Diuretic-resistant Edema in a Child With Primary Coenzyme Q10 Deficiency and Nephrotic Syndrome: A Case Report

Background: Managing nephrotic syndrome in infancy can be challenging, especially when resistant to conventional treatments.This study reports a case with diuretic-resistant nephrotic syndrome and primary coenzyme Q10 (CoQ10) deficiency. Case Presentation:The case was a 22-month-old boy with diuretic-resistant edema, nephrotic syndrome, developmental delay, seizures, and multi-system involvement.Despite intensive interventions, including albumin and diuretic infusions, renin-angiotensin-aldosterone system inhibitors, and peritoneal dialysis, edema persisted.Initial suspicion of methylmalonic acidemia led to the administration of hydroxocobalamin.However, whole-exome sequencing revealed a homozygous pathogenic PDSS2 mutation, confirming primary CoQ10 deficiency, which led to the continuation of CoQ10 supplementation and discontinuation of methylmalonic acid (MMA) treatment.Unfortunately, the patient succumbed to sepsis before assessing the treatment response.Conclusions: This case highlights the diagnostic challenge of refractory nephrotic syndrome in infants and emphasizes the value of early genetic testing to identify rare but treatable conditions like CoQ10 deficiency.Timely diagnosis can enable targeted interventions and potentially improve outcomes.