Nephrotic-range proteinuria and brown urine in an 8-year-old girl: Answers

No glomerular lesions with hematoxylin and eosin staining (a) and periodic acid Schiff (PAS) staining (b), with an excess of tubular iron deposits on Perls’ Prussian blue staining (c).

The current diagnostic criteria of Henoch–Schönlein purpura (HSP) include vascular purpura associated with at least one of the following: abdominal pain, leukocytoclastic vasculitis with Immunoglobulin A (IgA) deposits on skin biopsy, acute arthritis or arthralgia, and renal injury confirmed by proteinuria and/or hematuria [1]. Although our patient fulfills the above criteria, concomitant hemolytic anemia and tubular iron deposits make the diagnosis of Henoch-Schönlein Purpura (HSP) highly doubtful. Glomerular immunofluorescence is the examination of choice to confirm our assumption. In our patient, no mesangial IgA deposits were found and HSP was excluded. All diseases triggering intravascular hemolysis may provoke renal injury and secondary tubular iron deposits. Autoimmune and microangiopathic hemoglobinuria are excluded by the first laboratory investigation. Malaria and drug-induced hemoglobinuria are highly unlikely as no history of travel in endemic regions or previous medication was noted. Paroxysmal nocturnal hemoglobinuria (PNH) and cold hemoglobinuria are thus the most probable diagnoses. Detection of PNH clone at 89% with flow cytometry permitted us to establish a diagnosis of PNH.

Urinary cytology: urinary dipstick is a highly sensitive examination for heme detection [2]. On the other hand, urinary erythrocyte count in a urinary cytology examination helps to distinguish hematuria from other causes of brown urine, including hemoglobinuria and myoglobinuria [2]. As expected, our patient presented with a positive urinary dipstick, but a normal urinary erythrocyte count level (<10,000/mm³).