly SC infusions vs the weekly Xembify schedule.
Phase 4
Fix problems
Unit math, IV-vs-SC admin code confusion, and missing PA documentation are the top three.
Common denials & how to fix them
| Denial reason | Common cause | Fix |
|---|---|---|
| Unit math wrong (under by 5x) | IVIG 500 mg/unit basis applied to J1558 | Recalculate: J1558 = 100 mg/unit. 10 g = 100 units. Resubmit corrected. |
| Unit math wrong (over by 100x) | 1 mg/unit (per-mg) basis applied; 10,000 units submitted for 10 g | Recalculate: J1558 = 100 mg/unit. 10 g = 100 units. Resubmit corrected. |
| Wrong admin code (96365) | IV therapeutic code billed instead of SC pump infusion | Resubmit with 96369 (initial) + 96370 (each addl hour) + 96371 (addl pump set-up if used). |
| Wrong admin code (96372) | Single-shot SC injection code billed instead of pump infusion | Resubmit with 96369 + 96370 + 96371. 96372 is for one-time SC injections (Cosentyx, Stelara, B12), not pump-driven SCIG. |
| JZ/JW missing | Single-dose container claim without modifier | Resubmit with JZ if no waste, JW with discarded units if partial vial. |
| PI dx without IgG documentation | D80.x submitted without IgG level, vaccine challenge, or infection history | Submit complete LCD-required documentation and request retroactive PA. |
| CIDP dx with J1558 | G61.81 submitted with Xembify (Xembify is PI-only on label) | Switch to Hizentra (J1559) or HyQvia (J1575) for CIDP, or to an IVIG product. Xembify CIDP claims will be denied as off-label. |
| Site of care (HOPD) | Xembify billed from POS 19/22 outside of training period | Move to home (POS 12), AIC (POS 49), or office (POS 11). Document medical necessity if HOPD truly required. |
| Per-diem without drug or vice versa | S9338 billed without J1558 (or J1558 without S-code on home claim) | Both lines required on home-infusion claims. Resubmit complete claim. |
| SCIG not preferred brand | Xembify billed when payer requires Hizentra / Cuvitru / Cutaquig | Verify formulary; switch product or submit non-formulary exception with clinical justification (stabilizer rationale, prior tolerability history). |
| No new PA at IVIG → SCIG conversion | Old IVIG PA used for new Xembify claim | Submit fresh PA with conversion calculation, training plan, and home-infusion provider designation. |
| NDC mismatch | 10-digit NDC submitted in 11-digit field, or wrong package configuration | Verify Grifols package NDC against current dispensed carton. Use 11-digit zero-padded format per payer spec. |
Frequently asked questions
What is the HCPCS code for Xembify and what is the unit basis?
Xembify is billed under HCPCS J1558 — "Inj. xembify, 100 mg." Each 100 mg of IgG equals
one billable unit. This is NOT the IVIG 500 mg/unit basis used by J1459, J1568, J1569,
J1561, etc., and it is NOT a per-mg basis. A 10 g (10,000 mg) weekly dose bills as 100 units of J1558.
What administration CPT codes do I use for Xembify?
Use 96369 (subcutaneous infusion, initial up to 1 hr, including pump set-up and first SC
site) for the primary code, plus 96370 (each additional hour) for sessions running >60 min,
and 96371 (additional pump set-up + new SC site) when a second pump or site is initiated.
Do NOT bill 96365/96366 (those are IV) and do NOT
bill 96372 (that is a single-shot SC injection, not a pump infusion).
How does Xembify differ from Gamunex-C, Hizentra, or Cuvitru?
Xembify is Grifols' 20% subcutaneous immune globulin (caprylate/chromatography purified, glycine stabilized), FDA-approved 2019 for primary humoral immunodeficiency in adults and pediatric patients aged 2 years and older. It is the SC sister to Gamunex-C (Grifols J1561 IVIG/SCIG, 10%). Hizentra (CSL Behring J1559, 20% L-proline) and Cuvitru (Takeda J1555, 20% glycine) are the direct same-class competitors. All three 20% SCIG products bill at 100 mg per unit and use the same 96369/96370/96371 admin code family. Xembify is positioned as the lowest-cost 20% SCIG vs Cuvitru; Hizentra has the only FDA-approved CIDP indication in the SCIG class.
How do I convert a monthly IVIG dose to a weekly Xembify dose?
Per the FDA Xembify label: weekly Xembify dose = (previous monthly IVIG dose × 1.37) ÷ 4. The 1.37 factor accounts for differences in bioavailability and trough kinetics between IV and SC routes. Example: 30 g IVIG monthly converts to (30 × 1.37) ÷ 4 = 10.275 g weekly Xembify, rounded to 10 g per week. Initiate Xembify ~1 week after the last IVIG dose. See the conversion section.
What is the Medicare reimbursement for J1558?
For Q2 2026, the Medicare Part B payment limit for J1558 is $15.367 per 100 mg unit (ASP + 6%), or roughly $154 per gram. A 10 g weekly dose bills as 100 units and reimburses at $1,536.70 per infusion. Annualized at 52 weekly infusions: ~$79,908/year for a 10 g/week patient. Sequestration (~2%) reduces actual paid to roughly ASP + 4.3%.
Can I bill Xembify for a CIDP patient?
No — Xembify is not FDA-approved for CIDP as of 2026. The only SCIG with an FDA-approved CIDP maintenance indication is Hizentra (J1559); HyQvia (J1575) added a CIDP indication in 2024. Off-label CIDP use of Xembify will be denied by most major payers. Route CIDP patients to Hizentra, HyQvia, or an IVIG product depending on stage of treatment.
Is Xembify billed as a medical benefit or a pharmacy/DME benefit when self-administered at home?
Both pathways exist. Medical benefit (Part B / commercial medical): bill J1558 + 96369/96370/96371 + S9338 per-diem from the home-infusion provider on a CMS-1500/837P. Pharmacy/specialty: NDC-based pharmacy claim with no J1558 line. Medicare Part B typically covers Xembify plus home-infusion services for PI under the SCIG demonstration / Home Infusion Therapy Services benefit. Verify per payer — UHC, Aetna, BCBS, and Medicare DME MACs all have product-specific home-infusion policies. See home administration billing.
What ICD-10 codes support Xembify coverage?
For PI: D80.x (immunodeficiency w/ predominantly antibody defects, e.g., D80.0 X-linked, D80.1 hypogamma, D80.3 IgG subclass, D83.x CVID family), D81.x (combined immunodeficiencies), D82.x (immunodeficiency with other major defects). Xembify is FDA-approved for PI only — do NOT submit G61.81 (CIDP) with J1558.
Where do I get Xembify patient assistance?
Grifols PathConnect: 1-855-477-2672. Provides benefits investigation, prior authorization assistance, copay support for commercially-insured patients, free product through the Grifols Patient Assistance Program for income-qualifying uninsured/underinsured patients, and home-infusion coordination. For Medicare patients, route to PAN Foundation or HealthWell Foundation immunodeficiency funds. See the patient assistance section.
Reference
Sources & methodology
Every claim on this page is sourced. Methodology and review history below.
Source documents
- FDA — Xembify (Immune Globulin Subcutaneous, Human-klhw, 20% Liquid)
- Xembify HCP & patient site — Grifols
- Grifols — Manufacturer site (PathConnect support)
- CMS — Medicare Part B Drug ASP Pricing File
- CMS — Home Infusion Therapy Services (21st Century Cures Act framework)
- Immune Deficiency Foundation (IDF)
- AAAAI — Use of Human Immunoglobulin Practice Parameter
- UnitedHealthcare — Immune Globulin / SCIG Medical Policy
- Aetna — CPB Immune Globulin
- Cigna — Coverage Policy 1006 (Immune Globulin)
- FDA National Drug Code Directory (Xembify NDCs)
About this page
We maintain this page as a living reference. Medicare ASP pricing 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 source document changes.
Found an error? Email hello@carecostestimate.com.
Refresh cadence
| Element | Cadence | How it's refreshed |
|---|---|---|
| Medicare ASP pricing | 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 immune globulin / SCIG medical policies. |
| HCPCS / CPT / modifier rules | Annual | Reviewed against CMS HCPCS quarterly files and AMA CPT releases. |
| NDC, dosing, FDA label, indication | Event-driven | Tied to Grifols document version + FDA label revision date. |
| SCIG brand cost matrix | Quarterly | Refreshed each ASP cycle alongside the per-mg comparison table. |
Reviewer
Pending SME review. This page is staff-authored from primary sources (FDA, CMS, Grifols,
payer documents — 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, especially the unit-basis math, SC vs IV admin code selection, and the PI-only indication scope
(Xembify does not cover CIDP).
Change log
- — Initial publication. ASP data: Q2 2026. Manufacturer source: Grifols 2026. FDA label: PI July 2019. Cross-referenced with Hizentra, Cuvitru, Cutaquig (SCIG companions); Gamunex-C (sister Grifols product); Privigen, Gammagard Liquid (IVIG companions).
Methodology
Every claim on this page is sourced inline. Pricing reflects the current CMS Part B Drug ASP Pricing File. Payer policies are read directly from each payer's published medical policy documents. Indication, dosing, and conversion math are verified against the current FDA Xembify label. We do not paraphrase from billing-software vendor blogs.