Microscopic hematuria is associated with low bone mineral density in aged women and men.

Little is known concerning renal or urological risk factors for osteoporosis. The aim of this study was to explore an association between urinalysis and bone mineral density (BMD) in 4,835 Japanese adults. Participants were 4,835 individuals (female 3,683; male 1,152) aged 50 years and over who received a health check-up between January 1995 and March 2006 in Japan. BMD of the distal radius and ulna of the non-dominant forearm was measured by the dual-energy X-ray absorptiometry (DXA) method using a DTX-200 Dexacare osteometer (Osteometer MediTech A/S, Rødovre, Denmark). Urine variables were protein, and red blood cells (RBCs) and white blood cells (WBCs) in urine sediment (categorized as <1, 1-4, 5-9, or >or=10 cells per high-power microscopic field). Average age was 58.9 years (SD 5.6) in women, and 60.5 years (SD 6.2) in men. Simple linear regression analysis showed that urinary RBCs were associated with BMD in women (beta = or-5.88 x 10(-3), R (2) = 0.004, p < 0.0001) and men (beta = or-1.34 x 10(-2), R (2) = 0.013, p = 0.0001). These associations held when possible confounders were adjusted (beta = or-2.05 x 10(-3), R (2) = 0.001, p = 0.0338 for women and beta =or -5.67 x 10(-3), R (2) = 0.006, p = 0.0163 for men). Microscopic hematuria is associated with forearm BMD in women and men aged 50 years and over. Further studies should be conducted to determine the mechanisms underlying this association.