Fanconi syndrome and CKD in a patient with paroxysmal nocturnal hemoglobinuria and hemosiderosis

Fanconi syndrome and chronic kidney disease associated with paroxysmal nocturnal hemoglobinuria is rarely reported. We describe a 51-year-old woman with glomerular filtration rate decrease and hypokalemia, glucosuria, and proteinuria during a 4-year period. Paroxysmal nocturnal hemoglobinuria was diagnosed 17 years earlier, and she has received multiple blood transfusions because of hemolytic episodes during the last 5 years. Deteriorating kidney function and persistent Fanconi syndrome were accompanied by a progressive increase in serum ferritin levels. Laboratory studies showed proximal renal tubular acidosis, hypophosphotemic hyperphosphaturia, normoglycemic glucosuria, and aminoaciduria. Serologic testing, tumor markers, Bence-Jones protein, and heavy-metal screening results were negative. Abdominal magnetic resonance imaging showed characteristic features of iron deposition in the bilateral renal cortices. Kidney biopsy showed chronic interstitial nephritis with prominent hemosiderin deposition in the proximal tubules. With potassium citrate, calcitriol, and deferoxamine therapy, Fanconi syndrome persisted, but kidney function was stable. Renal hemosiderosis secondary to both chronic repetitive hemolytic episodes and transfusion-related iron overload in patients with paroxysmal nocturnal hemoglobinuria can lead to Fanconi syndrome and chronic kidney disease.