Serum Thyrotropin Levels Following Levothyroxine Administration at Breakfast

Abstract

Hypothyroidism is treated with oral levothyroxine. Some patients fail to attain adequate control because of poor compliance. Delaying breakfast to take levothyroxine on an empty stomach can decrease adherence to hypothyroidism treatment. The objective of this study was to evaluate whether administering levothyroxine with breakfast can maintain thyrotropin (TSH) levels in the therapeutic range, without major clinical changes. A prospective, randomized, open-label, crossover study was conducted to compare usual levothyroxine administration while in a fasting state with administration during breakfast. From September 2008 to April 2009, 45 patients with primary hypothyroidism who received levothyroxine were recruited. The patients completed 180 days of the protocol and were randomized to 90 days of each levothyroxine administration regimen (while fasting or with breakfast). Clinical and biochemical analyses were performed at baseline and on days 45, 90, 135, and 180. The primary outcome was TSH level. Forty-two patients completed the protocol. The TSH level was higher for levothyroxine administration with breakfast than while fasting (2.89 vs. 1.9 mIU/L, p=0.028). Uncontrolled hypothyroidism (TSH ≥3.5 mIU/L) occurred regardless of the type of levothyroxine administration (p=0.26). No risk factors were identified for TSH elevation. Levothyroxine administration with breakfast could be an alternative regimen for patients who have adherence difficulties due to the need for delaying intake, and is more likely to cause variability in the TSH level, meaning the patient should be followed more closely. For patients in whom a specific serum TSH goal is important, taking levothyroxine while fasting is recommended.