Alternative Names
  • Thyrotropin
  • Thyroid-stimulating Hormone

Test Code: 4013

CPT: 84443
Tests Included TSH
Use Used for evaluating thyroid function and disorders including hyperthyroidism or hypothyroidism. Human TSH released from the anterior pituitary is the principal regulator of thyroid function. The secretion of thyrotropin-releasing hormone (TRH or TRF) from the hypothalamus controls the secretion of hTSH. This system, in turn, regulates the release of the thyroid hormones thyroxine (T4) and triiodothyronine (T3). A negative feedback mechanism exists which is sensitive to the circulating concentrations of thyroid hormones, T3 and T4, monitored by the hypothalamus. Collectively, this system is referred to as the hypothalamo-hypophyseal-thyroid axis. Any alteration in the function of this axis can influence the levels of T4 and T3 in circulation.1,2
Clinical Utility Low TSH, Normal T4 & T3 - Probably Mild (subclinical) hyperthyroidism
Low TSH, High/Normal T4 and T3, Hyperthyroidism
Low TSH & Low/Normal T4 & T3, Non-thyroidal illness; rare pituitary (secondary hypothyroidism
Normal TSH & High T4 & T3, Thryroid Hormone resistance syndrome (a mutation in the thyroid hormone receptor decreases thyroid homrone High TSH, Normal T4 & T3, Mild (subclinical) hypothyroidism
High TSH, Low T4 & Low/Normal T3, Hypothyroidism
Intended Patient Population 18+ and Older Adult Males & Females
Patient Preparation None Specified
Sample Serum, Plasma
Tube Red, Green, Tiger
Volume 4mL Whole Blood (1mL Serum/Plasma)
Min Sample Volume 0.5 mLs
Reference Ranges M & F ≥ 18 yrs old; 0.340-5.600 uIU/mL
Analytical Measurement Range 0.016-100.000 uIU/mL
Units uIU/mL
Test Methodology Chemiluminescent Immunoassay
Test Turnaround Time 7 Days
Limitations Not suitable for neonatal testing
Shipping Requirements Refrigerated
Specimen Stability 7 Days RT
7 Days RF
Reject Criteria Hemolysis, Gross Lipemia
Laboratory Developed Test (LDT) Yes
CMS Guidance NCD 190.22
  1. Gornall AG, Luxton AW, Bhavnani BR. Endocrine disorders. Applied Biochemistry of Clinical Disorders 1986: 305-318. Edited by Gornall, A.G. Philadelphia, PA: J. B. Lippincott Co.
  2. Watts NB, Keffer JH. The thyroid gland. In Practical endocrine diagnosis 1982: 77-96. Philadelphia, PA: Lea Febiger.

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