Hypokalemic Distal Tubulopathy Secondary to Anti-Phospholipase A2 Receptor-Positive Membranous Nephropathy: An Exceptional Case.

INTRODUCTION: Primary membranous nephropathy, one of the most common primary nephrotic syndromes in adults, rarely has tubular involvement. Two case reports have previously illustrated atypical tubular manifestations, including Liddle-like syndrome and proximal tubulopathy. Hypokalemic distal tubulopathy in anti-phospholipase A2 receptor antibody-positive membranous nephropathy has not yet been recognized. CASE PRESENTATION: We report a case of a 37-year-old Thai male presenting with nephrotic syndrome and rhabdomyolysis secondary to severe hypokalemia. Kidney biopsy and serologic testing confirmed anti-phospholipase A2 receptor antibody-positive membranous nephropathy. Urinary indices showed a distal tubulopathy pattern. Hormonal studies, including plasma renin, plasma aldosterone, and a dexamethasone suppression test, were all negative. The patient responded well to prednisolone and oral cyclophosphamide. With nephrotic syndrome remission, hypokalemia was alleviated simultaneously. CONCLUSION: This case suggests a recognition and expansion of the knowledge of an extremely rare tubular involvement in relation to anti-phospholipase A2 receptor antibody-positive membranous nephropathy.