Unsuitability of electron microscopic examination of urinary sediment for the diagnosis of amyloidosis.

Several recent reports suggest that amyloidosis can be diagnosed by ultrastructural identification of fibrillar proteins in the urinary sediment. However, the authors routinely identified similar fibrils in the urinary sediments of all patients with a wide variety of renal diseases who were producing urinary casts, as well as in those of stressed healthy individuals. They therefore conclude that electron microscopic examination of the urinary sediment alone has little value in the diagnosis of amyloidosis when unaccompanied by chemical or immunologic tests.