Renal net acid excretion capacity is comparable in prepubescence, adolescence, and young adulthood but falls with aging

Abstract

OBJECTIVES: To evaluate whether renal net acid excretion capacity (NAEC) varies across different age groups and, specifically, whether it falls in elderly people. DESIGN: Cross-sectional observational study. SETTING: Community-based. PARTICIPANTS: Young participants were from the DOrtmund Nutritional and Anthropometric Longitudinally Designed Study, Dortmund, Germany; elderly participants were from Gothenburg, Sweden. MEASUREMENTS: Twenty-four-hour urine pH, net acid excretion (NAE), urinary phosphorus, total nitrogen excretion, and anthropometric data were measured in healthy elderly people (aged 55-75; n=85), young adults (aged 18-22; n=117), adolescents (aged 13-14; n=112), and prepubescent children (aged 6-7; n=217). NAEC was determined as 24-hour NAE adjusted for urine pH using the residual method. RESULTS: In elderly participants 24-hour urinary pH (5.9±0.53) was lower (P