The role of the laboratory in the diagnosis of the metabolic syndrome.

The metabolic syndrome is now an accepted disorder and has a code in the International Classification of Diseases, Ninth Revision (277.7). It afflicts approximately 1 in 4 American adults. The features of the metabolic syndrome include abdominal obesity and atherogenic dyslipidemia manifesting as elevated levels of triglycerides, low levels of high-density lipoprotein cholesterol (HDL-C), and a preponderance of small, dense low-density lipoprotein (LDL) particles.1–3 Other features include increased blood pressure, insulin resistance and/or glucose tolerance, and prothrombotic and proinflammatory diathesis. The laboratory has a critical role in the diagnosis of the metabolic syndrome because of the 5 features; 3 are laboratory-based, including triglyceride levels of 150 mg/dL (1.7 mmol/L) or more; HDL-C levels less than 40 mg/dL (1.0 mmol/L) and 50 mg/dL (1.3 mmol/L) in men and women, respectively; and fasting plasma glucose levels of 100 mg/dL (5.6 mmol/L) or more. The importance of the metabolic syndrome is that it confers at least a 2-fold risk of cardiovascular disease and at least a 5-fold increased risk for subsequent diabetes.1–3 In addition, it is not uncommon for patients with metabolic syndrome to have nonalcoholic steatohepatitis, generally diagnosed by increased transaminase levels with an alanine aminotransferase/aspartate aminotransferase ratio of more …