Influence of body weight on biochemical alterations in patients with kidney stones

Jorge Quinchuela, Departamento de Hemodiálisis, Corporación Davita, Quito, Ecuador
Rubén Abdala, Departamento de Endocrinología, Instituto de Diagnóstico e Investigaciones Metabólicas IDIM, Buenos Aires, Argentina
Fernando Jerkovich, Departamento de Endocrinología, Hospital de Clínicas José de San Martín, Buenos Aires, Argentina
María B. Zanchetta, Departamento de Endocrinología, Instituto de Diagnóstico e Investigaciones Metabólicas IDIM, Buenos Aires, Argentina

Objective: To determine the prevalence of metabolic disorders in patients with kidney stones, to analyze sex-specific differences in anthropometric and biochemical parameters according to body weight, and to evaluate the association between body mass index (BMI) and key biomarkers, including creatinine, uric acid, urea, vitamin D, and parathyroid hormone (PTH). Material and methods: A retrospective observational study was conducted in adult patients with confirmed kidney stones. Participants were classified according to BMI as normal weight, overweight, or obese. Demographic, anthropometric, and biochemical data were obtained from medical records. Serum parameters included creatinine, calcium, phosphorus, uric acid, urea, sodium, potassium, vitamin D, and PTH. Urinary parameters included 24-hour urine volume, pH, creatinine, calcium, citrate, oxalate, magnesium, uric acid, sodium, and potassium. Results: Excess body weight was associated with a progressive increase in urinary uric acid excretion in both sexes. In obese men, significantly lower vitamin D levels, a more acidic urinary pH, increased urinary excretion of calcium, uric acid, and electrolytes, and a higher prevalence of diabetes and multiple metabolic disorders were observed. Overweight and obese women showed higher serum uric acid and urea levels, lower vitamin D concentrations, more acidic urinary pH, and increased urinary excretion of creatinine, phosphorus, uric acid, sodium, and potassium. Conclusions: Obesity is associated with pro-lithogenic metabolic and urinary alterations, including hyperuricemia, acidic urinary pH, and increased electrolyte excretion, which may contribute to an increased risk of kidney stone formation and recurrence.

Keywords: Kidney stones. Obesity. Metabolic profile. Body mass index.