A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # |
Thyroid Stimulating Hormone
Test CodeCPT Codes
84443
Preferred Specimen
Serum (gold or red top tube)
Minimum Volume
Transport Container
Serum (gold or red top) tube
Transport Temperature
Specimen Stability
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Methodology
Chemiluminescence
Setup Schedule
Daily upon receipt
Report Available
Limitations
Reference Range
0.465 - 4.68 mIU/mL
Clinical Significance
TSH secretion by the anterior pituitary is controlled by thyrotropin releasing hormone, a tripeptide produced by the hypothalamus. TSH stimulates the production of thyroxine (T4) and triiodothyronine (T3) by the thyroid gland. The circulating free fractions of T4 and T3 in turn regulate the secretion of TSH by a negative feedback mechanism at the pituitary and possibly the hypothalamus. The diagnosis of overt hypothyroidism by the finding of a low total T4 or free T4 concentration is readily confirmed by a raised TSH concentration. Measurement of low or undetectable TSH concentrations may assist the diagnosis of hyperthyroidism, where concentrations of T4 and T3 are elevated and TSH secretion is suppressed. TSH tests with high levels of precision and functional sensitivity claims of 0.01–0.02 mIU/L have been termed “third generation” tests. These have the advantage of discriminating between the concentrations of TSH observed in thyrotoxicosis, compared with the low, but detectable, concentrations that occur in subclinical hyperthyroidism.