What causes rickets?
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.
In rickets, another mechanism in the body works to increase the blood calcium level. The parathyroid gland (four numbers of hormone producing glands, usually located in the neck) may increase its functioning rate to compensate for decreased levels of calcium in the bloodstream. To increase the level of calcium in the blood the hormone destroys the calcium present in the bones of the body and this results in further loss of calcium and phosphorous from the bones. In severe cases, cysts may develop in the bones. Vitamin D deficiency could be caused due to numerous reasons.
Vitamin D may be absorbed from food by the intestines or may be produced by the skin when the skin is exposed to sunlight. In its active form, vitamin D acts as a hormone to regulate calcium absorption from the intestine and to regulate levels of calcium and phosphate in the bones. Sunlight is important to skin production of vitamin D, and environmental conditions where sunlight exposure is limited may reduce this source of vitamin D. Lack of vitamin D production by the skin may occur if a person is confined indoors, or works indoors during the daylight hours, or lives in climates with little exposure to sunlight.
Because vitamin D is a fat-soluble vitamin, conditions that reduce digestion or absorption of fats will decrease the ability of vitamin D to be absorbed from the intestines. When the body is deficient in vitamin D, it is unable to properly regulate calcium and phosphate levels. If the blood levels of these minerals become too low, other body hormones may stimulate release of calcium and phosphate from the bones to the bloodstream to elevate the blood levels.
Rickets is a bone disease that affects children when these deficiencies occur. It causes progressive softening and weakening of the bones' structure. There is a loss of calcium and phosphate from the bones, which eventually causes destruction of the supportive matrix. Nutritional causes of rickets occur because of a lack of vitamin D in the diet or in association with malabsorption disorders characterized by poor fat absorption.
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). A dietary lack of calcium and phosphorous may also play a part in the nutritional causes of rickets. Rickets caused by a dietary lack of these minerals is rare in developed countries because calcium and phosphorous are present in milk and green vegetables.
Hereditary rickets is an inherited form of the disease caused when the kidneys are unable to retain phosphate. Rickets may also be caused by kidney disorders involving renal tubular acidosis. Occasionally, it can also affect children who have disorders of the liver, do not adequately absorb fats and vitamin D, or cannot convert vitamin D to its active form. Renal osteodystrophy occurs in people with chronic renal failure. The manifestation is virtually identical to that of rickets in children and that of osteomalacia or osteoporosis in adults.