A case of secondary oxalate nephropathy with nephrotic syndrome

Nephrotic syndrome, caused by various etiologies and pathophysiological mechanisms, is occasionally complicated by secondary oxalate nephropathy-a rare and often underrecognized condition associated with Chinese herbal medicine use. The co-occurrence of nephrotic syndrome and oxalate nephropathy is extremely uncommon, and delayed diagnosis may lead to severe outcomes.

A 19-year-old Chinese male presented with persistent edema for over 20 days and significant proteinuria. After taking traditional Chinese medicine for 20 days, his condition worsened rapidly, with new symptoms including infectious fever, erysipelas, acute renal failure, and heart failure.

The patient was diagnosed with nephrotic syndrome and acute oxalate nephropathy. Renal biopsy confirmed minimal change nephropathy (with possible focal segmental glomerulosclerosis) and acute tubulointerstitial injury with birefringent oxalate crystals in renal tubules.

A multidisciplinary treatment approach was adopted, including anti-infective therapy, volume expansion, diuresis, oral vitamin B6, methylprednisolone immunosuppression, and hemodialysis.

After one month of glucocorticoid therapy, hemodialysis, and supportive care, urine output increased and renal function improved. The patient was discharged without requiring further hemodialysis. Outpatient follow-up showed normalized renal function, resolved proteinuria, and normal renal ultrasonography.

Although traditional Chinese medicine is widely used in China, its potential to cause secondary oxalate nephropathy is often overlooked. Early renal biopsy is essential for accurate diagnosis and timely intervention in cases of nephrotic syndrome complicated by oxalate nephropathy.