Laboratory Medicine
Test Directory / Thyroid Stimulating Hormone
Thyroid Stimulating Hormone
Brown clotted serum, gel barrier
| Test | Thyroid Stimulating Hormone |
|---|---|
| Common Abbreviations | TSH |
| Profile | Thyroid Function Test (TFT) |
| Tube type | Brown clotted serum, gel barrier |
| Clinical Indication | The 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 Type | Blood |
| Sample type | Serum |
| Minimum Volume | 0.5mL If requesting more than 10 tests please send an additional brown clotted serum sample. |
| Special Precautions | No special requirements |
| Stability | 8 days at 20 - 25°C, 14 days at 2 - 8°C and 24 months at -20°C |
| Turnaround Time | Inpatient: 24 hours Outpatient/ GP: 24 hours |
| Laboratory | York and Scarborough |
| Reference Interval | 0 - 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) |
| Limitations | Analysis 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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