Thesis (M.Sc.) - Cairo University - Faculty of Medicine - Department of Pediatrics

Background: Most of the children with nephrolithiasis have a metabolic background of stone disease. Hence, early diagnosis of the renal stone type may target for dietary and pharmacological interventions that prevent its recurrence. Radiolucent renal stone may be composed of pure uric acid or dihydroxyadinine. Determination of radiolucent stone composition is of particular importance because uric acid stones can be treated with urinary alkalinization, while patients with DHA stones should be treated by allopurinol. Objective: Detect the prevalence of different types of radiolucent stones in pediatric age group. Methodology: The study was carried out on 50 pediatric patients with radiolucent renal stones following in nephrology clinic, Cairo university children{u2019}s hospital from July 2016 to February 2017. Analyzing of the epidemiology and clinical presentation were done, with specific investigations were carried out to determine the type of the radiolucent renal stones. Results: Forty percent of the cases the stone type was not determined, they had decreased activity of APRT enzyme but with residual more than 25%, and had no DHA crystals in their urine, while serum uric acid and urinary uric acid creatinine ratio were normal. Cases with high serum uric acid and urinary uric acid creatinine ratio were about 35%.whilePatients with DHA stones, diagnosed by APRT enzyme residual activity below 25% and presence of DHA crystals in urine, represented 12%. Conclusion: Prevalence of DHA renal stone is seriously under recognized and increasing the awareness of this disorder is highly important, proper examination of urinary crystal is diagnostic

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