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Thyroid Stimulating Hormone w/Reflex
MessageTest performed at York Hospital Laboratory.
- If TSH is abnormal, a Free T4 is performed.
Test Code
TSHR
Alias/See Also
TSH Reflex
CPT Codes
84443
Preferred Specimen
1.0 mL Serum
Transport Container
Serum Separator Tube
Transport Temperature
Refrigerated
Specimen Stability
Room temperature: 4 hours
Refrigerated: 7 days
Frozen: 4 weeks
Refrigerated: 7 days
Frozen: 4 weeks
Methodology
Chemiluminescence
Setup Schedule
Daily
Report Available
Next Day
Reference Range
Age | TSH (uU/mL) |
---|---|
<=4 Days | 1.0 - 39.0 |
1-4 Weeks | 1.7 - 9.1 |
1-12 Months | 0.8 - 8.2 |
1-19 Years | 0.7 - 5.7 |
Adult | 0.5 - 4.7 |
Clinical Significance
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. 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.