L-carnitine supplementation for the management of fatigue in patients with hypothyroidism on levothyroxine treatment: a randomized, double-blind, placebo-controlled trial Hypothyroid patients experience fatigue-related symptoms despite adequate thyroid hormone replacement. Thyroid hormone plays an essential role in carnitine-dependent fatty acid import and oxidation. We investigated the effects of L-carnitine supplementation on fatigue in patients with hypothyroidism....