Urinary stone composition in Oman: with high incidence of cystinuria

Urinary stones are a common problem in Oman and their composition is unknown. The aim of this study is to analyze the components of urinary stones of Omani patients and use the obtained data for future studies of etiology, treatment, and prevention. Urinary stones of 255 consecutive patients were collected at the Sultan Qaboos University Hospital. Stones were analyzed by Fourier transform infrared spectrophotometer. The biochemical, metabolic, and radiological data relating to the patients and stones were collected. The mean age was 41 years, with M:F ratio of 3.7:1. The common comorbidities associated with stone formation were hypertension; diabetes, benign prostate hyperplasia; urinary tract infection; obesity; and atrophic kidney. The common presentation was renal colic and flank pain (96%). Stones were surgically retrieved in 70% of patients. Mean stone size was 9 ± 0.5 mm (range 1.3-80). Stone formers had a BMI ≥ 25 in 56% (P = 0.006) and positive family history of stones in 3.8%. The most common stones in Oman were as follows: Calcium Oxalates 45% (114/255); Mixed calcium phosphates & calcium oxalates 22% (55/255); Uric Acid 16% (40/255); and Cystine 4% (10/255). The most common urinary stones in Oman are Calcium Oxalates. Overweight is an important risk factor associated with stone formation. The hereditary Cystine stones are three times more common in Oman than what is reported in the literature that needs further genetic studies.