Congenital hyperoxalosis: a rare metabolic disorder in a term neonate with perinatal autopsy findings

Introduction: Primary hyperoxaluria (PH) is a rare autosomal recessive metabolic disorder resulting from an inborn error of metabolism. It causes renal tubular oxalosis which often leads to renal failure and early foetal demise. Only a few cases of PH detected in the neonatal period have been published in the literature.
Case report: This baby girl was the second child of a 30-year-old woman of a second-degree consanguineous marriage. Maternal gestational diabetes mellitus was diagnosed during the antenatal period. The baby was delivered at 37 weeks + 2 days of gestation following an emergency lower segment caesarean section due to the absence of liquor. A few hours after birth the baby developed respiratory distress and reduced urine output. Investigations revealed high serum creatinine levels. The ultrasound scan was suggestive of acute kidney injury and the baby died on day 2. There was no known family history of renal diseases. During the pathological autopsy examination, there were no definite dysmorphic features. The internal examination revealed bilateral lung hypoplasia and patent ductus arteriosus. The kidneys were of normal size and shape and the microscopy showed numerous, widespread, polarizable oxalate crystals within the renal tubules, in favour of primary hyperoxaluria.
Discussion and conclusion: The extensive renal damage imparted by oxalate deposition may have contributed to the impaired renal function and resulted in obstruction to the urine output, leading to oligohydramnios and pulmonary hypoplasia. Confirmation of the diagnosis of PH requires examination of urine and serum for high oxalate levels and detection of specific genetic mutations. Family screening and genetic counselling are necessary.