What are Vitamin D Deficiency Disorders?

Vitamin D deficiency mainly causes two health problems namely rickets and osteomalacia. Other disorders due to vitamin D deficiency include bowed legs, skeletal deformation and rachitic rosary. Though vitamin D can be synthesized from sun light, the mounting evidence of skin cancer due to exposure to sunlight is forcing the general population and scientists alike to switch to dietary source of vitamin D.

Vitamin D deficiency is present even in developed countries including USA. The third National Health and Nutrition Examination Survey (NHANES III) has shown that in United States the vitamin D deficiency is prevalent throughout the nation.

The clinical manifestations of vitamin D may be due to deficient production of vitamin D in the skin, diets with low vitamin D content, increase loss of vitamin D, impairment in activation of vitamin D or resistance to effects of 1,25(OH)2D (1,25dihydroxycholecalciferol).

The causes of impaired vitamin D action may be due to:

  • Vitamin D deficiency (diet with poor vitamin D content, mal absorption or less production of vitamin D in skin)
  • increase loss of vitamin D (impaired enterohepatic circulation, increased metabolism due to drugs like rifampin, barbiturates and phenytoin)
  • Target organ resistance (mutation of vitamin D receptors or drugs like phenytoin)
  • impaired 1-alpha hydroxylation (renal failure, hypoparathyroidism, 1-alpha hydroxylase mutation,  X-linked hypophosphatemic rickets, osteomalacia and antifungal drugs like ketokonazole)
  • Impaired 25, hydroxylation (liver disease and drug like isoniazid).


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