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Laboratory Medicine

Test Directory / Thyroid Stimulating Hormone

Thyroid Stimulating Hormone

Brown clotted serum, gel barrier

TestThyroid Stimulating Hormone
Common AbbreviationsTSH
ProfileThyroid Function Test (TFT)
Tube typeBrown clotted serum, gel barrier
Clinical IndicationThe ability to quantitate circulating levels of TSH is important in evaluating thyroid function. It is especially useful in the differential diagnosis of primary (thyroid) from secondary (pituitary) and tertiary (hypothalamus) hypothyroidism. In primary hypothyroidism, TSH levels are significantly elevated, while in secondary and tertiary hypothyroidism, TSH levels are low. Measurment of TSH is also used to monitor those patients receiving thyroid replacement therapy.
Specimen TypeBlood
Sample typeSerum
Minimum Volume0.5mL If requesting more than 10 tests please send an additional brown clotted serum sample.
Special PrecautionsNo special requirements
Stability8 days at 20 - 25°C, 14 days at 2 - 8°C and 24 months at -20°C
Turnaround TimeInpatient: 24 hours Outpatient/ GP: 24 hours
LaboratoryYork and Scarborough
Reference Interval0 - 6 Days: 0.7 - 15.2 mU/L 7 Days - 3 Months: 0.7 - 11.0 mU/L 3 Months -12 Months: 0.7 - 8.4 mU/L 1 Year - 6 Years: 0.7 - 6.0 mU/L 7 Years - 11 Years: 0.6 - 4.8 mU/L 12 Years - 20 Years: 0.51 - 4.3 mU/L Adults: 0.27 - 4.2 mU/L 1st Trimester: 0.33 - 4.6 mU/L 2nd Trimester: 0.35 - 4.1 mU/L 3rd Trimester: 0.21 - 3.2 mU/L (Quoted by the manufacturer)
LimitationsAnalysis should not be performed on haemolysed, icteric or lipaemic samples. The presence of autoantibodies may induce high molecular weight complexes (macroTSH) which may cause unexpected high values of TSH. The assay is unaffected by biotin < 1200 ng/mL. No interference was observed from rheumatoid factors up to a concentration of 1500 IU/mL. No interference was observed from IgG < 2.0 g/dL; IgM < 0.5 g/dL In vitro tests were performed on 16 commonly used pharmaceuticals. No interference with the assay was found. In addition, special thyroid drugs were tested. No interference was found. In rare cases, interference due to extremely high titres of antibodies to analyte specific antibodies, streptavidin or ruthenium can occur. Samples should not be taken from patients receiving therapy with high biotin doses (i.e. > 5 mg/day) until at least 8 hours following the last biotin administration. In vitro tests were performed on 16 commonly used pharmaceuticals. No interference with the assay was found. In addition, special thyroid drugs were tested. No interference was found. In rare cases, interference due to extremely high titres of antibodies to analyte specific antibodies, streptavidin or ruthenium can occur.
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