Summary & Overview
CPT 80438: Thyroid-Stimulating Hormone Stimulation Test, One-Hour
CPT code 80438 identifies a one-hour thyroid-stimulating hormone (TSH) stimulation test in which TSH is measured in three blood samples taken before and after administration of thyrotropin-releasing hormone. This assay is used to evaluate pituitary and thyroid responsiveness and can inform diagnosis and management of central hypothyroidism, tertiary hypothyroidism, and other disorders of the hypothalamic-pituitary-thyroid axis. Nationally, standardized coding for specialized endocrine stimulation tests is important for clinical documentation, claims processing, and consistent laboratory reimbursement.
Key payers addressed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise explanation of the clinical purpose and typical sites of service, followed by benchmarking and policy context relevant to laboratory and outpatient claims. The publication outlines common billing considerations and related service line implications, and it highlights where input data are not available in the source. Content aims to support coding accuracy, administrative workflows, and payer communications for facilities and laboratories handling endocrine stimulation testing.
Billing Code Overview
CPT code 80438 describes a thyroid-stimulating hormone (TSH) stimulation test in which a laboratory analyst measures TSH levels in three blood samples: one obtained before and two obtained after administration of thyrotropin-releasing hormone. This entry covers the one-hour protocol for TSH stimulation testing.
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Service type: Laboratory endocrine stimulation test
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Typical site of service: Clinical laboratory or hospital outpatient laboratory setting
Clinical & Coding Specifications
Clinical Context
A 42-year-old outpatient woman presents to an endocrinology clinic with symptoms of fatigue, weight changes, and irregular menses. The endocrinologist suspects central hypothyroidism versus primary thyroid disease and orders a thyrotropin-releasing hormone (TRH) stimulation test. The patient reports to the hospital outpatient laboratory fasting. Baseline blood is drawn (time 0), intravenous TRH is administered, and subsequent blood samples are collected at 20 and 60 minutes. The laboratory measures thyroid stimulating hormone (TSH) in each of the three samples to evaluate pituitary TSH response.
Workflow:
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Referral and order entry by the endocrinologist with diagnosis and fasting instructions.
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Patient check-in at outpatient laboratory or hospital-based phlebotomy area.
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Baseline venipuncture; TRH is administered intravenously per protocol.
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Timed blood draws at the specified intervals (baseline, ~20 minutes, ~60 minutes) with sample labeling and immediate transport to the clinical lab.
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Laboratory analyzer measures TSH in each specimen; results reported to ordering clinician for interpretation and further management.
Coding Specifications
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