L-carnitine found to be complementary therapy for hyperthyroidism




Journal of Clinical Endocrinology and Metabolism

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Consumer Data: Hyperthyroidism L-Carnitine Passionflower
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The thyroid secretes hormones that influence virtually every organ. Thyroid hormone is required for growth and development in children. In adults, its primary job is to regulate the production of metabolic energy. The thyroid governs the "basal metabolic rate," which is a measure of how efficiently the body turns calories into useable heat energy. In hyperthyroidism, the thyroid gland is overactive and secretes too much thyroid hormone. Excess thyroid hormone can cause rapid heartbeat and the body temperature is elevated. The hyperthyroid individual may experience extreme weight loss, in spite of a huge appetite, because they burn up calories too fast. Hyperthyroidism can make a person nervous, emotionally unstable, and unable to sleep.

In the past, animal studies have indicated that L-carnitine may be useful in treating hyperthyroidism. L-carnitine is an amino acid that is made in the human body and for this reason, L-carnitine is usually not considered to be an essential nutrient. Recently, a group of researchers in Italy decided to evaluate whether or not this nutrient could prove to be a beneficial complementary therapy for individuals with hyperthyroidism.

The study, published in the August 2001 edition of the Journal of Clinical Endocrinology and Metabolism, assessed 50 women who were randomly assigned to one of five groups. In this randomized, double-blind, placebo-controlled study, the authors set out to determine if L carnitine at a dose of 2 or 4 grams per day would be able to reverse and/or prevent/minimize nine identified symptoms related to hyperthyroidism. In addition, they were interested to see if supplementation with carnitine would improve bone mineral density.

The results of this six-month assessment were positive in all cases. In fact, the benefits were present whether the patient received the 2-gram dose or the 4-gram dose. The findings led the authors of this study to conclude that, “L-carnitine is effective in both reversing and preventing symptoms of hyperthyroidism and has a beneficial effect on bone mineralization. Because hyperthyroidism depletes the body deposits of carnitine and since carnitine has no toxicity, teratogenicity, contraindications and interactions with drugs, carnitine can be of clinical use.”1


1. Benvenga S, et al. Usefulness of L-carnitine, a naturally occurring peripheral antagonist of thyroid hormone action, in iatrogenic hyperthyroidism: a randomized, double-blind, placebo-controlled clinical trial. J Clin Endocrinol Metab. Aug 2001;86(8):3579-94.