Store at between 2-8°C for up to 7 days.
Store separated serum/plasma frozen if analysis is to be delayed.
The synthesis and secretion of TSH is stimulated by Thyrotrophin Releasing Hormone (TRH) in response to low levels of circulating thyroid hormones. TSH is formed in specific basophil cells of the anterior pituitary gland and is subject to a circadian secretion sequence. TSH has a stimulating action in all stages of thyroid hormone formation and secretion from the Thyroid gland. Determination of TSH serves as an initial test of thyroid function as levels will change in response to small changes in the concentrations of circulating free thyroid hormone levels.
Patients receiving therapy with biotin (> 5mg/day) should not have samples taken for analysis until at least 8 hours post dose.
TSH is measured as part of a TFT including fT4. Patients receiving therapy with biotin (> 5mg/day) should not have samples taken for analysis until at least 8 hours post dose. In rare cases, interference due to extremely high titers of antibodies to analyte or to analyte‑specific antibodies, streptavidin or ruthenium can occur. Please contact the laboratory for further advice if tests results are not consistent with the patient's medical history, clinical presentation and/or other findings, as further interference studies can be performed.
Adult reference range = 0.40-4.90 mIU/L