Thyroid dysfunction is one of the most commonly missed diagnoses in conventional medicine, not because doctors fail to test for it, but because most doctors only test TSH and stop there. TSH, the thyroid stimulating hormone, is a pituitary signal to the thyroid. It does not directly measure how much active thyroid hormone your body has available at the cellular level.
The Complete Thyroid Picture
A full thyroid assessment requires TSH, Free T3, Free T4, and often Reverse T3. Free T3 is the active thyroid hormone that enters cells and drives metabolism, energy, mood, and cognition. Free T4 is the precursor. The conversion of T4 to T3 happens peripherally and can be impaired by chronic stress, inflammation, nutrient deficiencies, and other factors. Reverse T3 is an inactive isomer of T3 that competes for the same receptor and can block thyroid action even when Free T3 looks adequate.
Subclinical Hypothyroidism
Subclinical hypothyroidism is defined as elevated TSH with normal Free T4. But many patients experience significant symptoms including fatigue, weight gain, brain fog, hair loss, and cold intolerance with TSH values in the upper range of normal, particularly above 2.5 mIU/L, even without an official diagnosis of subclinical hypothyroidism.
The Conversion Problem
Some patients convert T4 to Reverse T3 preferentially rather than to Free T3. This cellular hypothyroidism can occur with normal TSH and normal Free T4. The only way to identify it is to test Reverse T3 and calculate the Free T3 to Reverse T3 ratio. AI Matrix Health includes this analysis in comprehensive panels.
Treatment Options
When thyroid optimization is indicated, options include T4 monotherapy, T4 and T3 combination therapy, or desiccated thyroid extract which contains both T4 and T3 naturally. Protocol selection depends on your specific pattern of thyroid biomarkers. AI Matrix Health is available in all 50 states.