A disorder involving softening and weakening of the bones of children, primarily caused by lack of vitamin D and/or lack of calcium or phosphate.

Because vitamin D is fat soluble, conditions that reduce digestion or absorption of fats will decrease the ability of vitamin D to be absorbed from the intestines. 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 with indoor confinement or working indoors during the daylight hours, or it may occur in climates with little exposure to sunlight.

Hereditary rickets is a vitamin D-resistant form of rickets caused when the kidney is unable to retain phosphate. It is an inherited, sex-linked disorder.

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