Millions of individuals worldwide have used supraphysiologic doses of anabolic-androgenic steroids (AAS) for athletics or personal appearance, but their effects on the kidney remain little studied.1 In a recent cross-sectional cohort study evaluating cardiovascular function in 57 current AAS users, 28 past users, and 52 non–AAS-using weightlifters,2,3 we obtained participants’ standard chemistries, hematology, cystatin C, and endocrine measurenents (details in Item S1). We used these data to calculate participants’ estimated glomerular filtration rates (eGFRs), based on serum creatinine and cystatin C levels (eGFRcr-cys), using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation.