Immunotherapy-Associated Hypothyroidism: Comparison of the Pre-Existing With Hypothyroidism.

Abstract

822 patients were screened, with 85 determined to have pre-existing hypothyroidism, 48 de-novo primary hypothyroidism and 12 de-novo hypophysitis. All groups displayed fluctuations in TFTs around weeks 6-8 of treatment. In the pre-existing hypothyroidism group, the levothyroxine dose was higher at 54 weeks than at baseline with the difference showing a trend towards statistical significance (p=0.06). The observed mean levothyroxine dose was significantly lower than the mean calculated weight-based dose for all groups. This finding was most clinically significant for the de-novo hypophysitis group (mean difference: -58.3 mcg, p<0.0001). The mean 0.9 mcg/kg levothyroxine dose at week 54 for the de-novo hypophysitis group was statistically lower than the other groups (p=0.009).