Membranous Nephropathy Associated With an Over-the-Counter Supplement

Membranous nephropathy (MN) is a frequent cause of nephrotic syndrome that can result in ongoing proteinuria, elevated serum creatinine, and declining kidney function. Neural epidermal growth factor-like 1 (NELL1) is a target antigen in MN. Alpha-lipoic acid (ALA) is an over-the-counter antioxidant frequently used for neuropathic pain and may be a potential trigger for NELL1-associated MN (NELL1-MN). A 56-year-old female was seen for recent onset of acute lower extremity swelling and frothy urine. Proteinuria was identified on urinalysis. Laboratory evaluation showed an abnormally high urine protein/creatinine ratio with a normal serum creatinine. Renal biopsy confirmed NELL1-MN. The patient reported taking a dietary supplement containing 600 mg of ALA daily for neuropathy over the preceding three months. The ALA supplement was discontinued, and the patient was monitored closely with labs. At the five-month follow-up, the patient noted improvement in edema, and repeat laboratory evaluations demonstrated complete resolution of proteinuria. This case suggests that ALA-associated NELL1-MN may be reversible. Once ALA was identified and discontinued, significant improvement occurred without the need for immunosuppression.