Osmotic Nephropathy Induced by L-Proline Stabilized Sucrose-free Intravenous Immunoglobulins: A Case Report

Acute kidney injury following sucrose-free intravenous immunoglobulins (IVIG) is rare. We report the case of a 67-year-old male who developed a sudden anuric acute kidney injury at day 4 of L-proline stabilized sucrose-free IVIG for a Guillain-Barré Syndrome. The IVIG treatment was halted. The patient did not require renal replacement therapy after an adequate response to diuretics. Amoxicillin was the sole other potential nephrotoxic. The kidney biopsy showed typical features of osmotic nephropathy (ON). Although a certain degree of kidney hypoxia due to dysautonomia and variations of blood pressure might have occurred, histological findings were not compatible with an ischemic acute tubular necrosis. There was no glomerular and vascular involvement. Immunofluorescence of tubular cells cytoplasm was negative, ruling out antibody deposition. The patient had a complete renal recovery after 2 weeks. We hypothesize that proline itself acted as a reabsorbed toxic solute and accumulated in the lysosomes, leading to ON. In this case report we discuss the proline proximal tubular transport, involving pinocytosis in case of high concentration in the filtrate, and potential mechanisms involved in the development of ON.