Evaluation of proteinuria.

Proteinuria, a common finding on urinalysis, may indicate the presence of a wide variety of medical conditions, some of which are benign and associated with a favorable prognosis (such as orthostatic proteinuria) and others of which have more serious implications (such as glomerular disease or multiple myeloma). The amount of protein excreted in the urine may be increased by several factors, including increases in glomerular hydraulic pressure, pathologic changes of the glomeruli, decreases in tubular reabsorption and catabolism of protein, and increases in production or concentration of plasma proteins normally filtered by the glomerulus. Because proteinuria may reflect a severe renal pathologic condition, further evaluation should be undertaken to determine the most likely cause of the proteinuria.