Abstract
Ammonium acid urate (AAU) crystal formation in the urine is also seen in children with nephrotic syndrome (NS). For this reason, we investigated the risk factors for AAU crystal formation in children with NS retrospectively. In pediatric nephrology, we confirmed that 85％ of patients presenting with AAU crystal formation were NS patients. The mean age was higher in pediatric NS patients than in general pediatric patients (7.8 ± 5.5 vs 2.2 ± 2.9 years old). Urinary pH was also higher in these patients than in general pediatric patients (6.7 ± 0.3 vs 6.3 ± 0.3). While 25 of 59 (42.4%) general pediatric patients were presented with acute enterocolitis, only 1 of 27 (3.7%) pediatric nephrology patients was presented with acute enterocolitis. Many of the patients examined seemed to have used a steroid, a diuretic drug or an albumin preparation, or have been subjected to infusion therapy. Blood and urinary analyses revealed that low serum total protein level, low serum albumin level, high blood urea nitrogen level, high serum total cholesterol level, high urinary protein-creatinine ratio, and high urinary hyaline cast level were risk factors for AAU crystal formation. Children with proteinuria caused by NS have a higher chance of AAU crystal formation than those without it. AAU crystal formation is linked to the risk of developing postrenal acute renal failure during the recovery phase of NS treatment. Thus, AAU crystal formation is a valuable predictor of the development of postrenal acute renal failure.
