A 55-year-old Caucasian male presents to the office for a routine check-up. He has no present complaints. His past medical history is significant for a long history of hypertension. He does not smoke or consume alcohol. His current medications are enalapril and hydrochlorothiazide. His blood pressure is 140/90 mm Hg and heart rate is 80/min. Physical examination reveals a moderately overweight man (BMI = 27 kg/m2) with a waist circumference of 41 inches. The laboratory studies show:
Which of the following is the most important pathogenic factor for this patient's condition?

Question

A 55-year-old Caucasian male presents to the office for a routine check-up.  He has no present complaints.  His past medical history is significant for a long history of hypertension.  He does not smoke or consume alcohol.  His current medications are enalapril and hydrochlorothiazide.  His blood pressure is 140/90 mm Hg and heart rate is 80/min.  Physical examination reveals a moderately overweight man (BMI = 27 kg/m2) with a waist circumference of 41 inches.  The laboratory studies show:
 Which of the following is the most important pathogenic factor for this patient's condition?

Quizplus · Accepted Answer

This vignette describes a patient with the typical clinical presentation of metabolic syndrome, which includes hypertension, impaired fasting glucose, and dyslipidemia. Patients are also characteristically overweight (as seen in this case), with predominantly central (abdominal) fat distribution that is reflected by an increased waist-to-hip ratio. Insulin resistance plays a central role in the pathogenesis of metabolic syndrome. Metabolic syndrome is diagnosed when at least 3 of the 5 following criteria are met: Abdominal obesity (Men: Waist circumference >40 inches; Women: Waist circumference >35 inches)Fasting glucose >100 - 110 mg/dLBlood pressure > 130/80 mm HgTriglycerides >150 mg/dLHDL cholesterol (Men: <40 mg/dL; Women: <50 mg/dL) Abdominal obesity (Men: Waist circumference >40 inches; Women: Waist circumference >35 inches) Fasting glucose >100 - 110 mg/dL Blood pressure > 130/80 mm Hg Triglycerides >150 mg/dL HDL cholesterol (Men: <40 mg/dL; Women: <50 mg/dL) (Choices A and B) Most health care providers believe that insulin resistance is the first event in the development of type 2 diabetes mellitus (DM); however, type 2 DM does not develop without a beta cell secretory defect. Increased insulin secretion from the beta cells is required to cope with increased insulin resistance. If beta cells are able to compensate for the increased insulin resistance, subjects generally remain normoglycemic at the expense of very high insulin levels; however, if beta cells are unable to compensate fully, glucose intolerance and type 2 DM results. (Choices D and E) Aside from problems with glucose control, insulin resistance is associated with several other systemic effects (e.g., dyslipidemia, endothelial dysfunction, procoagulable state, increased sympathetic activity, increased markers of inflammation, decreased uric acid excretion, increased sodium absorption, disordered breathing and increased testosterone production from the ovaries). Although sympathetic activity is increased in insulin resistance it does not play a central role in pathogenesis of metabolic syndrome. The endothelial dependent vasodilatation is impaired in insulin resistance. Educational Objective: Insulin resistance typical for patients with central-type obesity is the key pathogenic factor in the development of type-2 diabetes mellitus and associated abnormalities (hypertension, dyslipidemia). *Extremely high yield question for the USMLE!!!

A 55-Year-Old Caucasian Male Presents to the Office for a Routine