Thyroid Blood Tests to Diagnose a Thyroid or Hormone Imbalance

A healthy thyroid produces mostly T4 and just a little T3 [1], so the most important thyroid blood test is the total T4, because that indicates whether there is even enough thyroid hormone to work with.  Free T4 (FT4) can be artificially elevated from certain drugs like aspirin, diuretics, or heparin, so it is important … Read more

Thyroid Lab Results are Affected by the Time of Your Last Dose

T3 containing medications (such as desiccated thyroid or Cytomel) cause a peak in Free T3 levels a few hours after ingestion (42% within the first 4 hours), and then a decline until the next dose. [1]  Even T4 medications like Synthroid or levothyroxine cause a small bump in thyroid levels a few hours after a dose (16% … Read more

Thyroid Reference Ranges are too Broad; What is Healthy / Optimal?

Thyroid reference ranges are misleadingly broad, and many are told they are “fine” (when they are actually hypothyroid), simply because they’re within the reference range.  My research indicates that most people in good health have values in the upper half of the range for Total T4 and Free T3.  Free T4 should be mid-range or … Read more

TSH Levels Fluctuate and often do not Reflect Thyroid Levels

TSH fluctuates

TSH (Thyroid Stimulating Hormone) levels are used by American endocrinologists to diagnose and treat thyroid problems.  The following is from the first paragraph of the American Association of Clinical Endocrinologist Medical Guidelines: The sensitive thyroid stimulating hormone (TSH or thyrotropin) assay has become the single best screening test for hyperthyroidism and hypothyroidism, and in most … Read more