In idiopathic thrombocytopenic purpura, intravenous immunoglobulin the
rapy is currently a treatment of choice. It is usually effective with
little side-effects. Acute renal failure has been recently identified
as a potential, though rare, complication of intravenous immunoglobuli
ns. However, the mechanism remains unclear. A 53 year-old-woman with i
diopathic thrombocytopenic purpura developed oliguric renal failure af
ter high doses of intravenous immunoglobulins. Her renal function retu
rned to normal after dialysis and plasmapheresis. This rapid normaliza
tion suggested that acute renal failure was functional. Since laborato
ry tests showed an increase in protidemia concomitant to the immunoglo
bulin therapy, acute renal failure was likely to be related to hyperos
molar renal damage.