Oral Liquid l-Thyroxine (l-T4) May Be Better Absorbed Compared to l-T4 Tablets Following Bariatric Surgery

OBES SURG (2013) 23:14931496 DOI 10.1007/s11695-013-1015-y

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Oral Liquid L-Thyroxine (L-T4) May Be Better Absorbed Compared to L-T4 Tablets Following Bariatric Surgery

Ilenia Pirola & Anna M. Formenti & Elena Gandossi &

Francesco Mittempergher & Claudio Casella &

Barbara Agosti & Carlo Cappelli

Published online: 4 July 2013# The Author(s) 2013. This article is published with open access at Springerlink.com

Abstract Drug malabsorption is a potential concern after bariatric surgery. We present four case reports of hypothyroid patients who were well replaced with thyroxine tablets to euthyroid thyrotropin (TSH) levels prior to Roux-en-Y gastric bypass surgery. These patients developed elevated TSH levels after the surgery, the TSH responded reversibly to switching from treatment with oral tablets to a liquid formulation.

Keywords Severe obesity . Roux-en-Y gastric bypass surgery . L-thyroxine . Liquid formulation . Absorption

Introduction

Global demand for bariatric surgery has increased dramatically in the past decade [1]. This procedure refers to various surgical techniques employed for achieving weight loss.

Drug malabsorption is a potential postsurgical concern, particularly after diversionary procedures, for many reasons. Nearly all oral agents are maximally absorbed in the small intestine, which is bypassed in several bariatric procedures.

Delayed gastric emptying, diminished opportunity for mucosal exposure, and changes in drug dissolution and solubility resulting from alterations in intestinal pH are additional factors that may potentially impair drug absorption [2, 3].

Levothyroxine (L-T4) is an effective replacement therapy for patients with hypothyroidism or suppressive therapy after surgical removal of thyroid cancer [4, 5]. Absorption of L-T4 is reduced when it is ingested concomitantly with other drugs or with coffee [6] and also when gastric pH is altered by autoimmune gastritis or by infection with Helicobacter pylori [7, 8]. Evidence for diminished L-T4 absorption has been reported in patients after bariatric surgery [3, 9, 10].

We observed an increase in serum thyrotropin (TSH) levels after bariatric surgery in a previously euthyroid patient receiving L-T4 in tablet form. This condition was reversibly resolved by switching to the same dose in a liquid oral formulation. We subsequently identified three additional stable hypothyroid patients submitted to bariatric surgery, who normalised serum TSH after switching from tablets to the oral liquid formulation.

Patients and Methods

Serum concentrations of free thyroxine (fT4; normal range,8.019.0 pg/mL;...