Blue kidney in a pale patient-a case for a causal association between renal haemosiderosis in paroxysmal nocturnal haemoglobinuria and chronic kidney disease.

A 50-year-old man presented with pancytopenia and chronic renal impairment. He had evidence of intravascular haemolysis. The direct antiglobulin (Coomb's) test was negative. Paroxysmal nocturnal haemoglobinuria (PNH) was diagnosed by the Ham acid haemolysis test. There were no other clinical risk factors that could be implicated in chronic kidney disease (CKD). A renal biopsy revealed extensive haemosiderosis affecting proximal tubular cells and associated interstitial fibrosis as well as tubular atrophy. No glomerular or vascular lesions were seen. These findings strengthen the case for a causal relationship between renal haemosiderosis in PNH and CKD.