[Gender Disparities in Urolithiasis with a Special Focus on Oxalate Metabolism in the Liver]

The incidence and prevalence of urolithiasis are increasing in industrialized countries. In particular, an increase has been observed among young adults and women. The gender gap is closing, and gender equality (1:1) with regard to urolithiasis has already been documented for the USA. Studies have demonstrated that women have higher urine pH values than men, which promotes calcium phosphate crystallization. The tendency for men to develop calcium oxalate and uric acid stones is caused by the comparatively lower urine pH values. Malnutrition combined with a lack of exercise and the occurrence of metabolic syndrome with its underlying diseases (insulin resistance, type 2 diabetes mellitus, obesity, dyslipidaemia) are discussed as the causes of the increase in upper tract stone disease in industrialized countries. Non-alcoholic fatty liver disease (NAFLD), as the most common liver disease, is considered one of the complications of metabolic syndrome, with a prevalence of approximately 23% in Germany. Animal experiments and clinical studies have demonstrated a connection between NAFLD and increased oxalate excretion in urine. Based on the literature, NAFLD represents a possible cross-gender risk factor for kidney stone formation and is therefore considered to be a generally modifiable risk factor for recurrent urolithiasis. Simple recommendations concerning NAFLD should complement the general and metabolic workup in everyday clinical practice.