Metabolic syndrome is a cluster of common abnormalities, including insulin resistance, impaired glucose tolerance, abdominal obesity, reduced high-density lipoprotein (HDL)-cholesterol levels, elevated triglycerides, and hypertension.
Incidence is increasing in line with the number of people who are overweight or obese, with one quarter of the Western population estimated to have the condition.
Multiple criteria exist to define metabolic syndrome.
Increases risk of cardiovascular disease and diabetes, although there are ethnic variations in the incidence of comorbidities associated with metabolic syndrome defined by the same criteria.
The precise pathogenetic mechanisms unifying all of its components are as yet unknown, although insulin resistance certainly plays a key role.
Obesity, an atherogenic diet, and physical inactivity are the strongest risk factors for the development of metabolic syndrome.
Lifestyle interventions, including a diet low in saturated fats and moderate to intense physical activity, are the mainstay of treatment.
A multifactorial approach targeting low-density lipoprotein (LDL)-cholesterol and non-HDL-cholesterol levels, blood pressure control, and glucose reduction is recommended.
Statins are considered first-line treatment when lifestyle measures do not achieve the desired non-HDL-cholesterol levels. Fibrates also play a significant role in the modification of lipid levels.
Metabolic syndrome, originally described by Reaven in 1988 as "syndrome X" or "insulin resistance syndrome", is a cluster of common abnormalities, including insulin resistance, impaired glucose tolerance, abdominal obesity, reduced high-density lipoprotein (HDL)-cholesterol levels, elevated triglycerides, and hypertension. No known common cause unifies its components. The condition reflects the sedentary lifestyle, overnutrition, and resultant excess adiposity of the modern world. Metabolic syndrome is associated with endothelial dysfunction and atherosclerosis resulting in an increased risk of cardiovascular disease (CVD) and type 2 diabetes mellitus. The main utility of diagnosing metabolic syndrome is the identification of people at high risk of CVD beyond low-density lipoprotein (LDL)-cholesterol levels. However, whether a diagnosis of metabolic syndrome provides more useful information than its individual components regarding cardiovascular risk is greatly controversial.
History and exam
Key diagnostic factors
- presence of risk factors
- increased BMI
- increased waist and hip circumferences
Other diagnostic factors
- type 2 diabetes mellitus (DM)
- non-alcoholic fatty liver disease
- sleep disturbance, excessive daytime sleepiness, snoring, gasping breaths
- menstrual disturbances
- abdominal pain
- corneal arcus and xanthelasma
- acanthosis nigricans
- insulin resistance
- physical inactivity
- high-saturated-fat diet
- high-carbohydrate diet
- excess alcohol consumption
- increasing age
- positive family history
- polycystic ovary syndrome (PCOS)
- HIV infection
1st investigations to order
- fasting blood glucose
- fasting triglycerides
- fasting total cholesterol
- fasting HDL-cholesterol
- fasting LDL-cholesterol
Investigations to consider
- oral glucose tolerance test (OGTT)
- serum urea and creatinine
- thyroid-stimulating hormone (TSH)
- free T4
- abdominal ultrasound
- serum total and free testosterone
- serum dehydroepiandrosterone sulfate
- serum sex hormone binding globulin
- serum luteinising and follicle-stimulating hormones
- ultrasound of ovaries
- serum uric acid
Panagiotis Anagnostis, MD, PhD
Department of Internal Medicine
Aristotle University of Thessaloniki
PA declares that he has no competing interests.
Dr Panagiotis Anagnostis would like to gratefully acknowledge Professor Faidon Harsoulis, a previous contributor to this topic.
FH declared that he had no competing interests.
Kent Wehmeier, MD
Division of Endocrinology
Division of Endocrinology, Diabetes and Metabolism
University of Florida College of Medicine
KW declares that he has no competing interests.
Scott Grundy, MD, PhD
Center for Human Nutrition
The University of Texas Southwestern Medical Center
SG is an author of several references cited in this topic. SG has consulted for several companies (Pfizer, AstraZeneca, Merck, Merck Schering Plough, Lilly, Abbott, Sanofi-Aventis, GlaxoSmithKline) that produce lipid-lowering drugs.
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