From recurrent flank pain to systemic oxalosis: a case of primary hyperoxaluria type 1 requiring dual organ transplantation.

INTRODUCTION AND IMPORTANCE: Primary hyperoxalurias (PH) are rare autosomal recessive inherited disorders that disrupt the metabolism of glyoxylate and oxalate. The most common type, primary hyperoxaluria type 1 (PH1), is caused by a deficiency in the liver enzyme alanine-glyoxylate aminotransferase (AGT), leading to the overproduction and excessive urinary excretion of oxalate.

CASE PRESENTATION: On routine evaluation, the patient presented with deranged renal function and echogenic kidneys. Imaging via KUB X-ray revealed radio-opaque kidney stones, small shrunken kidneys, and nephrocalcinosis, indicating progression to end-stage kidney disease (ESKD). Additional systemic manifestations included increased lumbar bone density and pulmonary fibrosis. Diagnosis was definitively confirmed through elevated 24-hour urinary oxalate levels and genetic screening showing an AGXT gene mutation. This necessitated combined liver-kidney transplantation (CLKT): the liver graft provides the missing AGT enzyme to stop oxalate production, while the kidney graft replaces damaged organs and discontinues chronic dialysis.

CLINICAL DISCUSSION: PH1 must be suspected in pediatric patients presenting with recurrent urolithiasis or nephrocalcinosis, especially in clinical cases of consanguinity. Early interventions - high fluid intake, crystallization inhibitors, and pyridoxine - can help preserve kidney function. For patients reaching ESKD, combined transplantation is the most effective approach to correct the underlying metabolic error and stop oxalate accumulation.

CONCLUSION: This case highlights the diagnostic challenge of PH1, where the initial presentation with flank pain and urinary symptoms may mimic a urinary tract infection, placing the patient at potential risk of urosepsis if misdiagnosed or untreated. CLKT remains the definitive treatment in advanced disease.