Answers

View larger version (44K): [in this window] [in a new window] [PowerPoint Slide for Teaching]   Fig 2 Wrist radiograph showing splaying, cupping, and widespread demineralisation

 

View larger version (67K): [in this window] [in a new window] [PowerPoint Slide for Teaching]   Fig 3 Chest radiograph showing prominent costochondral joints (rachitic rosary)

 

1. The growth plate is widened and irregular (an abnormality known as fraying). The metaphyseal ends of the radius and ulna are widened (splaying). The ends of the radius and ulna are concave (cupping). There is widespread demineralisation of bone, seen most obviously at the metaphyseal end of long bones (fig 2).

2. The likeliest explanation is rickets.

3. Children can present with rickets in a variety of ways:

1. Development defects: failure to thrive, short stature, motor developmental delay.
   
2. Bony abnormalities: swollen wrists, rachitic rosary (cupping at the costochondral junction), bowing of the legs, skull bossing, pathological fractures.
   
3. Respiratory problems: recurrent respiratory tract infections, oxygen dependency.
   
4. Biochemical abnormalities: symptomatic hypocalcaemia.
   
5. Incidental findings: classic features seen on radiography (rachitic rosary (fig 3) can be seen at the costochondral junction; fraying, splaying, or cupping may be seen at humeral metaphyses (fig 2), abnormalities noted on blood tests.
   

Discussion

Vitamin D deficiency is reported to be increasing in prevalence in the United Kingdom. In one UK inner city population, the prevalence was 24% overall, with the highest prevalence in Asian women (43%), at least as determined by biochemical testing.¹ A large number of children are subsequently at risk of developing nutritional rickets. Risk factors include being born into a Black or Asian ethnic group living in a temperate climate, prolonged infant breast feeding without vitamin D supplementation, and undiagnosed or subclinical vitamin D deficiency in the mother (table).²

View this table: [in this window] [in a new window]   Causes of rickets

 
Nutritional vitamin D deficiency can present in a variety of ways. Well recognised presentations include delayed walking, short stature, bony abnormalities, and delayed dentition. It can present in more unusual ways, however. A recent study in inner city London showed that 44.6% of children with low vitamin D concentrations on laboratory testing had symptomatic hypocalcaemia. However, 58% of these children had no evidence of rickets radiologically.³ Several case reports of children presenting with hypocalcaemic fits can be attributed to severe nutritional rickets.⁴

A recent review of infants presenting with severe cardiomyopathy and biochemical markers of nutritional rickets showed that rickets is a preventable cause of life threatening infant heart failure. Of the 16 affected infants, six had a cardiac arrest, three died, and two were referred for cardiac transplantation.⁵ Children admitted to hospital with lower respiratory tract infections are also significantly more likely to have rickets than those admitted for other reasons.⁶ A high index of suspicion is required in at risk populations to diagnose rickets in children who present with more unusual symptoms.

The recommended daily intake of vitamin D in infancy is 10 µg or 400 IU. Infant formulas and breast milk do not contain vitamin D in sufficient quantity to satisfy this requirement, and routine supplementation of all infants has been suggested.⁷ Current UK guidance from the National Institute for Health and Clinical Excellence (NICE) states that it is important to maintain adequate vitamin D during pregnancy and breast feeding, and that women can take up to 10 µg vitamin D a day during these periods, particularly if they have specific risk factors for vitamin D deficiency.⁸

Nutritional rickets is treated by exposure to sunlight and vitamin D supplements, which can be given orally or intramuscularly. This may be insufficient in premature neonates, who may need additional calcium and phosphate supplements. Anecdotal experience in our unit suggests that once the nutritional deficit is dealt with, the susceptibility to respiratory tract infections and oxygen dependency in severe rickets reduces.

Cite this as: BMJ 2008;337:a2149