Frontiers Thyroid hormones and carnitine in the second trimester negatively affect neonate birth weight: A prospective cohort study Targeting Skeletal Muscle Dysfunction With L Carnitine for the Treatment of Patients With Chronic Obstructive Pulmonary Disease In Vivo L carnitine reduces hyperthyroidism symptoms Levothyroxine (Synthroid) Supplement Interactions Supplements To Avoid While Taking Thyroid Hormones ConsumerLab.com If you are like a lot of people, you may have never heard of carnitine but this important nutrient is critical for our body's ability to optimally burn fat required for energy.