Thyrotropin Releasing Hormone (TRH)

Test Code

CPT Codes
83519 <br>This test is not available for New York patient testing

Preferred Specimen
2 mL plasma aliquot, submitted in a plastic leak-proof tube (See Collection Instructions)

Minimum Volume
1 mL

5 mL EDTA specimen should be collected in the special TRH preservative tube and separated as soon as possible. Freeze specimen immediately after separation. Minimum specimen size is 1 mL.
Special preservative tubes are available from InterScience.

Important Precaution: Thyrotropin Releasing Hormone must be collected with the TRH Preservative. No other specimen is acceptable.
Ship specimens frozen on dry ice. This test is not valid unless it has been collected with the TRH Preservative available from ISI.

Transport Temperature

Specimen Stability
Room temperature: Unacceptable
Refrigerated: Unacceptable
Frozen: 6 months

Radioimmunoassay (RIA)

Setup Schedule
Set up: Mon-Fri; Report available: 11 business days

Reference Range
See Laboratory Report

Clinical Significance
Thyrotropin Releasing Hormone (TRH) is a tripeptide produced primarily by the hypothalamus. TRH is produced from a prohormone, which contains multiple copies of the TRH molecule meaning that several TRH entities can be released from one precursor. It has a stimulatory effect on the pituitary releasing thyrotropin (TSH). TRH secretion is controlled in a negative feedback system by thyroid hormones. Binding of TRH to its receptor causes a rise in calcium which initiates TSH secretion. It also stimulates adenyl cyclase in the pituitary. TRH also stimulates secretion of prolactin, growth hormone in acromegaly, and ACTH in Cushing's and Nelson's syndromes. Levels of TRH are nondetectable or very low in patients with hyperthyroidism and hypothalamic hypothyroidism. Levels are elevated in patients with primary and pituitary hypothyroidism.

Performing Laboratory
Inter Science Institute
944 W Hyde Park Blvd
Inglewood, CA 90302

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.