Malnutrition in a child (obesity, rickets)

Question 1

Define rickets.

Answer 1

Rickets refers to changes caused by deficient mineralisation at the growth plate of long bones, commonly due to nutritional deficiency of vitamin D.

Question 2

What is the difference between osteomalacia and rickets? (When does each occur? Who is affected?)

Answer 2

Rickets and osteomalacia usually occur together while the growth plates are open in children but rickets only occurs in growing children before fusion of the epiphyses

Osteomalacia can occur after the growth plates have fused.

Question 3

Other than nutritional vitamin D deficiency, what are the causes of rickets?

Answer 3

1. Calcium-deficient rickets with secondarily elevated PTH:

Lack of vitamin D due to:

• Decreased sun exposure
• Dietary lack
• Malabsorption
• Liver disease
• Anticonvulsant drugs
• Renal osteodystrophy
• defect in 1-alpha-hydroxylase –> no conversion of 25-hydroxyvitamin D into the active form (type I or pseudovitamin D-deficient rickets)

End-organ resistance

• Rare autosomal recessive disorder can cause mutations in the vitamin D receptor –> end-organ resistance to calcitriol (type II vitamin D-dependent rickets).

Dietary calcium deficiency.

2. Phosphate-deficient rickets (PTH not elevated) may be caused by:

• Renal phosphate wasting
• Phosphate deficiency from poor intake or malabsorption.

Question 4

How do anticonvulsant drugs cause rickets?

Answer 4

Phenytoin may cause target organ resistance to calcitriol

Question 5

How can liver disease cause rickets?

Answer 5

Affects conversion of colecalciferol to calcidiol

Question 6

What are the causes of renal phosphate wasting?

Answer 6

Causes can be genetic or oncogenic.

1. Genetic hypophosphataemic rickets e.g. X-linked/autosomal dominant or recessive/hereditary hypophosphataemic rickets, McCune-Albright syndrome, Fanconi syndrome, renal tubular acidosis (type 2/proximal)
2. Oncogenic hypophosphataemia

Question 7

What are the mechanims of vitamin D formation in the body?

Answer 7

Dependant on sunlight and enzymatic conversion in the liver and kidneys:

• 7-dehydrocholesterol –(UV)–> colecalciferol (vitD3)

OR

• dietary colecalciferol(D3)/ergocalciferol (D2) –(vitD 25-hydroxylase)–> calcidiol (25-hydroxyvitamin D)
• clacidiol –(1-alpha-hydroxylase)–> calcitriol (1,25-dihydroxyvitamin D)

Question 8

Where is Vit D 25-hydroxylase found? Where is 1-alpha-hydroxylase found?

Answer 8

1. vitamin D 25 hydroxylase - liver
2. 1-alpha-hydroxylase - kidneys

Question 9

What is the epidemiology of rickets?

Answer 9

Peak incidence at 6-23 months and 12-15 years

US incidence in those <3 years was 24 per 100,000 in 2000s

Genetic causes are very rare (<1 in 20,000 affected)

Question 10

Why is increased skin pigmentation associated with rickets?

Answer 10

Increased skin pigmentation leads to reduced capacity to synthesise colecalciferol

Question 11

What are the risk factors for rickets?

Answer 11

• Inadequate exposure to sunlight
• Age 6-23 months
• Breastfeeding
• Inadequate calcium and phosphate intake
• Family history
• Darker skin complexionn- requires increased sunlight exposure

Question 12

What are the symptoms of rickets?

Answer 12

Bone pain

Muscle weakness

Paraesthesias /tetany /numbness /seizures (hypocalcaemia)

Question 13

What are the signs of rickets on examination?

Answer 13

• Growth retardation
• Delayed achievement of motor milestones
• Bony deformities e.g. bowlegs, rachitic rosary of the chest
• Fractures
• Hypocalcaemia - Chvostek’s, Trousseau’s, carpopedal spasm

Question 14

What investigations would you do for rickets?

Answer 14

Bloods and urine:

• Calcidiol levels (N:>25nm/L)
• Calcium (N:2.3-2.7mmol/L)
• Serum PTH (N:1-6picomoles/L; elevated)
• ALP(high = high bone turnover) and LFTs
• Creatinine and urea (for kidney disease)
• Urinary calcium and phopshate (low and high)

Imaging: X ray of long bones

Question 15

What would an X ray of long bones show in rickets?

Answer 15

• Widening of the epiphyseal plate e.g. at wrist
• Loss of definition of zone of provisional calcification at epiphyseal/metaphyseal interface
• Cupping /splaying/fraying of metaphysis
• Looser’s zone (pseudofractures)

Question 16

What is shown?

Answer 16

rosary beading of the chest in rickets

Question 17

What is shown?

Answer 17

• Widening of the epiphyseal plate
• Loss of definition of zone of provisional calcification at epiphyseal/metaphyseal interface
• Cupping /splaying/fraying of metaphysis

Question 18

How many units of vitamin D are in 5 micrograms or colecalciferol/ergocalciferol?

Answer 18

200 units

Question 19

What is the management of rickets in children?

Answer 19

Loading dose regimens used for 8-12 weeks

Question 20

What is the loading dose regimen for infants 1-5 months old?

Answer 20

3000 IU daily for 8-12 weeks

Question 21

What is the loading dose regimen for children 8 years old?

Answer 21

6 months to 11 years: 6000 IU daily for 8-12 weeks

Question 22

What is the loading dose regimen for teenagers?

Answer 22

12-18 year olds: 10,000 IU daily for 8-12 weeks (a single or divided dose orally of 300,000 IU can be considered if there is concern about compliance with treatment)

Question 23

How do you manage vitamin D deficiency in a patient who is non compliant with daily medication?

Answer 23

Equivalent weekly or fornightly doses can be given instead and are as effective.

Question 24

What is the vitamin D preparation of choice for rickets?

Answer 24

Colecalciferol (vitamin D3)

Question 25

What if someone cannot take vitamin D3 for religious, cultural or dieary reasons?

Answer 25

Vitamin D2 can be given instead (ergocalciferol)

*NB: VitD3 is an animal source, or gelatine may be used in some preparations

Question 26

What is Stoss therapy?

Answer 26

A high dose of oral vitamin D2 given as a single dose

Question 27

Is wrist enlargement reversible?

Answer 27

May be reversible with calcium supplementation within 6 months but knee deformity may not resolve spontaneously

Question 28

What is hungry bone syndrome?

Answer 28

Whereby vitamin D therapy in hypocalcaemic rickets leads to worsening hypocalcaemia. Consider supprementing breastfed infants with calcium during first few days of therapy to prevent seizures.

Question 29

How is obesity defined in children?

Answer 29

In children, BMI (weight in kg/height in m2) is expressed as BMI centile in relation to age and sex matched population

Question 30

What is the definition of overweight and obesity in children?

Answer 30

Overweight = BMI over 91st centile

Obese = BMI over 98th centile

Question 31

What are the complications of obesity?

Answer 31

• Orthopaedic – slipped upper femoral epiphysis, tibia vara (bow legs), abnormal foot structure and function
• Idiopathic intracranial hypertension (headaches, blurred optic disc margins)
• Hypoventilation syndrome (daytime somnolence, sleep apnoea, snoring, hypercapnia, heart failure)
• Non-alcoholic fatty liver disease
• Gall bladder disease/gallstones
• Polycystic ovarian syndrome
• Type 2 diabetes mellitus
• Hypertension
• Abnormal blood lipids
• Other medical sequelae, e.g. asthma, changes in left ventricular mass, increased risk of certain malignancies (endometrial, breast, and colon cancer)
• Psychological sequelae – low self-esteem, teasing, depression

Question 32

What screening programme is available for obesity?

Answer 32

In the UK, the National Child Measurement Programme measures height and weight to assess overweight and obesity in children in:

1. reception class at school (aged 4–5 years)
2. in year 6 (aged 10–11 years)

Question 33

What is the aetiology of obesity?

Answer 33

• No conclusive evidence that obese children eat more
• But children’s energy expenditure has decreased - less walking, more sedentary activities
• Low socioeconomic homes are more likely to be obese

Question 34

At what age group has obesity most increased between 1994 to 2014?

Answer 34

All age groups but mostly 11-15 year olds

More in boys than girls

Question 35

In terms of height for age, how do obese children fare?

Answer 35

Should be above the 50th centile for height (tall and obese)

If a child is obese and short, an endogenous cause, i.e. hypothyroidism and Cushing syndrome, should be considered.

Question 36

What is the management of obesity in childhood?

Answer 36

SUSTAINED lifestyle changes:

• Healthy eating
• Pyshical activity
• Limiting TV and small screen activities

Drug treatment and surgery - only applicable in those aged >12 years with extreme obesity (BMI >40kg/m2) or BMI >35kg/m2 and complucations of obesity.

• Orlistat - lipase inhibitor reducing fat absorption
• Bariatric surgery - not appropriate unless achieved maturity or very severe complications of obesity are found

These should be used in conjunction with diet and exercise behavioural weight management programmes and be restricted to specialist centres with multidisciplinary expertise in managing severe obesity

More integration of services for obesity is needed overall.

Question 37

What is the prognosis with obesity managements?

Answer 37

Lifestyle changes are difficult to achieve and even harder to maintain.

A cultural change from an obesogenic environment is needed, e.g. reduction or removal of unhealthy food and drinks and a more integrated approach involving health, local government and other key partners.