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 Complex Web of Interferences With Thyroid Function Tests Endocrine Practice Iodine Linus Pauling Institute Oregon State University Thyroid Supplement with L Carnitine for Cats Only Natural Pet Role of carnitine in disease Nutrition & Metabolism Springer Nature Link