Frontiers Association between fatigue, peripheral serotonin, and L carnitine in hypothyroidism and in chronic fatigue syndrome Hypothyroidism is a condition where the thyroid gland does not produce enough thyroid hormone which is crucial to regulate the body's metabolism and growth development. There can be various causes that contribute Fatigue and Brain Fog Kit Rootcology Frontiers Thyroid hormones and carnitine in the second trimester negatively affect neonate birth weight: A prospective cohort study