Osmotic nephrosis is the histopathologic counterpart of the syndrome known as colloid-induced kidney injury. It can be caused by a number of intravenous infusions commonly used in clinical medicine. Referring to an originally purported mechanism (osmotic injury) subsequently refuted, osmotic nephrosis is a misnomer. The actual mechanism (to an oversimplification) is the formation vacuoles containing the offending substance, in proximal tubular cells, via pinocytosis. Known causative agents include mannitol, IVIG and hydroxyethyl starch.
Excellent reviews can be found here and here. The first review addresses mainly the histopathologic changes and mechanisms of injury. The second review is relevant to the colloid versus crystalloid debate because it points out the potential renal toxicity of some colloid preparations.
Via Nephron Power.