Investigation of the background of sex differences in uric acid excretion

Abstract

We reported that serum uric acid levels in postmenopausal women and men no longer differ significantly, but uric acid excretion is significantly higher in women. To clarify the background of this sex difference, we added further analysis to the data. Twenty-three men aged 50 years or older (male group, mean age: 67 ± 10 years) and 26 postmenopausal women (female group, mean age: 73 ± 9 years) were included in the analysis. Serum uric acid levels were 5.2 ± 1.0 mg/dL in the male group and 4.9 ± 1.2 mg/dL in the female group (p = 0.361). The urinary UA/Cr ratio was 0.48 ± 0.12 in the male group and 0.67 ± 0.20 in the female group (p < 0.001). The urinary pH was 5.7 ± 0.7 in the male group and 6.0 ± 1.1 in the female group (p = 0.252). In the male group, the only correlation finding was between the urinary UA/Cr ratio and salt intake (r=0.641, p<0.001). In the female group, the urinary UA/Cr ratio showed a strong positive correlation with salt intake (r=0.673, p<0.001), potassium excretion (r=0.580, p<0.003), and urinary pH (r=0.552, p<0.003). These results suggest that sex differences in urinary uric acid excretion in relation to potassium excretion and urinary pH remain after menopause.