CPT code 84146: Single quantitative measurement of prolactin (PRL)

CPT code 84146 is the billing code for a quantitative prolactin (PRL) assay on serum or plasma. It sits in the chemistry section of the AMA’s CPT code set. One unit covers one prolactin result, and Medicare pays it under the Clinical Laboratory Fee Schedule (CLFS).

Claims on 84146 usually fail on the supporting details rather than the code itself. The usual causes are a missing ICD-10 link, a payer frequency limit already reached, or an ordering provider who isn’t enrolled with the payer.

This reference covers the covered diagnoses, Medicare rates, medical necessity rules, companion codes and the denial patterns that come up most often on 84146.

Key takeaways

CPT 84146 is the only code for a quantitative prolactin assay on serum or plasma, because CPT has no separate fractionated prolactin code.

Covered indications include hyperprolactinemia (E22.1), amenorrhea, galactorrhea, infertility workups and pituitary adenoma monitoring.

Medicare pays 84146 under the Clinical Laboratory Fee Schedule, and the lab that runs the assay bills it, not the office that draws blood.

Medi-Cal updated its ICD-10 diagnosis code range for prolactin level testing, so covered-code lists from before 2024 may no longer reflect current policy.

In Pabau’s claims software, 84146 claims go out electronically through Claim.MD after an eligibility check, so coverage problems surface before submission.

CPT code 84146: Quick reference

Before building any claim line, confirm these identifiers match your practice’s lab order and payer contract.

What CPT code 84146 covers

CPT 84146 covers a single quantitative measurement of prolactin (PRL) from a serum or plasma specimen. One unit of 84146 corresponds to one prolactin result reported by the performing lab.

CPT has no separate code for fractionated prolactin, so a macroprolactin reflex by PEG precipitation is also reported under 84146. The code doesn’t apply when prolactin is reported inside a panel code that already includes it.

According to the American Medical Association’s CPT code set, the official descriptor is simply “Prolactin.” That brief label covers every quantitative immunoassay method labs use. The clinical indications covered under this single code include:

• Hyperprolactinemia evaluation (excess prolactin production)
• Amenorrhea workup, including secondary amenorrhea and oligomenorrhea
• Galactorrhea investigation (unexplained breast milk production outside pregnancy)
• Infertility evaluation in both female and male patients
• Monitoring of known prolactinoma (pituitary adenoma) during treatment
• Male hypogonadism with unexplained low testosterone
• Suspected hypopituitarism

Clinical indications and when to order CPT 84146

The prolactin CPT code is ordered when a clinician suspects abnormal PRL production is driving a patient’s symptoms. The payer’s question is always the same: Does the clinical picture justify this test on this date? Documentation must answer that question before the claim goes out.

In practices that run hormonal panels, prolactin is a standard first-line test in reproductive evaluation. Common ordering scenarios by specialty include:

• Endocrinology: Hyperprolactinemia, pituitary adenoma monitoring, dynamic function testing
• Obstetrics and gynecology: Amenorrhea, oligomenorrhea, galactorrhea, anovulatory infertility
• Reproductive endocrinology: Infertility workup, ovulation induction evaluation
• Internal medicine / primary care: Unexplained lactation, initial hormonal evaluation prior to specialist referral
• Urology / men’s health: Male infertility, hypogonadism with suspected pituitary involvement

Repeat testing during prolactinoma treatment is clinically appropriate and separately billable, but requires distinct documentation for each encounter. Payers differ on how often they will pay for repeat assays, typically from quarterly to annually depending on the plan.

Covered ICD-10 diagnosis codes for CPT 84146

A non-covered or missing ICD-10 code is the most common reason 84146 claims are rejected. The table below lists the ICD-10-CM codes Medicare and commercial payers most often accept as medical necessity support for prolactin testing.

Coverage varies by MAC jurisdiction and commercial plan, so check your payer’s LCD before billing. Our ICD-10-CM code library has the full descriptor for each code below.

Medi-Cal updated its ICD-10 diagnosis code range for prolactin level testing, per a XIFIN Billing Beat notice. Practices billing California Medicaid should check their covered-code list against the current policy. Some previously covered codes may have been removed and new ones added.

Medical necessity requirements and LCD/NCD coverage

CPT 84146 has no national coverage determination (NCD) from CMS. Coverage is governed by Local Coverage Determinations (LCDs) issued by the Medicare Administrative Contractors (MACs) in each jurisdiction. No single LCD applies nationwide, which means a code covered under Noridian’s LCD may not appear on Novitas’s list, and vice versa.

Running insurance eligibility verification before ordering prolactin testing lowers the risk of a test your payer won’t cover on that date. Key documentation requirements across most payers include:

• Clinical indication in the note: The ordering provider’s note must state the symptom or diagnosis driving the order, not just a test name.
• Supported ICD-10 linkage: The diagnosis code on the claim must match an ICD-10 code listed as covered under the applicable LCD.
• Frequency compliance: Most payers limit reimbursement for repeat prolactin testing. Exceeding the allowed interval without a documented clinical change is a denial trigger.
• Ordering provider enrollment: The provider ordering the test must be enrolled with the payer billed. Orders from non-enrolled providers generate automatic denials.

Prior authorization is not routinely required for CPT 84146 under traditional Medicare fee-for-service, but Medicare Advantage plans vary widely. Commercial payers may require prior auth for repeat testing beyond a defined interval, particularly for prolactinoma monitoring. Verify at the plan level, not the product level.

CPT code 84146 Medicare fee schedule and reimbursement

CPT 84146 is reimbursed under the CMS Clinical Laboratory Fee Schedule (CLFS), not the Physician Fee Schedule (PFS). That applies when an independent or hospital outpatient laboratory performs the test, and practices billing as the performing lab should reference the annual CLFS update.

Physician offices that collect the specimen but send it to a reference lab typically don’t bill 84146 directly. They bill the blood draw under CPT 36415 instead.

Use the CMS Clinical Laboratory Fee Schedule files to find the current national limitation amount for 84146. Rates update each January 1, so check the latest file before billing or contracting.

Commercial payers typically reimburse prolactin testing at 80 to 150 percent of the Medicare CLFS rate, with wide variation by contract tier and region.

Pabau, the practice management platform we build, sends claims for lab chemistry codes like 84146 electronically through Claim.MD, its US clearinghouse partner. The same connection runs 270/271 eligibility checks and tracks claim status.

How to document and bill CPT 84146 correctly

Clean claims for 84146 need four elements in order before submission: The clinical note, the ICD-10 linkage, the place of service and the performing-lab identification. Missing any one of them produces a denial that someone has to rework by hand.

Follow these steps when building a clean claim for a prolactin assay:

1. Document the clinical indication clearly. The ordering provider’s note must state the specific symptom rather than only the test name. A note like “secondary amenorrhea x 6 months, prolactin ordered to rule out hyperprolactinemia” does the job. Vague notes (“labs ordered”) are the most common documentation failure in audits.
2. Link one covered ICD-10 code to the 84146 line item. Use the most specific code available. E22.1 (hyperprolactinemia) is the strongest linkage when the diagnosis is confirmed. Use a symptom code (e.g., N91.1 secondary amenorrhea) when the test is ordered to evaluate an unconfirmed condition.
3. Confirm place of service. POS 11 (office) applies when the practice performs the test in-house under a CLIA certificate. POS 81 (independent laboratory) or POS 22 (on-campus outpatient hospital) apply when the specimen is sent to a reference lab. A mismatched POS code triggers an automatic edit.
4. Identify the performing lab on the claim. If a reference lab performs the test, the reference lab bills 84146 using its own NPI. The ordering practice may bill a separate specimen collection code (e.g., 36415 for venipuncture) but not 84146 itself.
5. Apply modifier -91 only with caution. Modifier -91 (repeat clinical diagnostic laboratory test) may fit when a second prolactin assay is medically necessary on the same date of service. One example is confirming an elevated result before starting treatment. Payer rules on this vary, so check your payer’s modifier policy before appending it, because incorrect use generates denials.
6. Issue an ABN when medical necessity is uncertain for Medicare patients. If the ordered prolactin test doesn’t link to a Medicare-covered ICD-10 code, issue an Advance Beneficiary Notice of Non-Coverage before the test. Without a valid ABN, the practice cannot bill the patient if Medicare denies the claim.

Steps 3 and 4 come down to one question: Who performs the assay? The flow below starts with the coverage check from step 6, then maps each answer to the right billing entity and place of service.

Codes commonly confused with CPT 84146

The prolactin CPT code is occasionally mis-selected when coders search by test name rather than by confirmed AMA descriptor. The following table distinguishes 84146 from adjacent chemistry codes that generate upcoding or undercoding errors.

Codes commonly billed alongside CPT 84146

Prolactin testing rarely appears alone on a claim. Endocrine and reproductive evaluations routinely include several chemistry codes ordered together. The AAPC CPT code reference and the NCCI Policy Manual treat the codes below as separately payable alongside 84146. Each test needs its own indication and documentation.

No NCCI edits pair these codes as mutually exclusive when each has an independent clinical indication. Document each test’s rationale separately in the ordering note to support multiple chemistry codes on the same claim. For TSH on the same claim, our guide to CPT 84443 covers its ICD-10 linkage and rates.

Top reasons CPT 84146 claims are denied

Most 84146 denials fall into five categories, and each is preventable with the right front-end workflow. Clear denial management workflows cut the rework when one does slip through. These are the patterns billing teams see most often:

• Missing or non-covered ICD-10 linkage. The claim lists a diagnosis not on the payer’s LCD for prolactin testing. Fix: Cross-reference the covered-code list before submission. Medi-Cal’s updated policy is one example where older covered-code lists no longer match current requirements.
• Frequency limit exceeded. The payer has already paid for a prolactin assay within the allowed interval (commonly 12 months for monitoring, though this varies). Fix: Query the payer’s claims history or run an eligibility check that returns benefit utilization data before ordering a repeat test.
• Missing Advance Beneficiary Notice (ABN) for Medicare patients. Prolactin is ordered with an uncovered ICD-10 code and no ABN, so the practice cannot shift liability to the patient. Fix: Add an ABN step whenever a lab order has no covered diagnosis linked.
• Incorrect place of service. The practice bills POS 11 (office) but sends specimens to a reference lab that bills under a separate NPI. Fix: Settle billing responsibility in the lab service agreement. Practices that send specimens to a reference lab should bill only the collection code.
• Ordering provider not enrolled. The provider who ordered the test is not enrolled with the payer billed. Fix: Audit provider enrollment lists quarterly, because a newly hired provider often orders tests before their payer enrollment is complete.

How Pabau supports CPT 84146 billing

Billing CPT 84146 runs from order entry to ERA posting, and an error at any step costs time and revenue. Purpose-built claims management software keeps those steps in one system, so billers aren’t catching every error by hand.

Without that connection, a practice checks coverage by phone, keys claims into a payer portal and matches paper EOBs to each test. In Pabau, eligibility checks run through Claim.MD before the visit, so a coverage problem shows up before the prolactin test is ordered.

Claims then go out electronically, and claim status stays visible until the payer responds. When the electronic remittance advice comes back, our guide to electronic remittance advice explains how to read it and post it.

Endocrinology, reproductive health and functional medicine practices often bill FSH, LH, estradiol and TSH on the same date as 84146. Keeping those orders, diagnosis links and claims in one system lets your billing team review each line in one place before submission.

Send cleaner prolactin claims the first time

Pabau checks eligibility through Claim.MD before the visit, sends lab claims electronically and tracks their status, so your billing team spends less time on rework.

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Conclusion

CPT 84146 is a simple code to choose and an easy one to lose money on. The protection happens before the specimen leaves the room. Confirm the diagnosis is covered under your MAC’s LCD, check the payer’s frequency limit and settle who bills the assay.

Practices that build those checks into ordering stop treating 84146 denials as a billing problem. The trade-off is a minute more at order entry, which costs far less than reworking a denied claim weeks later.

Book a demo to see how Pabau handles eligibility checks, electronic claims and claim tracking for your lab orders.

Continue your research

Want to know what a clearinghouse does before a claim reaches the payer? Pabau’s Claim.MD clearinghouse guide walks through electronic claims, eligibility checks and claim status tracking.

Need to understand denial reason codes on your ERAs? Denial codes in medical billing covers CARC and RARC codes so your team can act on remittance data faster.

Ordering progesterone in the same fertility workup? CPT code 84144 covers progesterone billing, ICD-10 linkage and the current rate.

Running a gonadal axis panel alongside prolactin? CPT code 83002 covers luteinizing hormone billing and the codes it pairs with.

Billing for other reproductive lab codes? IVF CPT codes reference covers the reproductive medicine code set that often appears on the same claim date as 84146.

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