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Clinical Thyroidology

Letter: Desiccated Thyroid Extract Causes Nonphysiologic T3 Peaks

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To the Editor:

Hoang and associates once again raise the old question of a possible place for animal sources of desiccated thyroid extract (DTE) in the treatment of hypothyroidism (1). They stimulate new discussion but do not seem to break new ground. Of the 70 patients in their 16-week crossover study comparing DTE with l-thyroxine (L-T4), 49% preferred DTE and reported a subjective improvement in quality of life, although there were no statistically significant differences between the groups on psychometric testing. Those preferring DTE also had a 3- to 4-lb weight loss, but started with higher mean body weights than those in the L-T4 group (178.95 lb vs. 162.80 lb). Thyroid biochemical tests were within normal ranges in both groups. However, serum T3 levels were statistically higher (P

Exploring a role for DTE in the treatment of hypothyroidism with a well-designed, blinded, randomized clinical trial is laudable. However, when evaluating a therapy for a condition that affects millions of patients and for which an effective treatment already exists (4), this clinical trial should be powered and designed to detect adverse consequences. When the goal is physiologic replacement, care also needs to be exercised that normal physiology is restored. The study of Hoang and colleagues is provocative, but it does not achieve the minimum standard required to alter current clinical practice.

David S. Rosenthal, MD

Kenneth H. Hupart, MD

Division of Endocrinology, Diabetes and Metabolism
Nassau University Medical Center
East Meadow, NY


  1. Hoang TD, Olsen CH, Mai VQ, Clyde PW, Shakir MK. Desiccated thyroid extract compared with levothyroxine in the treatment of hypothyroidism: a randomized, double blind, crossover study. J Clin Endocrinol Metab 2013;98:1982-90. Epub March 28, 2013.
  2. Saberi M, Utiger RD. Serum thyroid hormones and thyrotropin concentrations during thyroxine and triiodothyronine therapy. J Clin Endocrinol Metab 1974;39:923-7.
  3. Biondi B, Wartofsky L. Combination treatment with T4 And T3: toward personalized replacement therapy in hypothyroidism? J Clin Endocrinol Metab 2012;97:2256-71. Epub May 16, 2012.
  4. Garber JR, Cobin RJ, Gharib H, et al. Clinical practice guidelines for hypothyroidism in adults: cosponsored by the American Association of Clinical Endocrinologists and the American Thyroid Association. Thyroid 2012; 22:1200-35. Epub November 6, 2012.