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In idiopathic uric acid nephrolithiasis, urinary pH and fractional excretion of urate are significantly lower than in control subjects, suggestive of defects in urinary acidification and urate excretion. Since these impairments are believed to be associated with primary gout, the underlying disturbance in idiopathic uric acid nephrolithiasis may be primary gout.

Ingestion of 2 gm AA daily results in no change in urinary pH but a moderate though statistically significant increase in urinary oxalate in NS (20%) and SF (33%). Stone formers respond no differently to AA than normal subjects. We recommend limiting AA use to less than 2 gm daily in CaOx stone formers.

Higher serum uric acid concentrations have been associated with higher bone mineral density in observational studies of older men and peri- or postmenopausal women, prompting speculation of a potential protective effect of uric acid on bone. Whether this relationship is present in the general population has not been examined and there is no data to support causality. We conducted a cross-sectional analysis of a probability sample of the US population. Demographic data, dietary intake, lifestyle risk factors and physical activity assessment data, serum biochemistry including serum uric acid, and bone mineral density were obtained from 6,759 National Health and Nutrition Examination Survey (NHANES; 2005-2010) participants over 30 years of age. In unadjusted analyses, higher serum uric acid levels were associated with higher bone mineral density at the femoral neck, total hip and lumbar spine in men, pre-menopausal women, and post-menopausal women not treated with estrogen. However, these associations were no longer statistically significant after adjustment for potential confounders, including age, body mass index, black race, alcohol consumption, estimated glomerular filtration rate (eGFR), serum alkaline phosphatase, and C-reactive protein (CRP). This is in contradistinction to some prevailing conclusions in the literature. To further examine the causal effect of higher serum uric acid on skeletal health, including biomechanical properties that are not measurable in humans, we used an established rat model of inducible mild hyperuricemia. There were no differences in bone mineral density, volume density, and biomechanical properties between hyperuricemic rats and normouricemic control animals. Taken together, our data do not support the hypothesis that higher serum uric acid has protective effects on bone health. This article is protected by copyright. All rights reserved