Endocrinology · Metabolic Disorders
The facts most likely to be tested
Metabolic syndrome is defined by the presence of at least three of five criteria: abdominal obesity, hypertriglyceridemia, low HDL cholesterol, hypertension, and elevated fasting glucose.
Abdominal obesity is defined by a waist circumference of ≥40 inches in men or ≥35 inches in women.
Hypertriglyceridemia is defined as serum triglycerides ≥150 mg/dL or the use of medication to treat elevated triglycerides.
Low HDL cholesterol is defined as <40 mg/dL in men or <50 mg/dL in women, or the use of medication to treat low HDL.
Hypertension is defined as blood pressure ≥130/85 mmHg or the use of antihypertensive medication.
Elevated fasting glucose is defined as ≥100 mg/dL or a previous diagnosis of type 2 diabetes mellitus.
The primary pathophysiologic mechanism underlying metabolic syndrome is insulin resistance driven by adipose tissue dysfunction.
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A 48-year-old male presents for a routine physical. He has a waist circumference of 42 inches, a blood pressure of 138/88 mmHg, and a fasting plasma glucose of 108 mg/dL. Laboratory studies reveal a triglyceride level of 165 mg/dL and an HDL cholesterol of 38 mg/dL. He has no history of diabetes or cardiovascular disease.
Which of the following is the most appropriate initial management for this patient?
Lifestyle modification with diet and exercise
The patient meets all five criteria for metabolic syndrome; the first-line treatment for metabolic syndrome is aggressive lifestyle modification to address the underlying insulin resistance.
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Etiology / Epidemiology
Driven by insulin resistance and central obesity. Highly prevalent in patients with sedentary lifestyle and high-calorie intake.
Clinical Manifestations
Often asymptomatic; look for android obesity and acanthosis nigricans. Physical exam reveals waist circumference >40 in (men) / >35 in (women).
Diagnosis
Requires 3 of 5 criteria: BP ≥130/85, TG ≥150, HDL <40 (men)/<50 (women), Fasting Glucose ≥100, and Waist Circumference.
Treatment
Primary goal is lifestyle modification (diet/exercise). Use metformin for glycemic control and statins for lipid management.
Prognosis
Increases risk of Type 2 Diabetes and Atherosclerotic Cardiovascular Disease (ASCVD) by 2-5 fold.
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Epidemiology & Etiology
Metabolic syndrome is a cluster of metabolic abnormalities that significantly increase cardiovascular risk. It is primarily driven by insulin resistance associated with visceral adiposity. Prevalence increases with age, ethnicity, and socioeconomic factors contributing to a metabolic triad of obesity, hypertension, and dyslipidemia.
Pertinent Anatomy
The primary anatomical focus is visceral adipose tissue (intra-abdominal fat). This tissue is metabolically active, releasing free fatty acids directly into the portal circulation, which impairs hepatic insulin sensitivity.
Pathophysiology
Insulin resistance leads to compensatory hyperinsulinemia, which initially maintains euglycemia but eventually fails. Increased free fatty acids promote hepatic gluconeogenesis and VLDL production, while decreasing HDL synthesis. This state creates a pro-inflammatory and pro-thrombotic state that accelerates atherogenesis.
Clinical Manifestations
Patients are frequently asymptomatic until complications arise. Look for acanthosis nigricans as a cutaneous marker of insulin resistance. Red flags include symptoms of undiagnosed diabetes (polyuria, polydipsia) or signs of end-organ damage like hypertensive retinopathy or claudication.
Diagnosis
Diagnosis is based on the NCEP ATP III criteria. A patient must meet 3 of 5 specific thresholds: Waist circumference >102cm (men) / >88cm (women), TG ≥150 mg/dL, HDL <40 mg/dL (men) / <50 mg/dL (women), BP ≥130/85 mmHg, and Fasting glucose ≥100 mg/dL.
Treatment
The cornerstone is lifestyle modification focusing on a 5-10% weight loss and 150 minutes of moderate-intensity exercise weekly. Pharmacotherapy is directed at individual components: statins for dyslipidemia and metformin for glucose intolerance. Avoid thiazolidinediones in patients with Class III/IV heart failure.
Prognosis
Patients face a 5-fold increase in the risk of developing Type 2 Diabetes Mellitus. Long-term management requires aggressive monitoring of HbA1c and ASCVD risk scores to prevent myocardial infarction and stroke.
Differential Diagnosis
Cushing Syndrome: presence of moon facies, buffalo hump, and striae
Polycystic Ovary Syndrome: associated with hirsutism and irregular menses
Hypothyroidism: check TSH to rule out metabolic slowing
Lipodystrophy: rare genetic fat distribution disorders
Type 2 Diabetes: distinguished by fasting glucose ≥126 mg/dL