745 Age and gender specific reference values for renal volume and association with risk factors for chronic kidney disease in a general population

Abstract Background and Aims Renal volume (RV) is associated with renal function and with a variety of cardiovascular risk factors (CVRF). We analyzed RV by magnetic resonance imaging (MRI) in a large population-based study (Study of Health in Pomerania; SHIP-TREND) and tested the influence of age, sex, smoking status, BSA, systolic and diastolic blood pressure, type 2 diabetes, HDL-C, LDL-C, estimated glomerular filtration rate (eGFR) and uric acid on RV. Method 1,815 participants without kidney disease (930 women) aged 21-81 years were included in our study. Right and left RV with and without body surface area (BSA) indexation were compared among three age groups (22-39 years, 40-59 years, 60-81 years) by median and interquartile range and tested separately in women and men. Results eGFR, uric acid, right and left RV were higher in men compared to women (all p < 0.001). Left kidney were larger than right kidneys (both sexes). With age, RV showed a continuously decreasing trend in women and an upside down U-shape relation in men. In multivariable linear regression models, current smoking (β = 14.96, 95% CI 12.12; 17.79), BSA (β = 97.66, 95% CI 90.4; 104.93), diastolic blood pressure (β = 0.17, 95% CI 0.01; 0.32), and eGFR (β = 0.57, 95% CI 0.50; 0.65) were positively associated with both left and right renal volume whereas uric acid (β = −0.03, 95% CI −0.05; −0.01) showed an inverse association with RV. Interestingly, the same eGFR correlated with higher RV in men compared to women. Conclusion Reference values for RV are different for age-groups and sex. For any given age, female kidneys are smaller than male kidneys. RV associates positively with eGFR, but for any chosen eGFR, renal volume in females is lower compared to males. RV decreases with age, but in men, RV first increases in the age group 40-59 years before finally decreasing with a faster decline after 60 years. This may reflect hyperfiltration and glomerular hypertrophy associated with the presence of CVRF.