The main cause of rickets is the deficiency of vitamin D caused in the body during childhood. Vitamin D is a fat-soluble vitamin that may be absorbed from the intestines or may be produced by the skin when the skin is exposed to sunlight (ultraviolet light of sunlight helps the body to form vitamin D). The absorbed vitamin D is converted into its active form to act as a hormone to regulate calcium absorption from the intestine and to regulate levels of calcium and phosphate in the bones. If there is a deficiency of Vitamin D, the body is unable to properly regulate calcium and phosphate levels. When the blood levels of these minerals become too low, it results in destruction of the support matrix of the bones.
Environmental conditions where sunlight exposure is limited like indoor confinement or working indoors during daylight hours may reduce source of vitamin D.
A lack of vitamin D in the diet.
Problem of malabsorption called steatorrhea, in which the body is unable to absorb fats, and they are passed directly out the body in the stool. The result of this problem is that Vitamin D, which is usually absorbed with fat, and calcium are poorly absorbed. This poor absorption can be a result of digestive disorders. Steatorrhea could also lead to other deficiencies.
Due to tubular acidosis in which there is an increased amount of acid in the body fluids as a result of congenital or acquired kidney disorders.
A dietary lack of calcium and phosphorous may also play a part in nutritional causes of rickets.
A dietary lack of vitamin D may occasionally occur in people on a vegetarian diet who do not drink milk products or in people who are lactose intolerant (have trouble digesting milk products).