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Thyroid-Stimulating Hormone (TSH), Serum or Plasma
MessageTest Code
TSH - NOCO
Alias/See Also
Thyrotropin
CPT Codes
84443
Preferred Specimen
1 mL plasma from Green top (Lithium Heparin)
Minimum Volume
0.5 mL
Other Acceptable Specimens
1 mL serum from SST or Red Top
Specimen Stability
| Temperature | Time |
| Ambient | 5 days |
| Refrigerated | 5 days |
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Gross hemolysis, Collection after IV contrast material
Methodology
Setup Schedule
Monday through Sunday; Continuously
Report Available
Same day
Reference Range
Refer to the Chemistry Reference Range and Critical Results documents in the Resources file on the facility test directory page.
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.
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.
Performing Laboratory
Banner Fort Collins Medical Center Laboratory
North Colorado Medical Center Laboratory
Last Updated: August 13, 2026
