Abstract
We are pleased to receive the astute comments submitted by Dr. Hennessey regarding our recent report (1) that demonstrated the interfering effect of concurrent 2% milk ingestion on oral levothyroxine absorption. We confirm that the reported results are not adjusted for each subject's endogenous serum total thyroxine (TT4) concentration. Although our study design did not permit us to perform these calculations using the preferred method (Method 3) referenced by Blakesley et al. (2) and thus we provide them alongside this reply, the potentially even greater difference in the areas under the curve is notable. We appreciate this important statement suggesting that not adjusting for endogenous TT4 concentrations decreases our ability to even further demonstrate the effect of milk as an interfering substance on oral levothyroxine absorption.