Ensure services meet authorization/medical necessity and frequency limits

Services must meet authorization and medical necessity guidelines; measurement of TSH is covered only in the specified clinical situations and at the frequencies listed (e.g., no more than one TSH every 6 weeks for symptomatic patients or suspected secondary hypothyroidism; once every 3 months for patients on immune reconstitution therapy or on medications that can cause thyrotoxicosis; and specified annual and other interval-based monitoring situations). Providers must follow these limits when requesting authorization or submitting claims.

• Do not exceed the stated frequencies for covered TSH testing (e.g., one test every 6 weeks where indicated).
• Use TSH coverage rules when determining medical necessity for authorization and claims.

Order TSH as the first-line test; avoid reflexive multi-test panels

Order TSH as the first-line test when evaluating suspected thyroid dysfunction; avoid ordering multiple free hormone tests reflexively without clinical indication and confirm diagnoses with free T4 per guideline recommendations.

• Start with TSH for adults when secondary thyroid dysfunction is not suspected; measure FT4 only if TSH is abnormal (NICE/ASCP guidance).
• Consider measuring both TSH and FT4 initially for children or when secondary dysfunction is suspected.

Prior authorization: none specified in this policy

No explicit prior authorization requirements are stated in this policy section.

• Procedure codes listed are provided as reference for claims and authorization requests, but the policy does not specify required prior authorization.
• Follow payer-specific authorization processes if applicable to the member's benefit plan.

Start with TSH and cascade additional tests as indicated

Begin diagnostic evaluation with TSH and cascade testing based on results: if TSH is above the reference range obtain FT4; if TSH is below the reference range obtain FT4 and FT3/TT3 as indicated.

• If secondary thyroid dysfunction is suspected or in children, consider measuring both TSH and FT4 initially.
• Use the same sample for reflex/cascade testing where indicated (NICE guidance).

Reference CPT/HCPCS codes on authorization and claims

When requesting authorization or submitting claims, reference the CPT/HCPCS procedure codes listed in the policy for thyroid testing (including codes for TSH, free T4, total T4, T3 variants, thyroglobulin, and antibody tests).

• Referenced codes include (examples): 84443 (TSH), 84439 (free thyroxine), 84436 (total T4), 84480/84481 (T3 total/free), 84432 (thyroglobulin), 86800 (Tg antibody), 86376 (microsomal/TPO antibody).
• Procedure codes in the policy are a general reference and may not be all-inclusive.

Reflex testing: abnormal TSH → fT4; low TSH → fT4 + fT3/TT3

Reflex testing is required when TSH is abnormal: follow-up with free T4 for abnormal TSH; when TSH is low, confirm hyperthyroidism with free T3 and/or total T3 (or TT3) and follow the IRT-specific reflex rules when applicable.

• Abnormal TSH → obtain fT4 in the same sample when possible.
• Low TSH → obtain fT4 and fT3 or TT3 to confirm hyperthyroidism.
• For individuals undergoing immune reconstitution therapy, measure fT4 and fT3 per policy.

Monitor therapy in pregnancy: frequent TSH checks (every 4–6 weeks while adjusting)

In pregnant patients being treated for hypothyroidism, titrate levothyroxine with frequent TSH monitoring—measure TSH every 4–6 weeks while adjusting doses to target pregnancy-appropriate TSH levels.

• Use trimester-specific reference ranges for TSH and fT4 when available; if fT4 is discordant and trimester-specific fT4 ranges are unavailable, consider total T4.
• Target pregnancy-appropriate TSH (lower limit to 2.5 mU/L as noted in policy guidance).

Stepwise testing: start with TSH, confirm with free T4 before broader testing

Begin initial laboratory evaluation with TSH and confirm suspected diagnoses with free T4 before ordering additional thyroid tests; avoid ordering multiple concurrent thyroid tests for initial evaluation.

• ASCP and NICE recommend starting with TSH and using FT4 for confirmation rather than broad panels.
• Reserve additional tests (fT3/TT3, antibodies) for when clinically indicated by TSH result or specific scenarios.

Diagnostic approach: order TSH before concurrent multi-test panels

Begin diagnostic evaluation with TSH prior to ordering multiple concurrent thyroid tests; use reflex/cascade testing logic per guidelines to limit unnecessary multi-test panels.

• Avoid routine multi-test initial panels in asymptomatic adults; target testing to clinical indication.
• If TSH is abnormal, proceed with the appropriate reflex tests rather than preordering all tests.

Submit accurate documentation; use labs with trimester-specific reference ranges

Providers must submit accurate documentation for services performed. For thyroid testing in pregnancy, laboratories used should have trimester-specific reference ranges for their assays when measuring hormone levels.

• Document the trimester when testing pregnant or postpartum individuals and apply trimester-specific TSH and fT4 reference ranges when available.
• Ensure labs performing tests (including any LDTs) comply with CLIA validation requirements; LDTs are not FDA-approved but must be validated by the laboratory.

Pregnancy testing documentation: record trimester and use trimester-specific ranges

When testing thyroid function in pregnancy, document the patient’s trimester and use trimester-specific reference ranges for TSH and fT4 when available; if fT4 is discordant with TSH and trimester-specific fT4 ranges are unavailable, consider measuring total T4.

• Record trimester on the lab request/medical record to support appropriate interpretation.
• Prefer fT4 in pregnancy when trimester-specific ranges exist; otherwise use total T4 if discordant.

Thyroid cancer follow-up documentation: document Tg assay and TgAb

When measuring serum thyroglobulin (Tg) for thyroid cancer surveillance, document the assay type and concurrent Tg antibody (TgAb) measurement; postoperative Tg should be measured 6–12 weeks after total thyroidectomy and documented.

• Use the same assay for serial Tg/TgAb measurements and document assay calibration (e.g., BCR457 standard) when available.
• Document timing of postoperative Tg (6–12 weeks post-total thyroidectomy) to support surveillance claims.

Cascading test documentation: document paired reflex testing in same sample

If TSH is above the reference range, document that FT4 was obtained in the same sample; if TSH is below the reference range, document that FT4 and FT3 were obtained in the same sample. For children or when secondary dysfunction is suspected, document combined TSH and FT4 testing.

• Document sample timing and tests performed to support reflex/cascade testing rationale.
• For central hypothyroidism suspicion, document repeated combined FT4 and TSH determinations as required.

LDT validation and regulation: ensure CLIA validation is documented

Laboratory-developed tests (LDTs) must be validated and comply with CLIA as high-complexity tests; providers should note that LDTs are not FDA-approved/cleared but require laboratory validation and CLIA compliance when documenting testing methods.

• If using an LDT, document that the performing laboratory follows CLIA high-complexity validation procedures.
• Be aware that FDA clearance/approval is not required for clinical use of LDTs but documentation of laboratory validation is expected.

Denial risk: follow coding rules; TBG/TRH/reverse T3/T3 uptake not covered

Claims may be denied or payment recouped if coding and billing guidelines or current reimbursement policies are not followed; testing for TBG, TRH, reverse T3, and T3 uptake does not meet criteria and may be noncovered.

• Do not bill for TBG (84442), TRH panels (80438/80439 where not indicated), reverse T3 (84482), or T3 uptake (84479) in situations that the policy defines as not meeting criteria.
• Ensure coding follows industry standards and the policy's referenced CPT/HCPCS codes to avoid denials or recoupment.

USPSTF stance: do not perform routine screening in asymptomatic nonpregnant adults

The USPSTF finds current evidence insufficient to assess benefits and harms of screening for thyroid dysfunction in nonpregnant, asymptomatic adults; routine, asymptomatic population screening may therefore be discouraged and potentially denied.

• Target TSH testing to patients with risk factors or signs/symptoms rather than routine well-visit screening in asymptomatic adults.
• Document clinical indication when ordering TSH for screening-like circumstances to support medical necessity.

Risk of non-reimbursed routine TSH screening: target testing to indications

Ordering broad or multiple initial thyroid tests at routine well visits for asymptomatic adults is discouraged; targeted TSH testing based on risk or signs of dysfunction is recommended to avoid non-reimbursed testing.

• Start with TSH and proceed to reflex testing if abnormal rather than preordering broad multi-test panels for asymptomatic patients.
• Document clinical signs, symptoms, or risk factors when ordering tests to support coverage.

Avoid multiple initial tests: start with TSH and confirm with fT4

Avoid ordering multiple tests for an initial thyroid evaluation when starting with TSH; ASCP and other societies recommend beginning with TSH and confirming with free T4 as needed to reduce inappropriate multi-test ordering.

• If TSH is normal and there is no clinical indication, additional thyroid hormone testing is generally not supported.
• Document rationale if ordering multiple tests at baseline (e.g., suspicion of central hypothyroidism, pediatric evaluation).

Conflict with government policies: follow applicable LCDs/NCDs/state rules

If this policy conflicts with applicable government policies (e.g., Medicare LCDs/NCDs or state Medicaid rules), the government policy will govern coverage determinations; follow those policies where applicable.

• Check and apply relevant LCD/NCD or state Medicaid coverage rules for the member when they differ from this policy.
• Document any government-mandated coverage basis used to support testing requests.