Rickets, due to a deficiency of vitamin D, is far less frequent nowadays than formerly. Vitamin D may be taken into the body as such in foods or cod liver or halibut liver oil, or it may be formed by action of sunlight on the skin. The ultraviolet rays of the sun are important in this respect. In our industrialized cities most children get little direct sunlight. Darkskinned people get less ultraviolet than blond, thin-skinned people.Heavy clothing and window glass also prevent the passage of ultraviolet rays.
Children with rickets have beading of the ribs. They are irritable, restless, fretful, and pale. Most significant, however, are the failures of growth of bones and teeth. The head begins to appear overlarge, with prominent frontal bones; little soft areas may be felt in the bones of the skull. There appear enlargements in the region of the wrist and ankles and the legs get distorted into bowlegs, knockknees, and there are pelvic deformities. The X-ray quickly reveals the extent of the deformities.
Rickets can be prevented by exposure to ultraviolet rays from the sun or an artificial source, but the giving of 400 to 800 units of vitamin D per day is much more certain. Nowadays milk containing vitamin D in adequate amounts is generally available in the United States. When a real deficiency is present vitamin D may be given in one of many different forms including fish liver oils, viosterol, tablets or other preparations.
Excessive vitamin D intake results in a condition called hypervitaminosis D, with many distressing symptoms. Excess calcium may be deposited in various tissues of the body. Stopping the vitamin D promptly gets rid of the annoying symptoms.