ModifiedMedical Mutual - OhioPolicy AHS - G2045 - Thyroid Disease Testing

Thyroid Disease Testing

Medical Mutual - Ohio coverage policy governing laboratory testing for diagnosis, monitoring, and surveillance of thyroid disease for covered individuals; defines which thyroid tests meet or do not meet coverage criteria and monitoring intervals.

Policy Summary

PayerMedical Mutual - Ohio

PolicyThyroid Disease Testing

Policy CodePolicy AHS - G2045 - Thyroid Disease Testing

Change TypeCriteria revised and additions (03/05/2025)

Effective DateMar 19, 2015

Next Review Date

Key ActionVerify member benefits and document clinical justification (signs/symptoms, pregnancy status, medication exposure, thyroid nodule, or history of pregnancy loss) when ordering thyroid testing.

SourceLink

POLICY UPDATE CHANGES

Removed 'are undergoing evaluation for infertility' from CC1.d and updated CC1.d to require TSH testing for individuals capable of becoming pregnant who have experienced two or more pregnancy losses.

Added CC1.e: 'TSH testing for individuals with a thyroid nodule.'

Reformatted CC4 and specified thyroid antibodies (Tg-Ab, TPOAb, TRAB, TSI) with coverage: testing once every three years meets coverage criteria for individuals with hypothyroidism or hyperthyroidism.

Updated background, guidelines, and evidence-based scientific references.

multipleCovered scenarios

listedNot covered tests

03/05/2025Last review

Trek Health ingests and normalizes Transparency in Coverage data and payer policy updates to give provider organizations a clear view of how commercial reimbursement behaves across markets, payers, and services. Our platform transforms raw payer disclosures into structured intelligence that supports contract evaluation, payer negotiations, and service line strategy. By combining market benchmarks with ongoing policy visibility, Trek helps teams identify variability, risk, and opportunity in commercial reimbursement. The result is faster insight, stronger negotiating positions, and more informed financial decisions.

>=2015Policy effective since

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Coverage Criteria — When Testing Is Covered

Covered indications

Covered when the following scenario-specific criteria are met:

Initial diagnostic testing for suspected thyroid dysfunction: TSH testing to confirm or rule out primary hypothyroidism or overt hyperthyroidism; when abnormal, reflex or follow-up fT4 (and fT3/TT3 for hyperthyroidism) as indicated.

See Notes 1 and 2 for symptom lists and diagnostic guidance

Monitoring treated hypothyroidism: For primary hypothyroidism: TSH and fT4 every 6 weeks after a dosage change until stable; annually in stable individuals; for long-term levothyroxine (>18 months) monitoring may occur at 6-month intervals then annually. For secondary hypothyroidism monitor with fT4 every 6 weeks after dosage change and annually when stable.

Monitoring treated hyperthyroidism: Repeat TSH and fT4 every 8 weeks while treating; patients starting antithyroid drugs monitored with serum fT4 and TT3 approximately 2-6 weeks after initiation depending on severity; once euthyroid on minimal dose evaluate at 2-3 month intervals; long-term ATD (>18 months) interval may be extended to 6 months; after radioactive iodine begin follow-up at 1-2 months then every 4-6 weeks for 6 months or until stabilization; annual monitoring after first year.

Screening/monitoring related to exposures or conditions: Annual TSH testing for asymptomatic individuals prescribed drugs that interfere with thyroid function; amiodarone: within first 3 months then every 3-6 months; interferon-alpha, interleukin-2, tyrosine kinase inhibitors, lithium: every 6 months; medications affecting thyroid metabolism (eg, phenobarbital, phenytoin, carbamazepine): annually; test when dosage changes or symptoms develop.

Pregnancy/postpartum: For pregnant or postpartum individuals with symptoms of thyroid dysfunction, TSH and fT4 testing once every 4 weeks meets coverage; in pregnant individuals diagnosed with hyperthyroidism, TT4, Tg-Ab, TRAb, and TPOAb meet coverage.

Use trimester-specific reference ranges for assays; fT4 preferred, TT4 may be useful when fT4 ranges unavailable or discordant.

High-risk or targeted one-time screening: One-time TSH screening for asymptomatic individuals at high risk (personal/family history of thyroid dysfunction; personal/family history of type 1 diabetes or other autoimmune disease), individuals with thyroid or other endocrine neoplasm, chronic/acute urticaria, pediatric short stature or failure-to-thrive; TSH testing for individuals with a thyroid nodule; TSH every 3 months with reflex fT4/fT3 when abnormal for individuals undergoing immune reconstitution therapy (eg, alemtuzumab, HAART, post-BMT/HSCT).

Thyroid cancer surveillance: For individuals with thyroid cancer, testing for serum thyroglobulin and/or Tg-Ab for detection of recurrence, post-surgical evaluation, surveillance, and maintenance for differentiated thyroid carcinomas meets coverage.

Not medically necessary / Not covered

Tests not meeting coverage criteria:

Specific not-covered assays: TRH or TBG testing for evaluation of cause of hyper- or hypothyroidism; reverse T3, T3 uptake, and TT4 for other situations; measurement of TT3 and/or fT3 for assessment of hypothyroidism; measurement of total or fT3 to assess levothyroxine dose; screening of asymptomatic nonpregnant individuals during a general exam without abnormal findings.

These uses do not meet coverage criteria.

Clinical criteria and testing pathways

Covered when testing is indicated per specialty guidelines (examples below):

Pregnancy — indicated testing: When testing is clinically indicated in pregnancy (eg, symptoms, history of thyroid disease, type 1 diabetes, recurrent miscarriage, significant goiter/nodules), measure TSH as first-line; apply trimester-specific reference ranges and monitor TSH every 4-6 weeks when adjusting levothyroxine dose.TSH targets in pregnancy: trimester-specific (1st 0.1-2.5 mIU/L; 2nd 0.2-3.0 mIU/L; 3rd 0.3-3.0 mIU/L)

Use total T4 or method-appropriate fT4 measurement if trimester-specific fT4 reference ranges are unavailable.

Autoimmune evaluation: Consider measurement of TPOAb when evaluating patients with subclinical hypothyroidism or recurrent miscarriage; consider TSHRAb in pregnant patients with prior Graves' disease treated by RAI or surgery (test at ~20-26 weeks and earlier as indicated).

TPOAb measurement should be considered in evaluation of recurrent miscarriage regardless of fertility status.

Monitoring patients on therapy: For patients treated for hypothyroidism, monitor TSH and adjust levothyroxine to keep TSH between the lower limit of the reference range and 2.5 mIU/L in pregnancy; TSH measured every 4-6 weeks while adjusting.

Clinical coverage criteria and monitoring

Coverage-aligned recommendations from professional societies (conditions warranting testing and monitoring)

Initial screening: Serum TSH is the first-line screening test for suspected thyroid dysfunction; obtain fT4 to confirm diagnosis or when TSH may be unreliable (eg, central hypothyroidism, pregnancy).

ATA, AACE, ASCP, and Endocrine Society guidance support this approach.

Indications for TSH testing: Test TSH in patients with symptoms/signs (eg weight change, fatigue, goiter, cardiac arrhythmia), specific conditions (adrenal insufficiency, type 1 diabetes, infertility, alopecia, vitiligo), and in high-risk pregnant women.

List of conditions and risk factors provided by ATA/AACE and ATA pregnancy guidance.

Pregnancy monitoring: Use trimester-specific TSH reference ranges; monitor TSH every 4 weeks in women at risk or on therapy until mid-pregnancy and at least once near 30 weeks; measure fT4 or TT4 when TSH is suppressed or to clarify thyrotoxicosis.TSH ranges: 1st 0.1-2.5; 2nd 0.2-3.0; 3rd 0.3-3.0 mIU/L

Covered testing and monitoring criteria

Testing and monitoring algorithms (per NICE and ETA guidance) — follow the cascaded approach and specified monitoring intervals

Initial testing when secondary thyroid disease is NOT suspected: Measure TSH alone first; if TSH is above reference range, measure FT4 in the same sample; if TSH is below reference range, measure FT4 and FT3 in the same sample.

NICE 1.2.8 cascading algorithm.

Initial testing when secondary thyroid disease IS suspected or for children/young people: Measure both TSH and FT4 initially; if TSH is below reference range, measure FT3 in same sample.

NICE 1.2.9 recommended approach.

Central hypothyroidism diagnosis: Confirm central hypothyroidism by FT4 below the lower limit of normal and inappropriately low/normal TSH on at least two separate determinations after exclusion of listed conditions; combined FT4 and TSH determination is recommended.2 separate determinations

ETA CeH guideline.

Assisted reproduction

Assisted reproduction screening

Screening in subfertile women: ETA recommends routine screening for thyroid disorders in women of subfertile couples (subfertile defined as failure to achieve clinical pregnancy after 12+ months). Treatment with levothyroxine in cohorts with mainly TSH > 4.0 mIU/L was associated with increased live birth rates in meta-analysis.TSH > 4.0 mIU/L context

ETA assisted reproduction guidance.

Graves' disease

Graves' disease management and testing

Use of TSH-R-Ab: Measure TSH receptor-stimulating antibody (TSH-R-Ab) for diagnosis and management of Graves' disease, for pregnancy presentation, and prior to stopping antithyroid drug treatment; if maternal TSH-R-Ab remains >3x normal cutoff, monitor fetus throughout pregnancy.> 3x normal cutoff for fetal monitoring

ETA recommendations.

Pediatric Graves' management: Measure serum TSH receptor antibodies in all pediatric patients with hyperthyroidism; first-line prolonged methimazole/carbimazole for >=3 years with dose titration preferred; avoid propylthiouracil and avoid RAI in children <10 where possible, favoring surgery for large goiter.3 years minimum ATD

ETA pediatric guidance.

Mitochondrial disease screening

Mitochondrial disease context

Screening in mitochondrial disease: Consider annual assessment of TSH and FT4 (and other endocrine tests) in individuals with mitochondrial diseases; annual screening recommended for those with mtDNA deletions.annual

MMS recommendations.

Updated Coverage Criteria (selected changes)

Revisions to coverage criteria (CC) per 03/05/2025 update:

CC1.d revised: TSH testing for individuals capable of becoming pregnant who have experienced two or more pregnancy losses.

Replaced prior language that included 'are undergoing evaluation for infertility'

CC1.e added: TSH testing for individuals with a thyroid nodule.

New indication added

CC4 reformatted: For individuals with hypothyroidism or hyperthyroidism, testing once every three years for thyroid antibodies (Tg-Ab, TPOAb, TRAB, thyroid-stimulating immunoglobulins [TSI]) meets coverage criteria.every 3 years

Specifies antibody panel and frequency

Certain assays and uses are explicitly excluded from coverage. Specifically, testing for thyrotropin-releasing hormone (TRH) or thyroxine‑binding globulin (TBG) to evaluate causes of hyper- or hypothyroidism does not meet coverage criteria. Additionally, testing of reverse T3, T3 uptake, and total T4 (TT4) for situations not listed in the covered indications does not meet coverage criteria. Measurement of total T3 (TT3) and/or free T3 (fT3) for assessment of hypothyroidism, and use of total or free T3 to assess levothyroxine dosing, does not meet coverage criteria. Finally, screening for thyroid dysfunction during a routine general exam in asymptomatic, nonpregnant individuals without abnormal findings does not meet coverage criteria.

The USPSTF concludes that current evidence is insufficient to assess the balance of benefits and harms of screening for thyroid dysfunction in nonpregnant, asymptomatic adults and recommends against screening for thyroid cancer in asymptomatic adults.

Multiple specialty societies do not recommend routine universal screening of asymptomatic, nonpregnant individuals. The ATA/AACE recommend targeted TSH testing for patients with specific signs, symptoms, or risk conditions and advise against routine serum T3/fT3 testing to diagnose hypothyroidism. The ASCP recommends starting with TSH and avoiding multiple tests for initial evaluation and discourages TSH screening in annual well visits for asymptomatic adults. The Endocrine Society also advises against routine total or free T3 measurement to guide levothyroxine dosing and discourages routine thyroid ultrasound without palpable abnormalities.

The Society for Maternal-Fetal Medicine (SMFM) specifically recommends against screening asymptomatic pregnant individuals for subclinical hypothyroidism.

The March 5, 2025 revision removed the phrase 'are undergoing evaluation for infertility' from the prior version of CC1.d. The updated language requires TSH testing for individuals capable of becoming pregnant who have experienced two or more pregnancy losses, clarifying that infertility evaluation alone is not a covered reason under that clause.

Certain thyroid tests have limited clinical utility and are not supported for routine use. The policy specifies that reverse T3, T3 uptake, and routine use of TT4 for unspecified situations do not meet coverage criteria. The Endocrine Society and other guideline sources recommend avoiding routine measurement of total or free T3 to assess levothyroxine dose, and published analyses have concluded there is no reason to measure T3 routinely in patients on levothyroxine without specific indications.

Evidence does not support routine measurement of T3 in patients with hypothyroidism who are treated with levothyroxine. Studies and guideline recommendations indicate no demonstrated clinical utility for routine T3 testing to guide levothyroxine therapy, and the Endocrine Society recommends against using total or free T3 to evaluate LT4 dosing.

Routine universal screening of thyroid function in pregnancy and in asymptomatic women is not supported. Guidance from ATA/AACE, ASRM, and SMFM emphasizes targeted testing for pregnant individuals at increased risk or with signs or history of thyroid disease rather than universal screening of all asymptomatic women.

NICE guidance advises against testing for thyroid dysfunction when the only concern is type 2 diabetes or when the patient has an unrelated acute illness. For initial assessment when secondary thyroid disease is not suspected, NICE recommends a cascaded approach: consider measuring TSH alone and then reflexing to fT4 if TSH is above the reference range or to fT4 and fT3 if TSH is below the reference range.

Where the 03/05/2025 revisions adjusted coverage language but did not restate every prior exclusion or procedural detail, existing exclusions and not‑medically‑necessary statements from earlier sections remain applicable unless explicitly changed. Providers should rely on the policy's current covered indications and exclusions and include documentation supporting the specific indication when ordering tests.

Coding — Procedure Codes & Reference Ranges

Applicable CPT/HCPCS procedure codes (placeholder)mixed

No codes listed

Applicable CPT/HCPCS Procedure CodesCPT

80438	Thyrotropin-releasing hormone (TRH) stimulation panel; 1 hour
80439	Thyrotropin-releasing hormone (TRH) stimulation panel; 2 hour
83519	Immunoassay for analyte other than infectious agent antibody or infectious agent antigen; quantitative, by radioimmunoassay (eg, RIA)
83520	Immunoassay for analyte other than infectious agent antibody or infectious agent antigen; quantitative, not otherwise specified
84432	Thyroglobulin
84436	Thyroxine; total
84439	Thyroxine; free
84442	Thyroxine-binding globulin (TBG)
84443	Thyroid stimulating hormone (TSH)
84445	Thyroid stimulating immune globulins (TSI)

1–10 of 16

1/2

Referenced external resources (no codes)mixed

No codes listed

TSH laboratory normal range reference

Typical reference range (nonpregnant adults)Approximately 0.4–5.0 mU/L (most labs use an upper limit ~4.5–5.0 mU/L)

Clinical interpretationTSH is the most sensitive initial test; normal TSH usually obviates further testing

Use in initial workupIf TSH abnormal, follow-up with fT4 (and fT3/TT3 when hyperthyroidism suspected)

Age considerationsTSH tends to shift higher with increasing age; laboratory reference ranges may vary by age

Assay sensitivityModern chemiluminometric TSH assays detect to ~0.01 mU/L, enabling detection of subtle abnormalities

Provider Actions — Documentation, Prior Auth, and Utilization Notes

Documentation Required

Verify benefits and regulatory precedence

Verify member benefits and applicable government policies (Medicare/Medicaid) prior to testing — coverage decisions depend on individual benefits and Local/National Coverage Determinations.

Application depends on individual benefits at time of request
If conflict with government policy (LCD/NCD/state Medicaid), government policy prevails

Prior Authorization

Prior authorization — none specified

No prior authorization specified in this policy for routine thyroid testing. Verify payer-specific prior authorization rules separately.

Policy text does not list a prior authorization requirement for these tests
Check member benefit and payer portals for plan-specific requirements

Background — Clinical and Technical Context

Thyroid hormones play essential roles in growth, development, and metabolic regulation. Disorders include hypothyroidism, hyperthyroidism, goiter, thyroiditis, and thyroid tumors. Laboratory testing—primarily TSH with reflex or confirmatory free T4 (fT4) and selective free/total T3 (fT3/TT3)—is central to diagnosis, monitoring of therapy, and surveillance. Modern chemiluminometric TSH assays have detection limits around 0.01 mU/L, while T3 immunoassays may have variable agreement with reference methods and reverse T3 measurement has limited reliability; these analytical considerations inform appropriate test selection and interpretation.

Definitions & Key Terms

Key laboratory and clinical terms

TSHThyroid‑stimulating hormone — first‑line screening test for thyroid dysfunction

fT4 (FT4)Free thyroxine — used to confirm hypothyroidism or when TSH unreliable (eg, pregnancy, central disease)

fT3 (FT3) / TT3Free or total triiodothyronine — used selectively for suspected thyrotoxicosis; not routinely used to assess levothyroxine dose

TT4/TT3Total thyroxine/triidothyronine — may be useful in pregnancy if method‑specific fT4 ranges unavailable; requires pregnancy‑adjusted reference ranges

TPOAbThyroid peroxidase antibody — used in evaluation of subclinical hypothyroidism and recurrent miscarriage

Autoimmune thyroiditis — definition and common antibodies

Revision History & Policy Changes

2025-03-05material_revisionLatest

Reviewed and updated background, guidelines, and references; revised CC1.d to require TSH testing for individuals capable of becoming pregnant who have experienced two or more pregnancy losses (removing prior infertility-evaluation language).

2025-03-05addition

Added CC1.e establishing TSH testing for individuals with a thyroid nodule as a covered indication.

2025-03-05material_revision

Policy Summary

PayerMedical Mutual - Ohio

PolicyThyroid Disease Testing

Policy CodePolicy AHS - G2045 - Thyroid Disease Testing

Change TypeCriteria revised and additions (03/05/2025)

Effective DateMar 19, 2015

Next Review Date

SourceLink

On This Page

For hyperthyroid treatment in pregnancy monitor fT4 (and TT3 if T3 thyrotoxicosis) to keep free/total thyroid hormones at upper end of pregnancy-specific normal range.

Test selection considerations: Do not routinely test serum T3/fT3 to diagnose hypothyroidism; prefer fT4 over total T4 except in pregnancy where total T4 may be superior if fT4 reference ranges are unavailable; avoid relying on reverse T3 for diagnosis.

Be aware of assay limitations and potential biotin interference; repeat testing after biotin discontinuation if interference suspected.

ATA pregnancy recommendations.

Thyroid antibody testing: Consider TPOAb in subclinical hypothyroidism and recurrent miscarriage; measure TRAb in pregnant patients with prior Graves' disease (timing 20-26 weeks or earlier as recommended) and when determining cause of hyperthyroidism.

ATA/AACE guidance.

Postpartum thyroiditis surveillance: Women with postpartum depression should have TSH, fT4, and TPOAb testing; symptomatic hypothyroid phase retest TSH in 4-8 weeks or initiate treatment; women with prior PPT should have annual TSH testing.

ATA recommendations.

Monitoring frequency examples: Pregnancy: maternal FT4 and TSH every 2 weeks after therapy initiation then every 4 weeks after target achieved; post-RAI: fT3, fT4 and TSH every 6 weeks for first 6 months; patients on antithyroid drugs: TSH, FT4, FT3 every 6 weeks until TSH normalized then TSH every 3 months until drug stopped; after stopping ATD: TSH (with cascading) within 8 weeks then every 3 months for 1 year then annually.intervals as specified

ETA and NICE monitoring schedules.

Pregnancy trimester TSH reference ranges

First trimester0.1–2.5 mIU/L

Second trimester0.2–3.0 mIU/L

Third trimester0.3–3.0 mIU/L

Testing considerationsUse assay- and trimester-specific reference ranges; if fT4 assay ranges unavailable, total T4 with pregnancy-adjusted range or FT4 index may be used

High‑risk features prompting early TSH testing in pregnancy

Age >30 yearsConsider early TSH testing in pregnancy for individuals older than 30 years

History of thyroid dysfunction or prior thyroid surgeryPrior thyroid disease warrants early evaluation

Goiter or thyroid nodulePalpable thyroid enlargement or nodule prompts early testing

TPOAb positivity or other autoimmune disease (eg, type 1 diabetes)Autoimmune disease or positive TPOAb increases risk and supports early testing

History of miscarriage/preterm delivery, infertility, head/neck radiation, or residence in iodine‑deficient areaPrior pregnancy loss, infertility, prior radiation, or iodine deficiency are high‑risk features for early screening

Billing Rule

Initial testing expectations

Start evaluation with TSH; confirm abnormal findings with free T4 rather than ordering multiple tests initially. Avoid ordering TT3/fT3 or other non-recommended tests for initial hypothyroidism assessment.

Initial test: TSH alone recommended when secondary thyroid disease is not suspected
If TSH abnormal, reflex to fT4 (and fT3/TT3 when TSH low per guidance)
Do not order TT3/fT3 or reverse T3 for initial assessment of hypothyroidism

Step Therapy

Stepwise testing in pregnancy and monitoring

For pregnancy: use a stepwise approach — measure TSH first with trimester-specific and method-specific reference ranges; reflex to fT4, TT3, and TRAb selectively per clinical context. Monitor treated pregnant individuals every ~4 weeks while adjusting therapy and then per guideline intervals.

Apply trimester-specific TSH reference ranges (eg, ATA first trimester 0.1–2.5 mIU/L, etc.) and method-specific fT4 ranges
If first-trimester TSH low (<0.1), obtain history/physical and measure fT4; consider TT3 and TRAb if clinically indicated
For pregnant individuals on therapy: monitor TSH (and fT4 for hyperthyroidism) approximately every 4 weeks while adjusting dose; consider more frequent monitoring (every 2 weeks) early after initiation in some guidance

Documentation Required

Thyroid antibody testing frequency and pregnancy indications

Thyroid antibody testing: covered once every three years for individuals with hypothyroidism or hyperthyroidism. For pregnancy and specific clinical scenarios (e.g., Graves' disease), TRAb/TPOAb/Tg‑Ab testing may be indicated more frequently per guidelines.

Covered once every 3 years: Tg‑Ab, TPOAb, TRAb, TSI for individuals with hypo- or hyperthyroidism
In pregnancy or suspected Graves' disease, TRAb testing recommended at specific gestational windows (eg, initial, 18–22 weeks, and late pregnancy if elevated)

Documentation Required

Required clinical justification and documentation expectations

Required clinical justification and documentation must accompany testing requests: document signs/symptoms, indication (pregnancy/postpartum, medication exposure, thyroid nodule, prior losses), treatment status, trimester (if pregnant), and timing of prior tests to support frequency of repeat testing.

Document clinical signs/symptoms prompting testing (eg, fatigue, weight change, neck mass, arrhythmia)
If pregnancy-related: record trimester and use trimester- and method-specific reference ranges; document prior pregnancy losses when relevant
If monitoring therapy: document medication, dose change date, and planned follow-up interval (eg, 6 weeks after dose change for hypothyroid patients)
For antibody testing frequency: document prior antibody test dates to justify 3‑year interval

Note

Clinical management and monitoring guidance (informational)

Clinical management notes (guidance-only): monitoring intervals and tests are recommendations to support care — they are not prescriptive step-therapy mandates. Use clinical judgment and specialty guidance (ACOG, ATA, NICE, ETA) when individualizing monitoring.

Hypothyroidism on treatment: TSH and fT4 every 6 weeks after dose change, then annually when stable; alternatives per age and guideline-specific schedules
Hyperthyroidism: monitor TSH and fT4 every ~8 weeks; more frequent (2–6 weeks) after initiating antithyroid drugs depending on severity; post‑RAI follow-up every 4–6 weeks for 6 months or until stabilization
Medication-related monitoring: tailored intervals for amiodarone, interferon, TKIs, lithium, and other agents as listed in policy

Denial Risk

Denial risk for non-covered tests

Tests that do NOT meet coverage criteria or are inconsisten with updated coverage should trigger denial risk unless exceptional documentation is provided. Examples include TRH, TBG, reverse T3, T3 uptake, TT4 for non‑listed indications, and TT3/fT3 for assessment of hypothyroidism or levothyroxine dosing.

Not covered: TRH, TBG, reverse T3, T3 uptake, TT4 in non‑listed situations
Not covered for hypothyroidism assessment or levothyroxine dose decisions: TT3 and/or fT3

Billing Rule

Referenced CPT/HCPCS codes (billing reference)

Referenced CPT/HCPCS procedure codes are provided for billing reference. Verify code applicability against service performed and payer billing rules.

Common codes: 84443 (TSH), 84439 (free T4), 84481 (free T3), 84480 (TT3), 86376 (microsomal antibodies), 86800 (thyroglobulin antibody), 84432 (thyroglobulin), 84445 (TSI)
Panels and specialized codes: 80438/80439 (TRH stimulation panels) — these panels include multiple TSH measurements as specified

DefinitionAutoimmune thyroiditis: group of disorders (eg, Hashimoto's, painless, postpartum thyroiditis) with antibodies to thyroid antigens commonly leading to hypothyroidism or transient thyrotoxicosis.

Common antibodiesAntithyroglobulin (Tg-Ab) and antithyroid peroxidase (TPOAb) are frequently elevated, often together in Hashimoto's

Clinical courseHashimoto's often leads to permanent hypothyroidism; painless and postpartum thyroiditis may have transient thyrotoxic followed by hypothyroid phases

Analytical validity (TSH/T4/T3 assays)

TSH assay performanceModern chemiluminometric TSH assays have detection limits ~0.01 mU/L, with high sensitivity

T4/T3 assay variabilityAutomated chemiluminometric assays measure total T4/T3; immunoassays for T3 may disagree with LC/MS/MS and show method‑dependent variability

Reverse T3 reliabilityReverse T3 measurement has limited reliability and cannot reliably distinguish hypothyroidism from euthyroidism

TPOAb — role in evaluation and recurrence risk

Role in evaluationTPOAb (antithyroid peroxidase antibody) should be considered when evaluating subclinical hypothyroidism and recurrent miscarriage

Association with outcomesTPOAb positivity is associated with higher risk of adverse pregnancy outcomes and may guide monitoring

Testing frequency per policyFor individuals with hypo‑ or hyperthyroidism, antibody testing (including TPOAb) is covered once every three years when indicated

TRAb / TSHRAb / TSH‑R‑Ab — role in pregnancy and Graves' disease

Obstetric roleTSH‑receptor antibodies (TRAb/TSH‑R‑Ab) are recommended in pregnant patients with prior Graves' disease to assess fetal risk and guide monitoring

Diagnostic useTRAb measurement aids diagnosis and differentiation of Graves' hyperthyroidism from other causes

Monitoring guidanceIf maternal TRAb remains >3× the normal cutoff, fetal monitoring for thyroid dysfunction is advised

Subfertile — definition (assisted reproduction context)

DefinitionSubfertile: failure to achieve a clinical pregnancy after 12 months or more of regular unprotected sexual intercourse.

Screening recommendationETA recommends routine thyroid disorder screening in women of subfertile couples

Clinical implicationSevere thyroid dysfunction can contribute to menstrual disorders and subfertility; treatment of elevated TSH (>4.0 mIU/L in several studies) improved live birth rates

TSH‑R‑Ab (TRAb) — diagnostic and pregnancy risk use

Diagnostic useTSH‑R‑Ab (TRAb) is used to diagnose and manage Graves' disease and to predict fetal risk in pregnancy

Timing in pregnancyIn pregnant patients with prior Graves' disease obtain TRAb around 20–26 weeks (or earlier if indicated); repeat if initially elevated

Pediatric useMeasure serum TSH receptor antibodies in pediatric patients with hyperthyroidism for diagnosis and management

Central hypothyroidism (CeH) — definition and diagnostic clue

DefinitionCentral hypothyroidism (CeH): hypothyroidism due to hypothalamic‑pituitary dysfunction characterized by low FT4 with low or inappropriately normal TSH.

Diagnostic clueConfirm CeH by FT4 below reference range with low/normal TSH on at least two determinations; measure both FT4 and TSH when suspected

MonitoringIn hypothalamic‑pituitary disease monitor FT4 and TSH at least biannually in childhood and annually thereafter; consider >20% FT4 decline as significant

Specific thyroid autoantibodies specified for coverage

Antibodies specified for coverageThyroglobulin antibody (Tg‑Ab), thyroid peroxidase antibody (TPOAb), TSH receptor antibody (TRAb), and thyroid‑stimulating immunoglobulins (TSI)

Coverage frequencyPolicy specifies antibody testing once every three years for individuals with hypothyroidism or hyperthyroidism

Use casesThese antibodies are used for autoimmune evaluation, recurrence risk assessment, pregnancy management, and thyroid cancer surveillance where applicable

Reformatted CC4 to specify thyroid antibody panel (Tg-Ab, TPOAb, TRAB, TSI) and added coverage interval: testing once every three years meets coverage criteria for individuals with hypothyroidism or hyperthyroidism.