[Renal failure and rickets].

Area of Science:

• Pediatric Nephrology
• Clinical Pharmacology
• Endocrinology

Background:

• Diphenylhydantoin (phenytoin) is an anticonvulsant medication.
• Previous reports link sodium diphenylhydantoins to interstitial nephritis and vitamin D metabolism interference, potentially causing or worsening rickets.
• Vitamin D deficiency rickets can manifest with seizures due to hypocalcemia.

Observation:

• An infant presented with seizures, diagnosed with renal failure and rickets.
• The infant had a history of convulsions treated with diphenylhydantoins for four months.
• Renal biopsy confirmed interstitial nephritis.

Findings:

• The infant's seizures were attributed to hypocalcemic tetany, misdiagnosed as epilepsy and treated with diphenylhydantoins.
• Interstitial nephritis complicated by acute renal failure was likely induced by diphenylhydantoins.
• Treatment with dehydrotachysterol led to clinical and radiological improvement of rickets, with gradual recovery of renal function.

Implications:

• This case highlights the potential nephrotoxic and endocrine-disrupting effects of diphenylhydantoins in infants.
• It underscores the importance of considering drug-induced conditions in the differential diagnosis of pediatric renal failure and rickets.
• Accurate diagnosis and appropriate management, including vitamin D repletion and withdrawal of the offending drug, are crucial for favorable outcomes.