Role of carnitine in disease Nutrition & Metabolism Springer Nature Link Frontiers Association between fatigue, peripheral serotonin, and L carnitine in hypothyroidism and in chronic fatigue syndrome Successive thyroid storms treated with L carnitine and low doses of Methimazole The American Journal of Medicine 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.