Obesity

Question 1

Obesity - background

Answer 1

1. Definition based on WHO growth charts.
   - Overweight = greater than 1SD above mean (equivalent to 30kg/m2 at 19y)
   - Obesity = greater than 2SD above mean (equivalent to 30kg/m2 at 19y)
2. Most common nutritional disorder affecting children and adolescents in the developed world. Australian prevalence = 8%
3. Strongly predicts obesity in adulthood

Question 2

Obesity - risk factors

Answer 2

1. Parental/family history of obesity
2. Afro-Caribbean/Indian-Asian ethnic origins
3. Catch-up growth (weight) in early childhood (0-2y) = infants born SGA who demonstrate significant weight catch up (>2SD) in first two years of life

Question 3

Obesity - causes

Answer 3

1. Idiopathic (‘simple’) obesity is the most common cause (95% of cases)
   Multifactorial in origin (daily energy intake exceeds energy expenditure):
2. Genetic predisposition (energy conservation)
3. Increasingly sedentary lifestyle
4. Increasing consumption and availability of high energy foods
5. Obesity may also be associated with other underlying pathological conditions

Question 4

Obesity - pathological causes

Answer 4

Endocrine (rare)

1. Hypothyroidism
2. Cushing’s syndrome
3. Growth hormone deficiency
4. Pseudohypoparathyroidism
5. PCOS

Genetic syndromes

1. Prader-Willi syndrome
2. Bardet-Biedl syndrome
3. Monogenic causes (e.g. leptin deficiency)

Question 5

Obesity - hx

Answer 5

1. Birth weight (note if SGA)
2. Feeding habits and behaviour (esp. infancy/early childhood). Hyperphagia may suggest genetic cause. Physical activity
3. Weight gain/growth pattern (check previous health records)
4. Neurodevelopment + school performance
5. FHx = obesity, T2DM, CVD

Question 6

Obesity - ix (3)

Answer 6

Laboratory ix directed at excluding secondary causes of obesity

1. Bloods (5) = FBE, TFTs, serum cortisol, LFTs, fasting lipid profile
2. Genetic studies (e.g. Prader-Willi syndrome)
3. OGTT. Consider when one or more of the following risk factors are present (5):
   a. Severe obesity (BMI>98th centile)
   b. Acanthosis nigricans
   c. Positive FHx T2DM
   d. Ethnic origin - Asian, Afro-Caribbean, African-American
   e. PCOS

Question 7

Obesity - mx

Answer 7

1. Mostly managed in primary care; specialist paediatric ax indicated if complications, or an endogenous cause suspected
2. Nutrition and lifestyle education/counselling (no fizzy drinks or sugar-containing juices; decrease food portion size by 10-20%, increase protein and non-carbohydrate-containing vegetables). Decreasing calorie intake and increasing exercise (60 mins of moderate to vigorous daily physical activity)
3. Behaviour modification and family therapy strategies
4. Drug tx if children >12y with extreme obesity (BMI>40, or BMI>35 + complications). Only after dietary, exercise and behavioural approaches have been started. Orlistat (lipase inhibitor), metformin (increases insulin sensitivity and decreases gastrointestinal glucose absorption)
5. Obesity/bariatric surgery (rarely) = not appropriate unless almost achieved maturity, or have very severe/extreme obesity with complications

Question 8

Obesity - complications (5+5)

Answer 8

1. Orthopaedic = SUFE, tibia vara (bow legs), abnormal foot structure/function
2. Idiopathic intracranial HTN (headaches, blurred optic disc margins)
3. Hypoventilation syndrome (daytime somnolence, sleep apnoea, snoring)
4. Gallbladder disease
5. PCOS
   ___
6. T2DM
7. HTN
8. Abnormal blood lipids
9. Other medical sequelae = asthma, increased risk of endometrial/breast/colonic carcinoma
10. Psychological sequelae = low self-esteem, teasing, depression