The consequences of vitamin D (califerol) deficiency are low calcium and phosphate producing secondary hyperparathyroidism, a further reduction in phosphate levels and increased plasma levels of bone-derived alkaline phosphatase.

Clinically, this produces poor bone mineralisation - rickets in children, osteomalacia in adults:

• children with rickets classically present with bony abnormalities such as leg-bowing and knock-knees
  • may also be bony deformities of the chest, pelvis and skull, fractures in severe cases, delayed dentition, poor growth, and, rarely, bone pain
  • symptoms of hypocalcaemia, such as neuromuscular irritability (e.g. convulsions, tetany), cardiomyopathy or cardiac arrest may be the presenting feature - this is especially the case in very young infants
  • commonest cause of rickets is simple nutrient deficiency of vitamin D (from sunlight, diet or both)
• osteomalacia occurs if vitamin D deficiency occurs after closure of the epiphyses

Depending on the cause, there may be a rapid response to administration of small doses of calciferol.

Vitamind D deficiency (insufficiency) in adults:

• in adults, lesser deficiency (insufficiency) is associated with various non-specific symptoms
  
  
• vitamin D deficiency and insufficiency are becoming more common in developed countries
  • in the UK, the prevalence of vitamin D deficiency in all adults is around 14.5%, and may be more than 30% in those over 65 years old, and as high as 94% in otherwise healthy south Asian adults
    
    
• in adults, extensive covering with clothing, failure to spend time outdoors or the use of anti-UVB sunscreens results in decreased skin synthesis of vitamin D and increases the likelihood of primary vitamin D deficiency, as does an inadequate diet
  • in adults over 65 years of age, an inadequate diet, reduced gut absorption and reduced mobility increase that risk, especially in those in residential care (2,3)
    
    
• a consensus statement representing the unified views of a number of organisations (the British Association of Dermatologists, Cancer Research UK, Diabetes UK, the Multiple Sclerosis Society, the National Heart Forum, the National Osteoporosis Society and the Primary Care Dermatology Society), states that the evidence suggesting that vitamin D might protect against cancer, heart disease, diabetes, multiple sclerosis and other chronic diseases is still inconclusive. Furthermore, there is no standard definition of what constitutes an optimal level of vitamin D (4)
  
  
• treatment of low vitamin D levels is not clearly defined or supported by a robust evidence base or national guidance - it relies heavily upon expert consensus (4)
  
  

• opinions on optimal vitamin D serum concentrations in adults vary but the following have been taken from the literature, consensus guidelines from other UK areas (4)

  • Optimal: 75nmol/L or more
    
    
  • Adequate: 50-74nmol/L
    
    
  • Insufficiency: 30-50nmol/L
    
    
  • Deficiency: Less than 30nmol/L
  
  

Reference:

1. Drug and Therapeutics Bulletin 2006; 44 (2):12-16.
2. Drug and Therapeutics Bulletin 2006;44 (4);25-9
3. Pearce S, Cheetham D et al, Diagnosis and management of vitamin D deficiency. BMJ 2010; 340: b5664
4. Consensus Vitamin D position statement, (represents the unified views of the British Association of Dermatologists, Cancer Research UK, Diabetes UK, the Multiple Sclerosis Society, the National Heart Forum, the National Osteoporosis Society and the Primary Care Dermatology Society) - December 2010