Field

Other biochemistry and Endocrine tests/Tumor markers

Specimen Type

Serum

Specimen Requirements

Special Requirements

Many factors can affect the thyroid profile tests (collection time, fasting, calorie intake, drugs, etc.) Therefore suggest to taking blood samples under the same conditions each time for the thyroid profile.
Preferred Sample Collection Time: Morning (Most preferably 6:00 AM to 10:00 AM)

Condition: Before taking any thyroxine medication, it is preferable to fast when collecting the sample.

Rationale: TSH levels exhibit significant diurnal variation, peaking between 11:00 PM and 5:00 AM and reaching a nadir

between 5:00 PM and 8:00 PM.

TSH levels appear to be lower after food.

FT4 levels appear to be higher just after taking a thyroxine dose.

Exceptions: If a relevant consultant has recommended that a sample to be collected beyond the above requirements, please ensure this is sent a note

TAT

5 hours