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HelpTest Code TSH Thyroid Stimulating Hormone
Additional Codes
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Cerner |
NextGen |
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TSH |
Thyroid Stimulating Hormone (TSH) |
Alternate Name(s)
TSH
Thyrotropin
Thyrotropic Hormone
Methodology
(Vitros) Immunometric immunoassay, Chemiluminescent
Patient Preparation
None
Collection Instructions
Standard phlebotomy practices.
Specimen Requirements
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Container |
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Stability |
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Rejection Criteria |
Gross Hemolysis Turbid Specimens |
Result Reporting and Reference Values
Reported in µIU/mL
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Age |
Low |
High |
Critical Low |
Critical High |
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0 d-3 d |
1.0 |
20.0 |
N/A |
N/A |
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4 d-30 d |
0.5 |
6.5 |
N/A |
N/A |
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31 d-5 mo |
0.5 |
6.0 |
N/A |
N/A |
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6 mo-18Y |
0.5 |
4.5 |
N/A |
N/A |
Reflex Testing
None
Limitations
- Ortho reports a bias with the following:
- Biotin can cause a negative bias.
- Ortho reports no significant effect with the following:
- Bilirubin up to 20 mg/dL
- Hemoglobin up to 500 mg/dL
Useful For
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 elevated TSH.
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.