Ifosfamide-induced renal tubular dysfunction and rickets in children with Wilms tumor.

The renal tubular Fanconi syndrome developed in five patients with Wilms tumor after treatment with ifosfamide, a derivative of cyclophosphamide. Glomerular filtration rates were severely decreased. Renal function was investigated because of the development of rickets. All patients had undergone reduction of renal mass by nephrectomy. None had preexisting renal tubular injury. The syndrome developed at cumulative doses of ifosfamide of 39 to 99 gm/m2. Low serum bicarbonate and phosphate concentrations with glucosuria, aminoaciduria, and hypochloremic metabolic acidosis were the manifestations of the Fanconi syndrome. Bicarbonate and phosphate replacement resulted in bone healing, but recovery of tubular and glomerular function did not occur. Monitoring of these laboratory values during ifosfamide therapy could allow earlier replacement therapy to prevent severe bone disease.