title: Sevelamer carbonate markedly reduces levothyroxine absorption.
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.
authors.forename: Michele
authors.initials: M
authors.lastname: Iovino
authors.forename: Nicola
authors.initials: N
authors.lastname: Iovine
authors.forename: Alfanso
authors.initials: A
authors.lastname: Petrosino
authors.forename: Vito A
authors.initials: VA
authors.lastname: Giagulli
authors.forename: Brunella
authors.initials: B
authors.lastname: Licchelli
authors.forename: Edoardo
authors.initials: E
authors.lastname: Guastamacchia
authors.affiliation: Endocrinology and Metabolic Diseases, Eboli Hospital, Salerno, Italy. micheleiovino06@tin.it.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Triggiani
mesh_terms: D000328:Adult; D004334:Drug Administration Schedule; D004347:Drug Interactions; D005260:Female; D050031:Hashimoto Disease / Q000188:drug therapy / Q000378:metabolism*; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects; D009230:Myxedema / Q000139:chemically induced; D011073:Polyamines / Q000008:administration & dosage / Q000009:adverse effects*; D006435:Renal Dialysis / Q000009:adverse effects; D051436:Renal Insufficiency, Chronic / Q000150:complications / Q000378:metabolism / Q000628:therapy; D000069603:Sevelamer; D013974:Thyroxine / Q000493:pharmacokinetics* / Q000627:therapeutic use
chemical_list: D011073:Polyamines; D000069603:Sevelamer; D013974:Thyroxine