Can exercise affect thyroid function test results?

Yes, intense or prolonged exercise can affect thyroid function test results by temporarily altering thyroid hormone levels. Strenuous physical activity can increase the conversion of T4 to T3, potentially lowering TSH levels. This effect is generally short-lived, but it’s recommended to avoid heavy exercise in the hours before your thyroid test to prevent misleading results. Moderate exercise is less likely to impact your test. If you engage in intense workouts, inform your healthcare provider so they can interpret your results with that in mind.