Metabolic Syndrome
Chapter 12
Definitions
• Metabolic syndrome
• Collection of interrelated cardiometabolic risk factors that are present in a
given individual more frequently than may be expected from a chance
combination
• Usually in the presence of overweight or obesity
• Greater risk for developing atherosclerotic cardiovascular disease (ASCVD)
• First observed – 1923
• Hypertension, hyperglycemia, hyperuricemia
• Term first used – 1977
• Combination of dx a significant risk of arteriosclerosis due to cluster.
Scope
• Prevalence of metabolic syndrome
Almost 34.3%, based on NHANES 2011-2012 data and ATP III criteria
• Normal-weight obesity (Normal range BMI)
• Abdominal obesity
• Strongly associated with increased risk for cardiovascular mortality
• Diabetes
• Metabolically healthy obese
• High BMI but normal cardiometabolic health
• None of the diagnoses for MetS
Definitions
• Metabolic Syndrome
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Obesity,
Diabetes
Hyperlipoproteinemia – form of dyslipidemia
Hyperuricemia – increased uric acid
Hepatic steatosis – fatty liver disease
• 2009 – definitions
• Table 12.1
Definitions
• Metabolic syndrome – 3 or more conditions
• Abdominal obesity
• Elevated waist circumference
• Elevated triglycerides
• >150 mg/dl
• Reduced HDLc
• Men < 40 mg/dl
• Women < 50 mg/dl
• Elevated blood pressure
• >130/85 mmHg
• Elevated fasting glucose
• >100 mg/dl
Scope
• Metabolic syndrome and the aging adult
Prevalence increases with age and peaks around age 60 years
• Pediatric metabolic syndrome
~42% aged 12 to 19 years present with one or more metabolic abnormalities
• Economic burden
60% greater health care cost for those with metabolic syndrome
• Obesity leads to more chronic disorders than smoking!
NHANES 2003-2006
• Gender and ethnic diversities
• Hispanic Americans highest risk (35.4%)
• Non-Hispanic Whites (33.4%)
• African Americans (32.7%)
Pediatric MetS
• NHANES 2001-2006:
• 10% of 12-19 year old
• 3 or more
• Lack of norms for CVD risk factors
• > 95th percentile – growth charts
• Labeled obese
• 85-95th percentile
• Labeled overweight
Pathophysiology
• Characterized by a co-occurrence of
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Atherogenic dyslipidemia
HTN
Elevated glucose
Chronic low-grade inflammation
Prothrombosis
Mitochondrial dysfunction
• Widely thought to occur as a result of
• Obesity (specifically android obesity)
• Insulin resistance
Pathophysiology
• Previous conditions lead to
• Diabetes
• Atherosclerotic cardiovascular disease (ASCVD)
• But –
• These conditions do not always lead to MetS
Components of Metabolic Syndrome
Pathophysiology
• MetS may be “premorbid” condition
• Insulin resistance
• Takes years to develop
• Need to identify at risk individuals
• Failure of insulin to maintain glucose homeostasis
• Insulin receptor
• Insulin signaling
• Evidence of systemic inflammation, oxidative stress and endothelial
dysfunction is occurring in MetS
Non-alcoholic Fatty Liver-Steatosis
Pathophysiology
• Obesity and Ectopic Adiposity
• Accumulation of fat in non-adipose tissue
• Obesity – independent risk factor for
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Insulin resistance
Hyperglycemia
Dyslipidemia
Hypertension
• Untreated
• Increased risk for chronic disease
• Early all-cause mortality
Pathophysiology
• Visceral adipose tissue (VAT)
• AKA ectopic
• Fat accumulates in non-adipose
areas
• Lipotoxic
• Disequilibrium between energy
intake and expenditure
• Skeletal muscle insulin resistance
Pathophysiology
• Mitochondrial dysfunction – decreased:
• Size
• Density
• Function
• Decreased ATP production
• Decreased functional capacity
• Energy deficit
• Sedentary behavior – strong predictor of mitochondrial dysfunction
Pathophysiology
• Inflammation
• Ectopic adiposity increases proinflammatory cytokines
• Tumor necrosis factor-alpha
• Interleukin-6
• Excess amounts
• Triglycerides and cholesterol
• Interferes with insulin signaling
• Leads to cellular oxidative stress
Clinical Considerations
• Research continues to vary in definition of MetS
• General findings
• Increased cardiovascular events
• ASCVD risk significantly higher
• Increase in all cause mortality
Clinical Considerations
• Signs and symptoms
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Elevated fasting glucose
Hypertension
Elevated triglyceride levels
Low high-density lipoprotein cholesterol level
Abdominal obesity
Microalbuminuria
Hyperuricemia
Fatty liver disease
Clinical Considerations
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Signs and symptoms (cont)
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High levels of PAI-1 and fibrinogen (i.e., prothrombotic state)
Elevated high-sensitivity C-reactive protein (hsCRP) (i.e.,
proinflammatory state)
Cholesterol gallstones
Polycystic ovary syndrome
Disordered sleeping (e.g., sleep apnea)
History and Physical
• Identify the core risk components of metabolic syndrome.
• 3 or more – increased risk
• 1 or 2 – less risk of CVD
• Monitor abdominal obesity.
• Obtain clinical measure of waist circumference
History and Physical
• Appropriate risk assessment for patients diagnosed with metabolic
syndrome should be based on the presence of
• Dysglycemia
• Impaired fasting glucose
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Hypertension
Elevated triglyceride levels
Low HDL
Central obesity or high BMI
Exercise Testing
• According to ACSM, test not required to begin low- to moderateintensity exercise program
• If test performed
• Use standardized treadmill protocol
• Low initial workload
• Increase with small increments
Exercise Testing
• Standardized treadmill protocols that use:
• Relatively small workload increases
• 5 METs or less
• Bruce Low Level Protocol (3 min stages)
• Stage 1
1.2 mph/0% grade/2 METs
Stage 2
1.2 mph/3% grade/2.5 METs
Stage 3
1.2 mph/6% grade/3 METs
Stage 4
1.7 mph/6% grade/3.5 METs
Treatment
• Interventions – reduce risk for ASCVD
• Weight loss
• Caloric restriction
• Increased physical activity
• Pharmacologic agents
• Surgical procedures
• Behavioral modifications
• Improvements in diet quality
• Participation in physical activity
• Similar guidelines to those with obesity or diabetes
• Smoking cessation (nicotine -> hypertension)
• Not a criteria for MetS
Exercise Prescription
• Cardiovascular exercise
• 150 to 250 min of moderate-intensity PA per week,
• Energy equivalent of 1,200 to 2,000 kcal
• Continuous or intermittent low intensity (40-60% VO2 or HRR)
• To moderate intensity (50% to 75% VO2 or HRR)
• Sessions should be 30 to 60 min in duration (minimum of 10
min for intermittent cardiovascular exercise)
• Gradual progression in duration and intensity may be effective
for chronic weight maintenance
Exercise Prescription
• Resistance exercise
• No recommendations at present
• Current minimums suggested
• 2 to 3 d/wk
• Single set of 5 to 10 exercises for whole body
• Moderate intensity – 10-15 reps
• Range of motion exercises
• Stretching when warmed up
• Include all major muscle groups
• May need static stretching to begin
• Hold stretch 15-60s
Exercise Prescription
Conclusions
• Diagnosis of the metabolic syndrome requires presence of three or
more of the following risk factors:
• (1) elevated waist circumference,
• (2) elevated triglycerides,
• (3) reduced HDL cholesterol,
• (4) elevated blood pressure, and
• (5) elevated fasting glucose.
Conclusions
• When combined with dietary interventions
• Cardiovascular exercise best means for weight loss
• Recommended – 10% reduction
• Aerobic exercise improves mitochondrial function
• Increase in size
• Increase in number