Rickets

Question 1

What is rickets?

Answer 1

A condition that results in weak or soft bones in children

Question 2

What is the most common cause of rickets?

Answer 2

Vitamin D deficiency

Question 3

Where is vitamin D derived from?

Answer 3

Two main sources;

• Synthesis from skin following exposure to UV light
• Diet

Question 4

What are the main functions of vitamin D?

Answer 4

• Regulation of calcium and phosphate metabolism

- Functions in the immune system

Question 5

What is the result of vitamin D being involved in the regulation of calcium and phosphate metabolism?

Answer 5

Makes it essential for bone health

Question 6

What happens if vitamin D is not supplied in adequate levels in childhood?

Answer 6

Rickets will develop

Question 7

What does vitamin D deficiency usually result from?

Answer 7

• Inadequate UVB exposure
• Deficient intake
• Defective metabolism of vitamin D

Question 8

What effect does a vitamin D deficiency have on calcium?

Answer 8

It causes a low serum calcium

Question 9

What is the result of a low serum calcium?

Answer 9

It triggers the secretion of PTH

Question 10

What effect does an increased secretion of PTH have?

Answer 10

• Normalises calcium, but demineralises bone

- Causes loss of renal phosphate, and subsequently low serum phosphate levels

Question 11

What is the result of low serum phosphate levels?

Answer 11

It further reduces the potential for bone calcification

Question 12

What are the categories of causes of rickets?

Answer 12

• Nutritional (primary) rickets
• Intestinal malabsorption
• Problems with 25-hydroxyvitamin D
• Problems with 1,25-dihydroxyvitamin D

Question 13

What are the risk factors for primary rickets?

Answer 13

• Living in northern latitudes
• Dark skin
• Decreased exposure to sunlight
• Maternal vitamin D deficiency
• Diets low in calcium, phosphorus, and vitamin D
• Macrobiotic, strict vegan diets
• Prolonged parenteral nutrition in infancy

Question 14

Give an example of when the diet may be low in calcium, phosphorus, and vitamin D

Answer 14

Exclusive breastfeeding into late infancy

Question 15

What are the causes of intestinal malabsorption?

Answer 15

• Small bowel enteropathy
• Pancreatic insufficiency
• Cholestatic liver disease

Question 16

Give an example of a small bowel enteropathy that can lead to rickets

Answer 16

Coeliac disease

Question 17

Give an example of a cause of pancreatic insufficiency that can lead to rickets

Answer 17

Cystic fibrosis

Question 18

What are the causes of problems with 25-hydroxyvitamin D?

Answer 18

• Defective production
• Increased metabolism
• Defective production

Question 19

Give a cause of defective production of 25-hydroxyvitamin D

Answer 19

Chronic liver disease

Question 20

Give a cause of increased metabolism of 25-hydroxyvitamin D

Answer 20

Enzyme induction by anticonvulsants

Question 21

What are the causes of defective production of 1,25-dihydroxyvitamin D

Answer 21

• CKD
• Fanconi syndrome
• Inherited disorders

Question 22

How can rickets present?

Answer 22

• Craniotabes
• Rachitic rosary
• Widened wrists and ankles
• Harrison’s sulcus
• Poor growth/short stature
• Delayed dentition
• Bowing of weight-bearing bones
• Hypotonia
• Seizures
• Cardiomyopathy/heart failure

Question 23

What are craniotabes?

Answer 23

Softening or thinning of the skull in infants and children, mostly seen in occipital and parietal bones

Question 24

How do craniotabes present?

Answer 24

The bones are soft, and when pressure is applied they will collapse underneath it

Question 25

What is rachitic rosary?

Answer 25

Expansion of the anterior rib ends at the costochondral junctions

Question 26

What is Harrison's sulcus?

Answer 26

A horizontal depression on the lower chest corresponding to the attachment of the softened ribs with the diaphragm

Question 27

What investigations should be done in rickets?

Answer 27

- Bloods | - X-ray of wrist joints

Question 28

What may be found on bloods in rickets?

Answer 28

- Serum calcium low or normal - Phosphorus low - Plasma alkaline phosphatase activity high - 25-hydroxyvitamin D may be low - PTH elevated

Question 29

What does the x-ray of the wrist joint show in rickets?

Answer 29

Cupping and fraying of the metaphyses, and a widened epiphyseal plate

Question 30

What is an important differential diagnosis for rickets?

Answer 30

Bone fracture, can be mistaken for non-accidental injury

Question 31

How is nutritional rickets managed?

Answer 31

- Advice about balanced diet, and foods rich in vitamin D - Correction of pre-disposing risk factors - Daily administration of vitamin D3 (cholecalciferol)

Question 32

Give 2 examples of foods rich in vitamin D

Answer 32

- Oily fish | - Egg yolk

Question 33

How long does healing take after management for rickets?

Answer 33

2-4 weeks

Question 34

What shows healing in rickets?

Answer 34

- Lowering of alkaline phosphatase - Increasing vitamin D levels - Healing on bone x-rays

Question 35

How long does complete reversal of bony deformities take in rickets?

Answer 35

May take years

Question 36

What are the potential complications of rickets?

Answer 36

- Bone fractures - Muscle spasms - Abnormally curved spine - Intellectual disability