WEIGHT LOSS AND VARIATION OF LEVOTHYROXINE (L-T4) REQUIREMENTS IN HYPOTHYROID OBESE PATIENTS AFTER BARIATRIC SURGERY.

WEIGHT LOSS AND VARIATION OF LEVOTHYROXINE (L-T4) REQUIREMENTS IN HYPOTHYROID OBESE PATIENTS AFTER BARIATRIC SURGERY.

Thyroid. 2016 Feb 19;

Authors: Fierabracci P, Martinelli S, Tamberi A, Piaggi P, Basolo A, Pelosini C, Ricco I, Magno S, Querci G, Ceccarini G, Scartabelli G, Salvetti G, Vitti P, Santini F

Abstract
BACKGROUND: Obesity and hypothyroidism are both common disorders within the general population. Obese hypothyroid subjects require higher doses of L-T4 as compared to normal weight individuals. Previous studies on the effects of bariatric surgery on L-T4 dose requirements in hypothyroid subjects provided conflicting results. The aim of this study was to evaluate the L-T4 requirements in a group of obese subjects with acquired hypothyroidism, before and after weight loss achieved by bariatric surgery.
METHODS: Ninety-three obese hypothyroid subjects (age: 48 ± 9 yrs, BMI: 45.9 ± 5.6 kg/m2), were evaluated before and 28 ± 8 months after bariatric surgery. Changes in the L-T4 dose, anthropometric measures, and hormone values were evaluated. In 20 patients data of body composition, assessed by dual energy X-ray absorptiometry, were also analyzed.
RESULTS: On average, after weight loss, a significant reduction of the total dose of L-T4 was documented (from 130.6 ± 48.5 to 116.2 ± 38.6 µg/day, p<0.001). The L-T4 dose had to be reduced in 47 patients, it was unchanged in 34 while it had to be increased in 12 patients affected by autoimmune thyroiditis. Reduction of the L-T4 dose was proportional to reduction of the lean mass.
CONCLUSIONS: The weight loss that is achieved with modern surgical bariatric procedures is associated with a reduction of L-T4 requirements in most hypothyroid subjects, which appears related to a decrease of the lean mass. Occasionally, a concurrent decline of residual thyroid function, as it occurs in autoimmune thyroiditis, can counteract this phenomenon and eventually produce an increase of L-T4 needs. We believe that during the weight loss phase that follows bariatric surgery there is no need for preventive adjustments of the L-T4 dose, but serum thyroid hormones and TSH should be periodically monitored, to detect possible variations of L-T4 requirements and to allow proper corrections of the therapy.

PMID: 26895690 [PubMed - as supplied by publisher]

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