Konishi A, Ida S, Shoji Y, et al. - This study was undertaken to explore age‐dependent differences in thyroid hormone levels in Prader‐Willi syndrome (PWS) children. Researchers retrospectively compared free T4 (FT4), free T3 (FT3), and thyroid‐stimulating hormone concentrations between genetically confirmed PWS children (N = 43, median age: 11.2 months) and controls (N = 85, median age: 14.5 months) matched for age, gender, body weight‐SD score (SDS), height‐SDS, body mass index‐SDS and serum albumin level, a marker of the nutritional status. Individuals were subcategorized into two groups based on their age: an infant group aged between 1 and 11 months (PWS: N = 22, controls: N = 30) and a toddler group aged between 12 and 47 months (PWS: N = 21, controls: N = 55). The outcomes of this study illustrated that infants with PWS had lower FT4 levels, but FT3 levels were normal, indicating that the levothyroxine replacement therapy may not need to be routinely performed.