A clinical study on radiolucent (uric acid) stones in tertiary care centre

Background: Uric acid nephrolithiasis is characteristically a manifestation of a systemic metabolic disorder. It has a prevalence of about 10% among all stone formers, the third most common type of kidney stone. Uric acid stones form primarily due to an unduly acid urine; less deciding factors are hyperuricosuria and a low urine volume. Aim and objectives: To study and analyze the age and sex distribution of uric acid urolithiasis, to study and identify the predisposing and causative factors and treatment of uric acid urolithiasis. Methods and materials: The materials for the clinical study on radiolucent (uric acid) stones were selected from the cases presenting with pain in loin attended to urology department in King George Hospital, Visakhapatnam from October 2015 to December 2017. The selection of cases was based on clinical symptoms and radiological findings. The number of cases studied was 50. A detailed history, physical examination, blood and urinary examination were done. X-ray KUB, ultrasound KUB, plain CT KUB was done. Patients were treated either medically or surgically depending upon their condition. Results: Out of the 50 patients enrolled, there were 36(72%) male and 14 (28%) female patients. Most of the patients (40%) were in the age group 41-50 years. Pain was the most common symptom (100%) followed by nausea and vomiting. Serum creatinine was normal in 84% of cases. Serum uric acid and Serum electrolytes were normal in all the 50 patients. Urine volume was normal (> 2 litres/24 hrs) in 44% of cases. Urine pH was < 5.5 in 92% and urine uric acid is normal in 100% of cases. In the present study, out of 50 patients, 38(76%) were managed conservatively with potassium citrate and 12 patients were treated with various surgical interventions. Conclusions: Uric acid calculi are more common in men (M: F ratio 2.5:1). Uric acid calculi are caused mostly due to low urinary pH and low urine volume. Type 2 diabetes mellitus and high body mass index (BMI) are independent risk factors for uric acid stones. Most of the uric acid calculi can be treated conservatively with potassium citrate (30-40 meq/day) in two divided doses.