Dietary Oxalate Nephropathy Due to Pureed Feeds

An 8-year-old boy with a 5q14.3 deletion presented with an elevated serum creatinine level of 1.8 mg/dL. A kidney biopsy demonstrated tubular injury and extensive oxalate crystals. His serum and urinary oxalate levels were elevated, but genetic testing for primary hyperoxaluria was negative. The patient depended on pureed foods for nutrition, and his mother consistently used a large amount of spinach and nuts when preparing his blenderized feeds. Hence, his dietary intake of oxalate was extremely high. After dietary modification, his serum and urinary oxalate levels decreased, but his serum creatinine levels had increased to 2.1 mg/dL. Unfortunately, the reported outcome of secondary oxalate nephropathy is poor, with no patients having a full recovery and the majority developing kidney failure. Children on pureed foods are at risk of hyperoxaluria if there is a chronic high intake of foods with elevated oxalate content, and caregivers may not realize that healthy foods such as spinach and nuts are high in oxalate. Nutritional counseling of children on pureed foods should include screening for excessive oxalate intake, especially if there is a decrease in kidney function or kidney stones.