Thyroid Thursday #76: Can Carnitine Make Your Hypothyroid Symptoms Worse? L carnitine supplementation for the management of fatigue in patients with hypothyroidism on levothyroxine treatment: a randomized, double blind, placebo controlled trial. Semantic Scholar The most common cause of hypothyroidism worldwide is insufficient intake of iodine, a mineral found in iodized salt and some foods (such as seafood and dairy) that is needed for production of Altered carnitine acylcarnitine profiles in levothyroxine treated congenital hypothyroid patients with fatigue: An LC MS MS based study from Bangladesh PLOS One