Thyroid-stimulating hormone (TSH); free thyroxine, direct
This test may exhibit interference when sample is collected from a person who is consuming a supplement with a high dose of biotin (also termed as vitamin B7 or B8, vitamin H, or coenzyme R). It is recommended to ask all patients who may be indicated for this test about biotin supplementation. Patients should be cautioned to stop biotin consumption at least 72 hours prior to the collection of a sample.
Within 1 day
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Serum (preferred) or plasma
0.7 mL (Note: This volume does not allow for repeat testing.)
Red-top tube, gel-barrier tube, or green-top (lithium heparin) tube. Do not use oxalate, EDTA, or citrate plasma.
If a red-top tube or plasma is used, transfer separated serum or plasma to a plastic transport tube.
Citrate plasma specimen; improper labeling
Electrochemiluminescence immunoassay (ECLIA)
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