Effects of Bodybuilding Supplements on the Kidney: A Population-Based Biopsy Study among Middle Eastern Men

Abstract

Background: The incidence of kidney diseases among bodybuilders is unknown. Methods: Between January 2011 and December 2019, the Iraqi Kurdistan 15 to 39 year old male population averaged 1,100,000 with approximately 24,000 regular and 56,000 total gymnasium participants. In that period, 15 participants had kidney biopsies. Annual age specific incidence rates (ASIR) with (95% confidence intervals) per 100,000 bodybuilders were compared with the general age-matched male population. Results: Among regular participants, diagnoses were: focal segmental glomerulosclerosis (FSGS), 2; membranous glomerulonephritis (MGN), 2; post-infectious glomeruonephritis (PIGN), 1; tubulointerstitial nephritis (TIN), 1; and nephrocalcinosis , 2. Acute tubular necrosis (ATN) was diagnosed in 2 newcomers and 5 regular participants. Anabolic steroids use was self-reported in 18%, protein powders in 71%, creatine in 29%, and veterinary grade vitamin D injections in 2.6% of regular participants. ASIR for FSGS, MGN, PIGN, and TIN among regular participants was not statistically different than the general population. ASIR of FSGS adjusted for anabolic steroid use was 5.1 (-0.2 to 12.3), a rate overlapping with FSGS in the general population at 2.0 (1.2 to 2.8). ATN presented with muscle pain and myoglobinuria among inexperienced bodybuilders and appeared secondary to exertional muscle injury. ASIR for ATN among total participants at 1.4 (0.4 to 2.4) was not considered significantly different than for the general population at 0.3 (0.1 to 0.5). Nephrocalcinosis was only diagnosed among bodybuilders at a 9-year cumulative rate of one per 314 vitamin D injectors. Conclusions: Kidney disease rates among bodybuilders was not significantly different than for the general population, except for nephrocalcinosis that was caused by injections of veterinary grade vitamin D compounds.