Understanding Obesity and Its Assessment

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Questions and Answers

Which factor is NOT considered an environmental cause of obesity?

Sedentary lifestyle

Genetic predisposition (correct)

High-calorie food consumption

Large portion sizes

What percentile indicates a child is classified as underweight?

Less than 10th percentile

Less than 2nd percentile

Less than 5th percentile (correct)

Between 5th and 15th percentile

What is the percentage range of heritability of BMI based on studies?

60% to 80%

70% to 90%

40% to 70% (correct)

20% to 40%

In clinical practice, which assessment is used for children and adolescents between the ages of 2–20 for obesity?

Body mass index (BMI) percentile Signup and view all the answers

Which class of obesity is defined as a BMI greater than 40 kg/m²?

Class 3 obesity Signup and view all the answers

Monogenic obesity is typically linked to mutations in which pathway?

Leptin-melanocortin pathway Signup and view all the answers

What characteristic is often associated with obesity-related low-grade systemic inflammation?

Excessive secretion of proinflammatory adipokines Signup and view all the answers

Which of the following is NOT a commonly cited psychosocial impact of obesity?

Increased self-esteem Signup and view all the answers

What characteristic is typically associated with primary obesity?

Increased nutritional intake and decreased physical activity Signup and view all the answers

Which of the following endocrine disorders is associated with secondary obesity?

Hypothyroidism Signup and view all the answers

What is a common genetic variant associated with monogenic obesity?

MC4R Signup and view all the answers

What key factor is assessed when evaluating childhood obesity?

Height and weight considering BMI Signup and view all the answers

Which psychosocial impact is commonly observed in children with obesity?

Food-seeking behavior Signup and view all the answers

What is likely to indicate an endocrine cause in a child with obesity?

Short stature and decreased height velocity Signup and view all the answers

Which of the following medications is known to contribute to obesity?

Antipsychotic drugs Signup and view all the answers

Which statement regarding lipid intermediates and insulin resistance is true?

They contribute to impaired insulin signaling. Signup and view all the answers

Which of the following skin findings is commonly associated with insulin resistance?

Acanthosis nigricans Signup and view all the answers

Which sign is NOT associated with syndromic obesity?

Hyperactivity Signup and view all the answers

What is one of the recommended first steps to assess for glycemic dysregulation in children?

Fasting blood glucose test Signup and view all the answers

Which of the following conditions is suggested by severe acne and hirsutism in pubertal girls?

Polycystic ovary disease Signup and view all the answers

Which obesity-associated comorbidity may present with right upper quadrant tenderness?

Hepatomegaly Signup and view all the answers

What test is suggested if liver function tests are elevated in a child?

Liver imaging Signup and view all the answers

Which of the following features is characteristic of Bardet-Biedl syndrome?

High-arched palate Signup and view all the answers

Which test would be appropriate for children exhibiting symptoms of disrupted sleep cycles and hyperactivity?

Sleep study Signup and view all the answers

Study Notes

Obesity Definition

Obesity is an excess of body fat.
It's estimated by the relationship between height and weight, considering age and sex.

Assessing Obesity

Growth charts from the CDC or WHO are used to assess obesity.
For children under 2 years old:
- Weight percentiles and weight-for-length charts are used.
For children and adolescents ages 2-20:
- Body mass index (BMI) percentile is used.
For children and adolescents ages 2-20 with BMIs greater than the 95th percentile:
- Percent of the 95th percentile is used.

Obesity Categories

Underweight: less than the 5th percentile
Healthy weight: 5th to 84th percentile
Overweight: 85th to 94th percentile
Class 1 obesity: 95th percentile to 119% of the 95th percentile
Class 2 obesity: 120% to 139% of the 95th percentile or a BMI greater than 35 kg/m2 and less than 39 kg/m2
Class 3 obesity: greater than 140% of the 95th percentile or a BMI greater than 40 kg/m2

Pathophysiology of Obesity

Environmental Factors:
- High-calorie food supplies
- Large portion sizes
- Increased sedentary activities
- Decreased time spent in physical activities
- Television watching
- Use of electronic devices
Genetic Factors:
- BMI heritability is estimated at 40%-70% based on studies.
- Single-gene mutation (monogenic) obesity is rare.
- Most single-gene mutations are connected to the leptin-melanocortin pathway.

Pathogenesis of Complications

Adipocytes synthesize adipokines and hormones, which are affected by the amount and distribution of adipose tissue.
Excess proinflammatory adipokines from adipocytes and macrophages within adipose tissue cause a low-grade systemic inflammatory state in obese individuals.
Elevated levels of free fatty acids, inflammatory cytokines, and lipid intermediates in nonadipose tissues contribute to impaired insulin signaling and insulin resistance.

Etiological Classification

Primary Obesity (Exogenous or Simple Obesity):
- Caused by unhealthy diet and lack of physical activity.
- Results in increased or consistent linear growth.
- Precocious puberty can occur.
Secondary Obesity:
- Endocrinopathies:
  - Hypothalamic/pituitary dysfunction (with growth hormone deficiency)
  - Hypercortisolism (Cushingoid features, consider a dexamethasone suppression test or 24-hour urinary free cortisol)
  - Hypothyroidism (check thyroid-stimulating hormone [TSH], free thyroxine [T4] test)
  - Pseudohypoparathyroidism
  - Neonatal hyperinsulinemia
- Genetic syndromes:
  - Down syndrome
  - Beckwith-Wiedemann syndrome
  - Accompanied by other behavior, functional, or anatomic abnormalities.
- Monogenic Obesity:
  - Affects a minority of children with obesity.
  - Alterations in a single gene lead to early-onset severe obesity.
  - Common mutation: MC4R (melanocortin 4 receptor).
  - Other forms: Leptin deficiency, leptin receptor variants, and POMC (pro-opiomelanocortin) mutation
  - May be associated with syndromes like Prader-Willi or Bardet-Biedl.
- Medications:
  - Antipsychotic drugs
  - Glucocorticoids

Clinical Picture of Childhood Obesity

Height and weight:
- Calculate BMI from weight and height, plot on appropriate growth chart.
- Compare weight gain with height gain.
- Normal or increased height and height velocity in exogenous obesity.
- Short stature and decreased height velocity suggest possible endocrine cause.
- Waist circumference at the level of the iliac crest.
  - Central obesity more commonly seen in Cushing syndrome.
Vital signs:
- Eg., bradycardia in hypothyroidism
Skin findings:
- Striae caused by rapid weight gain.
  - Violaceous striae may indicate Cushing syndrome.
- Acanthosis nigricans and skin tags may indicate insulin resistance.
- Severe acne and hirsutism in pubertal girls may suggest polycystic ovary disease.
Signs associated with syndromic obesity:
- Neurodevelopmental delay
- Dysmorphic facial features
- Polydactyly
- Short stature
- Hypotonia
Signs associated with underlying causes or complications of obesity:
- Abnormal gait, hip, knee, or foot tenderness, or limited range of motion in the hip.
- Hepatomegaly or right upper quadrant tenderness.
- Goiter.
- Premature appearance of secondary sexual characteristics in females.
- Pseudogynecomastia (adipose tissue mimicking breast development)

Complications and Associated Comorbidities

Metabolic:
- Insulin resistance
- Type 2 diabetes
- Dyslipidemia
Cardiovascular:
- Hypertension
- Coronary artery disease
Hepatic:
- Non-alcoholic fatty liver disease (NAFLD)
- Non-alcoholic steatohepatitis (NASH)
Respiratory:
- Obstructive sleep apnea
- Asthma
Musculoskeletal:
- Osteoarthritis
- Pseudotumor cerebri
Dermatological:
- Acanthosis nigricans
- Skin tags
- Striae
Psychosocial:
- Low self-esteem
- Social stigmatization
- Depression
- Anxiety

Diagnostic Workup

Fasting blood glucose or HbA1c test: To determine glycemic dysregulation.
Fasting or non-fasting lipid profile: To assess dyslipidemia.
Liver function tests (ALT and AST): To screen for NAFLD.
25-hydroxy (25OH) vitamin D test: Many children have vitamin D deficiency.
Blood pressure: If the child is older than three years of age.
Other studies based on history:
- Sleep study for snoring, daytime sleepiness, disrupted sleep cycle, or hyperactivity.
- Liver imaging if liver function tests are high.
- Uric acid level for children with diabetes, prediabetes, high-intake of high fructose corn syrup and table sugar.

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Description

This quiz explores the definition, assessment, and categories of obesity. It includes information on BMI percentiles and growth charts used for determining weight status in children and adolescents. Delve into the various classifications of obesity and the implications of excess body fat.