Meuwese CL, et al. - Using cross-sectional and longitudinal analyses in individuals from all adult age groups, researchers assessed the impact of thyroid hormone alterations on renal function. They analyzed individual participant data from 16 independent cohorts which measured thyroid stimulating hormone, free thyroxine levels, and creatinine levels. By fitting linear regression models and linear mixed models in each cohort separately, they calculated estimated glomerular filtration rates (eGFR) at baseline and eGFR change during follow-up. Low thyroid function was not shown to be related to a deterioration of renal function. Renal dysfunction causing thyroid hormone alterations could explain the cross-sectional link.