Diagnostic Studies
Laboratory Tests. Most patients over age 50 with leg edema have venous insufficiency, but if the etiology is unclear, a short list of laboratory tests will help rule out systemic disease: complete blood count, urinalysis, electrolytes, creatinine, blood sugar, thyroid-stimulating hormone, and albumin. A serum albumin below 2 g/dL often leads to edema and can be caused by liver disease, nephrotic syndrome, or protein-losing enteropathy.[14] Additional tests are indicated depending on the clinical presentation:
Patients who may have a cardiac etiology should have an electrocardiogram, echocardiogram, and chest radiograph. Dyspneic patients should have a brain natriuretic peptide (BNP) determination to help detect heart failure. The BNP is most helpful for ruling out (rather than ruling in) heart failure because the sensitivity is high (90%).[23]
Idiopathic edema can be diagnosed in young women without further testing if there is no reason to suspect another etiology based on history and physical examination.[5] However, tests to confirm idiopathic edema have been described and may be helpful in difficult cases ( Table 5 ).[12,24]
In patients with acute edema (