Cortisol · Thyroid

Chronic cortisol slows peripheral T4 → T3 conversion, raises rT3 and desensitises thyroid receptors — while TSH stays perfectly normal. This is the most common scenario behind "unexplained" fatigue after 40.

This exploration describes the tandem both ways: what stress does to the thyroid, what a missed hypothyroidism does to the adrenals, and how to break the loop without stacking supplements.