Sevelamer Carbonate Markedly Reduces Levothyroxine Absorption

Publisher: Bentham Science Publishers

E-ISSN: 2212-3873|14|3|206-209

ISSN: 1871-5303

Source: Endocrine, Metabolic & Immune Disorders-Drug Targets (Formerly Current Drug Targets - Immune, Endocrine & Metabolic Disorders), Vol.14, Iss.3, 2014-09, pp. : 206-209

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Abstract

We report the case of a young woman affected by hypothyroidism due to Hashimoto’s thyroiditis, previously well compensated with a full replacement therapy (150 mcg/day of levothyroxine), presenting a clinical picture of myxedema, with a TSH=650 mU/L. Two years earlier she had started a dialysis treatment because of a chronic renal failure and had been under treatment for the last 18 months with sevelamer carbonate, a phosphate binder. No improvement of clinical conditions nor reduction in TSH serum levels was observed even on increasing the dose of levothyroxine up to 300 mcg/day, whereas euthyroidism finally restored by administering the first morning dose of sevelamer carbonate at least 4 hours after levothyroxine administration. This case shows that sevelamer carbonate, in analogy with what has been already reported for sevelamer hydrochloride, can interfere with levothyroxine absorption leading to a condition of hypothyroidism in patients previously well compensated with a given replacement dose.