CPT® Code 80439

Thyrotropin releasing hormone (TRH) stimulation panel; 2 hour This panel must include the following: Thyroid stimulating hormone (TSH) (84443 x 4)

The CPT® Code 80439 refers to the Thyrotropin releasing hormone (TRH) stimulation panel, specifically designed for a 2-hour testing period. This panel is utilized to assess the functionality of the hypothalamus and pituitary gland in regulating thyroid hormones, particularly in cases of suspected pituitary (secondary) and tertiary (hypothalamic) hypothyroidism. The hypothalamus plays a crucial role in this regulatory process by releasing thyrotropin releasing hormone (TRH) when it detects low levels of the thyroid hormones T4 (thyroxine) and T3 (triiodothyronine) in the bloodstream. The release of TRH prompts the pituitary gland to secrete thyroid stimulating hormone (TSH), which subsequently stimulates the thyroid gland to produce and release T4 and T3. It is important to note that the TRH stimulation testing has become less common due to the introduction of the third-generation TSH test, which offers improved accuracy and reliability. Additionally, the availability of the necessary drug, Protirelin, for the TRH test has diminished. The procedure involves the insertion of an intravenous (IV) line, which is a separately reportable procedure. A baseline blood sample is collected from this IV line or through a separate venipuncture to measure initial TSH levels. Following this, Protirelin (TRH) is administered via IV push at a dosage of 200 mcg. For the 2-hour stimulation panel, blood samples are taken at three intervals: 20 minutes, 60 minutes, and 120 minutes post-administration to evaluate the TSH response. The serum or plasma samples obtained are then analyzed using a quantitative chemiluminescent immunoassay to determine the levels of TSH in the bloodstream.