renal disease (ESRD) in infancy. Bartter syndrome and the primary hyperoxalurias (PH) are the main causes of severe nephrocalcinosis with ESRD in infancy period. Bartter syndrome was ruled out because of the absence of hyponatremic hypokalemic metabolic alkalosis and recurrent dehydration attacks in our patient. Urinary chloride level was normal. Furthermore, SLC12A1 and CLCNKB gene analyses showed no mutation. Therefore, the most likely etiology in this infant with ESRD was the primary hyperoxalurias. The primary hyperoxalurias are autosomal recessive and rare metabolic disorders resulting from deficiencies of the hepatic peroxisomal enzyme alanine-glyoxlate aminotransferase (PH-1) and the enzyme glyoxylate reductase/hydroxypyruvate reductase (PH-2) which cause excessive oxalate formation and calcium oxalate deposition in various organs.1,2 The most common type of primary hyperoxaluria is type 1. Diagnosis relies on detection of increased levels of oxalate in urine (N: < 0.5 mmol/l/1.73m2 per day) and either assay enzyme activity from liver biopsy or molecular genetic testing of associated gene. Liver biopsy is still considered as the gold standard, but it is an invasive process and bears some risks. Genetic analysis provides some additional non-diagnostic information.1,2 However, the diagnosis of PH-1 was mainly established on the basis of clinical and radiologic findings in our case. Urine oxalate level could not be measured on admission due to financial problems of the family, and then urine output abruptly decreased.