Summary & Overview

CPT 84443: Thyroid‑Stimulating Hormone (TSH) Assay

CPT code 84443 denotes a quantitative laboratory assay for thyroid‑stimulating hormone (TSH), a key diagnostic test for evaluating thyroid function. Nationally, TSH measurement is a common and clinically important lab service used in primary care, endocrinology, and hospital outpatient settings to detect hypothyroidism, hyperthyroidism, and to monitor thyroid therapy. The code supports billing for routine venous blood collection and laboratory analysis performed by clinical medical laboratories.

This publication covers coverage and billing considerations for major national payers, including Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise explanation of the test purpose, typical clinical contexts, common encounter sites, and related laboratory panels. The report also outlines which ICD‑10 diagnosis categories are commonly associated with TSH testing and lists related laboratory CPT codes for bundled or complementary testing.

Intended for revenue cycle managers, laboratory directors, and clinicians, the piece provides benchmark context and policy-relevant details that inform coding decisions and claims submission. Data not available in the input is explicitly noted where applicable.

AetnaBlue Cross Blue ShieldCigna HealthUnitedHealthcareMedicare84443CPTlaboratoryTSHthyroid-functionclinical-laboratoryphlebotomyendocrinology

Billing Code Overview

CPT code 84443 describes a laboratory test that measures thyroid‑stimulating hormone (TSH) in a patient's blood. The analysis quantifies the concentration of TSH, a pituitary hormone that regulates thyroid function, to assist clinicians in evaluating thyroid status.

Service type: Clinical laboratory testing

Typical site of service: Clinical laboratory or outpatient phlebotomy collection

Clinical & Coding Specifications

Clinical Context

A 58-year-old patient with long-standing E11.10 Type 2 diabetes mellitus presents to a primary care clinic for routine follow-up and medication management. The clinician documents fatigue, weight gain, and cold intolerance and orders laboratory evaluation to assess thyroid function. A phlebotomy technician collects a venous blood specimen during the office visit. The specimen is sent to the clinical medical laboratory for quantitative measurement of thyroid–stimulating hormone using 84443. Results return to the family medicine or internal medicine clinician and are reviewed to determine whether thyroid dysfunction may be contributing to the patient’s symptoms or affecting management of chronic conditions such as diabetes or heart failure. Common workflow steps include order entry in the electronic health record, patient identification and venipuncture at the clinic or outpatient lab, specimen labeling and transport, laboratory analysis, and result reporting to the ordering provider for interpretation and documentation in the medical record.

Coding Specifications

Modifier	Description	When to Use
`26`	Professional component	Use when billing only the physician professional interpretation component, if applicable (rare for `84443`).
`90`	Reference (outside) laboratory	Use when the specimen is analyzed by an external reference laboratory and billed by the ordering facility.
`91`	Repeat clinical diagnostic laboratory test	Use when the same test is performed on the same day on the same patient to confirm an unexpected result.
`91` is used for repeated testing on the same specimen or same day confirmation.
`92` is not in the provided list so is not included.
`95`	Synchronous telemedicine service rendered via real-time interactive audio and video	Rarely relevant; use only when the ordering or result discussion occurs via telemedicine along with billing policies that allow the modifier.
`TC`	Technical component	Use when billing only the laboratory technical component if separated from a professional component (if applicable by payer).
`QW`	CLIA waived test	Use if the TSH assay used is CLIA-waived and the provider’s site meets CLIA-waived testing requirements.
`59`	Distinct procedural service	Use when another unrelated procedure or specimen handling requires separate reporting and bundling edits need to be overridden.
`90`	Duplicate entry avoided; already listed above
`91`	Duplicate entry avoided; already listed above

Taxonomy Code	Specialty	Notes
`291U00000X`	Clinical Medical Laboratory	Primary facility performing `84443` analysis and reporting results.
`207Q00000X`	Family Medicine Physician	Common ordering clinician for routine TSH testing during primary care visits.
`207R00000X`	Internal Medicine Physician	Common ordering clinician for chronic disease management and evaluation of symptoms requiring TSH measurement.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`E11.10`	Type 2 diabetes mellitus without complications	Diabetes patients often undergo TSH screening as part of routine chronic disease management and when symptoms suggest thyroid dysfunction.
`E11.11`	Type 2 diabetes mellitus with hypoglycemia without coma	Hypoglycemia symptoms can overlap with thyroid disease; TSH testing may be ordered in evaluation.
`I50.810`	Acute combined systolic and diastolic heart failure	Thyroid dysfunction can exacerbate or mimic heart failure symptoms; TSH measurement may be part of evaluation.
`I50.811`	Chronic combined systolic and diastolic heart failure	Long-term management may include periodic TSH assessment because thyroid status affects cardiac function.
`I50.812`	Acute on chronic combined systolic and diastolic heart failure	Acute decompensation assessment may include TSH to rule out thyroid-related contributors.
`I50.813`	Right heart failure	Part of comprehensive evaluation when symptoms could be influenced by metabolic or endocrine causes.
`I50.814`	Left heart failure	Thyroid abnormalities can impact left ventricular function; TSH testing may be relevant.
`I50.82`	Unspecified heart failure	Non-specific heart failure diagnoses where thyroid testing may be included in workup.
`I50.83`	High output heart failure	Thyrotoxicosis can cause high-output states; TSH is clinically relevant to detect hyperthyroidism.
`I50.84`	End stage heart failure	Pre-transplant or advanced care evaluations often include endocrine assessment including TSH.
`I50.89`	Other heart failure	Miscellaneous heart failure presentations where thyroid testing may contribute to diagnostic evaluation.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`80053`	Comprehensive metabolic panel	Frequently ordered concurrently to evaluate metabolic status and electrolyte, renal, and hepatic function when assessing fatigue or medication effects.
`85025`	Hemogram; automated and automated differential WBC count (CBC with diff)	Often ordered alongside TSH to evaluate overall hematologic status and to investigate causes of fatigue or systemic illness that can mimic thyroid dysfunction.