CPT 84443: Thyroid Stimulating Hormone (TSH)
CPT 84443 reports a thyroid stimulating hormone (TSH) blood test, the first-line measure for evaluating thyroid function. It is a clinical laboratory service priced under the Medicare Clinical Laboratory Fee Schedule (CLFS), not the Physician Fee Schedule, so it carries no PFS dollar amount.
- Code type
- Clinical laboratory test (chemistry/endocrine)
- Priced under
- Medicare Clinical Laboratory Fee Schedule (CLFS), not the PFS
- Components
- Single analyte (TSH)
- Frequency notes
- Medicare covers diagnostic use only; not preventive screening
What is CPT 84443 used for?
CPT 84443 reports a thyroid stimulating hormone (TSH) blood test, the first-line lab for evaluating thyroid function. An abnormal TSH prompts reflex testing of thyroid hormone levels. It is used to diagnose and monitor hypothyroidism and hyperthyroidism and to titrate thyroid replacement therapy.
Because TSH is a diagnostic test, payer coverage hinges on the ordering indication and testing frequency rather than on a preventive schedule.
How much does Medicare pay for 84443?
On the Physician Fee Schedule, 84443 shows status indicator X — statutory exclusion, so no RVUs and no PFS dollar. That is correct: lab tests are not paid on the PFS.
Payment comes from the Medicare Clinical Laboratory Fee Schedule (CLFS), priced with national limitation amounts and gapfill/crosswalk methodology. The Medicare fee calculator PFS lookup returns nothing — reference the current CLFS rate from your MAC or payer fee file.
Does Medicare cover TSH for screening?
No — this is the key TSH coverage rule. Medicare covers 84443 only for diagnostic use, tied to signs, symptoms, or an established thyroid condition. It does not cover TSH as routine preventive screening.
- Symptomatic or established thyroid disease → covered with a supporting diagnosis.
- Routine screening of an asymptomatic patient → not covered by Medicare.
- Some commercial payers cover preventive TSH; modifier 33 may apply when the plan covers screening.
Coverage detail lives in the thyroid-testing NCD/LCD, which lists the covered ICD-10 codes.
How do frequency and ABN rules apply?
Example: a stable hypothyroid patient on a steady levothyroxine dose is tested a third time in one year without a documented reason. Because stable patients are generally limited to about twice yearly, that extra test may deny for frequency. Document dose changes or new symptoms to support additional testing.
When the indication is not covered or frequency is exceeded, obtain an ABN so the patient accepts financial responsibility, and link every order to a supporting diagnosis for payer medical-necessity. Related endocrine monitoring includes 83036.
Frequently asked questions
Because 84443 is a clinical laboratory test, not a physician service. On the PFS it carries status indicator X (statutory exclusion) and is never paid there. Payment comes from the Clinical Laboratory Fee Schedule (CLFS) using national limitation amounts and gapfill/crosswalk pricing. The PFS $0 is expected, not an error.
No. Medicare does not cover TSH (84443) as a preventive screening test. It is covered only when ordered to diagnose or follow up a thyroid disorder, supported by an appropriate diagnosis. Ordering it as a routine screen risks a non-coverage denial, so an ABN may be appropriate.
For a clinically stable patient, thyroid testing is generally not covered more than about twice a year. More frequent testing is payable when it is reasonable and medically necessary — for example, during dose titration — and the record documents that need.
Sources & further reading
Reviewed by the ImmediCare Solutions RCM team
Certified billers and coders handling claims across 50+ specialties nationwide. This entry is reviewed against current payer policy and CMS rules. Last review: Jul 5, 2026.
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