HCPCS code J2170 – Injection, mecasermin

Key takeaways

HCPCS code J2170 describes injection, mecasermin, 1 mg, and you bill one unit for each milligram given.

Medicare Part B pays J2170 at average sales price plus 6%, and that rate changes every calendar quarter.

Missing prior authorization is the leading cause of J2170 denials, so secure it before the first dose.

Increlex ships in a multi-dose vial, so the JW and JZ wastage modifiers never apply to J2170.

Practice management software like Pabau tracks J2170 units, prior authorization status, and NDC rules in one place.

Drug overview: Mecasermin (Increlex)

Mecasermin is a recombinant human IGF-1 produced by DNA technology. The FDA approved Increlex for two indications, both involving children who cannot produce adequate IGF-1. Those indications govern medical necessity documentation and the ICD-10 codes that pair with J2170.

• Severe primary IGF-1 deficiency (SPIGFD): height and basal IGF-1 standard deviation scores of -3.0 or lower, with normal or elevated growth hormone
• Growth hormone gene deletion with neutralizing antibodies: children who have developed antibodies to exogenous growth hormone and no longer respond to GH therapy

Those thresholds are stricter than the growth percentiles many payer policies quote, so check the current Increlex label when you assemble the clinical evidence. Mecasermin is given by subcutaneous injection, usually twice daily. It is not approved for short stature from other causes, and off-label use will not meet payer medical necessity criteria for J2170.

Billing units and how to report J2170

Each unit of J2170 equals 1 mg of mecasermin. Bill one unit for every milligram administered, so a 4 mg dose is 4 units. Under-reporting and over-reporting both create compliance exposure. Map the dose to units at the time of service, not at the end of the month.

Wastage modifiers do not belong on J2170: Increlex ships only as a 40 mg/4 mL multi-dose vial. CMS excludes multi-dose vials from its discarded-drug policy, so modifiers JW and JZ have no place on a J2170 line. Bill the milligrams the patient actually received.

Fee schedule and Medicare reimbursement rates

Medicare reimburses J2170 under the Part B drug benefit using average sales price (ASP) plus 6%. This applies when mecasermin is given in a physician office or outpatient setting. ASP-based rates change each calendar quarter, so verify the current payment limit in the CMS Physician Fee Schedule lookup tool before you submit.

Mecasermin is a high-cost specialty biologic, and Medicaid rates for it vary widely by state. Never quote a dollar figure to a family without first checking the current quarterly ASP file and your contracted rate.

Prior authorization requirements

Most commercial payers and many Medicare Advantage plans require prior authorization for J2170, given what a course of Increlex costs. Traditional Medicare Part B generally does not, though Medicare Administrative Contractors (MACs) may publish Local Coverage Determinations (LCDs) with their own criteria. Running insurance eligibility verification before the first dose prevents the most common J2170 denials.

Build the authorization workflow before the drug is ordered rather than after. A typical request includes:

• Confirmed diagnosis of severe primary IGF-1 deficiency, or GH gene deletion with neutralizing antibodies
• Basal serum IGF-1 standard deviation score of -3.0 or lower for age and sex
• Height standard deviation score of -3.0 or lower, with documented growth velocity
• Prescriber specialty, which is typically pediatric endocrinology
• Evidence of adequate growth hormone secretion, to rule out GH deficiency
• Failure of or contraindication to growth hormone therapy, where applicable

Requirements differ by payer and by plan year. Read the payer’s specialty drug policy before you submit the authorization request.

Documentation requirements and medical necessity

Thin documentation is a top denial driver for J2170. Mecasermin is indicated for two narrow clinical scenarios, so the record has to establish one of them plainly. That work happens in the clinical chart, not on the claim form.

• Diagnosis documentation: chart notes confirming severe primary IGF-1 deficiency or GH gene deletion with neutralizing antibodies, supported by laboratory evidence
• Laboratory values: serum IGF-1 results with the reference range, the date of the test, and the patient’s age
• Growth parameters: height, weight, and growth velocity measurements compared with age and sex norms
• Prescriber credentials: notes that state the specialty of the ordering provider, since pediatric endocrinology is the norm
• Treatment plan: a dosing regimen aligned with the FDA-approved weight-based dosing
• Response monitoring: follow-up growth measurements that confirm ongoing medical necessity

If a MAC has issued an LCD for mecasermin in your jurisdiction, the documentation must satisfy those criteria as well. Check your MAC website for current LCDs affecting J2170 coverage.

ICD-10 diagnosis codes for mecasermin claims

The diagnosis codes on a J2170 claim have to support the FDA-approved indications for mecasermin. A growth-related code that does not match the clinical documentation creates medical necessity exposure. The codes below are the ones most often paired with J2170.

The diagnosis has to reflect the FDA-approved indication. Do not reach for a generic short stature code such as R62.52 without documented endocrine disease, because it will not satisfy medical necessity for J2170. Endocrine and metabolic diagnoses sit in Chapter 4 of the code set. Our ICD-10-CM code index covers the families you will use alongside this drug.

NDC to HCPCS crosswalk for mecasermin

Many payers, including most state Medicaid programs, require the National Drug Code (NDC) on J2170 claim lines. Report it in the 11-digit format, using 5-4-2 segmentation, matched to the vial presentation dispensed. Increlex is supplied as a 40 mg/4 mL (10 mg/mL) multi-dose vial for subcutaneous injection.

NDC reporting requirements vary between payers. Medicare Part B traditionally does not ask for the NDC on the claim form, while many commercial payers and Medicaid programs do. Where it is required, report it in loop 2410 of the 837P transaction with the qualifier “N4”, plus the quantity and the unit of measure.

Related HCPCS codes and when to use them

Knowing when J2170 is the correct code, and when a neighboring code is, prevents misrouted claims. The AAPC HCPCS code lookup is a quick way to confirm current descriptors and crosswalks before you commit a claim line.

Common billing mistakes with J2170

J2170 claims fail more often than standard office visit codes, because a specialty drug carries more conditions on the line. The five checks below run in the order the work happens, from the authorization request through to the modifier field.

• Incorrect unit calculation: billing 1 unit for a multi-milligram dose is the most common error. Bill one unit per 1 mg of mecasermin administered.
• Missing NDC: where a payer requires the NDC on the claim line, omitting it produces an automatic rejection. Check the payer’s EDI requirements before the first claim.
• Appending JW or JZ: Increlex comes in a multi-dose vial, and CMS excludes multi-dose vials from discarded-drug billing. A wastage modifier on a J2170 line invites a rejection.
• Submitting without confirmed authorization: administering Increlex before the authorization number is in hand leads to a denial that is rarely overturned.
• Thin medical necessity documentation: chart notes that reference “short stature” without IGF-1 results and a specific diagnosis will not satisfy payer criteria.
• Using J3490 instead of J2170: some billers default to unclassified drug codes. Mecasermin has its own HCPCS code and must be billed with it.

Each of these is cheaper to catch at the point of service than after a denial. Authorization tracking and an NDC reference inside the billing workflow remove most of the manual checking that produces them.

How Pabau keeps J2170 claims clean

Most practices track specialty drug billing across a spreadsheet, a payer portal, and the clinical chart. The authorization number lives in one place, the NDC in another, and the administered dose in a third. Reconciling the three by hand before each claim is where J2170 units and modifiers go wrong.

Pabau is practice management software that holds the appointment, the clinical note, and the claim in a single patient record. Its medical claims management tools track HCPCS units, authorization status, and payer-specific NDC rules against the encounter that generated them. Billing staff work from one screen instead of three.

Fewer claims come back for a missing number, and your team spends less time rebuilding a line item weeks after the injection. For a drug this expensive, one prevented denial pays for a lot of admin time.

Manage specialty drug claims without the spreadsheets

Pabau tracks HCPCS billing units, prior authorization status, and NDC requirements for specialty injectables in one place. See how it works for your practice.

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Conclusion

A J2170 claim is won or lost before the injection. Three things carry most of them through on the first pass. You need the authorization in hand, a diagnosis the chart genuinely supports, and one unit billed per milligram.

The J2170 detail worth remembering is the vial. Increlex is a multi-dose presentation, so a JW or JZ modifier that reads as diligence on other J-codes becomes an error here. Book a demo to see how Pabau tracks authorizations, units, and NDCs for every specialty injectable your practice bills.

Continue your research

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Looking for a structured approach to superbill accuracy? How to create accurate superbills walks through the documentation fields that prevent rejections on specialty injectable claims.

Checking coverage before a high-cost injection? Insurance eligibility verification sets out what to confirm with the payer before the first dose is drawn up.

Want fewer rejections across every claim you send? What makes a clean claim explains the fields payers check first and how to get them right at the point of service.

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