Nephrotic syndrome may be caused by primary (idiopathic) renal disease or by a variety of secondary causes. Patients present with marked edema, proteinuria, hypoalbuminemia, and often hyperlipidemia. In adults, diabetes mellitus is the most common secondary cause, and focal segmental glomerulosclerosis and membranous nephropathy are the most common primary causes. Venous thromboembolism is a possible complication; acute renal failure and serious bacterial infection are also possible, but much less common. There are no established guidelines on the diagnostic workup or management of nephrotic syndrome. Imaging studies are generally not needed, and blood tests should be used selectively to diagnose specific disorders rather than for a broad or unguided workup. Renal biopsy may be useful in some cases to confirm an underlying disease or to identify idiopathic disease that is more likely to respond to corticosteroids. Treatment of most patients should include fluid and sodium restriction, oral or intravenous diuretics, and angiotensin-converting enzyme inhibitors. Some adults with nephrotic syndrome may benefit from corticosteroid treatment, although research data are limited. Intravenous albumin, prophylactic antibiotics, and prophylactic anticoagulation are not currently recommended.