Optimum Time and Conditions for Thyroid Blood Tests

Article discusses how fasting and time of day of testing can alter TSH results.

...The Thyroid Manager online textbook mentions that Serum T4 concentrations peak 2 to 4 hours after an oral dose and remain above normal for approximately 6 hours in patients receiving daily replacement therapy.

For this reason, thyroid expert Richard Shames, MD has the following recommendation:

I absolutely recommend that patients have any morning blood tests evaluating the thyroid before taking any thyroid medication. I have always told my patients to do it this way.


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