Quantifying amount of adsorption of levothyroxine by percutaneous endoscopic gastrostomy tubes.

Background: It has been the authors' clinical experience that hypothyroid patients who achieve a euthyroid state on a steady dose of oral levothyroxine often become hypothyroid over time if the medication is given via a feeding tube. The authors hypothesize that the tubing and enteral feeds may adsorb a significant percentage of the levothyroxine and thereby reduce its bioavailability. To the authors' knowledge, no previous research has been reported on this subject.