Thyroxine (T4) and Thyroid-stimulating Hormone (TSH)
Also known as: T4 and TSH, TSH and T4
Use
This test is used to evaluate thyroid function and to diagnose thyroid disorders. Thyroxine (T4) and thyroid-stimulating hormone (TSH) levels are measured in serum or plasma. TSH is produced by the pituitary gland and stimulates the production and release of T4 from the thyroid gland. The levels of these hormones can help evaluate the functioning of the thyroid gland, detect any hormonal imbalance in the body, and assist in the diagnosis of conditions such as hypothyroidism and hyperthyroidism.
Special Instructions
This test may exhibit interference when the sample is collected from a person who is consuming a supplement with a high dose of biotin. Patients are recommended to stop biotin consumption at least 72 hours prior to the collection of a sample to avoid potential interference in test results.
Limitations
Biotin supplementation can interfere with the accuracy of the test results. Patients are advised to disclose biotin use to healthcare providers to minimize this risk. Interpretation of test results should consider individual physiological variations and be correlated with clinical and other laboratory findings.
Methodology
Immunoassay
Biomarkers
LOINC Codes
- 24348-5
- 11580-8
- 3026-2
Result Turnaround Time
1 day
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1 mL
Minimum Volume
0.7 mL
Container
Red-top tube, gel-barrier tube, or green-top (lithium heparin) tube
Collection Instructions
If a red-top tube or plasma is used, transfer separated serum or plasma to a plastic transport tube.
Patient Preparation
Patients should stop biotin consumption at least 72 hours prior to the collection of a sample.
Storage Instructions
Room temperature
Causes for Rejection
Plasma specimen
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | 14 days |