RICKETS

RICKETS

Part of “CHAPTER 70 – DISORDERS OF CALCIUM AND BONE METABOLISM IN INFANCY AND CHILDHOOD“

Rickets may be defined as a disorder in which there is a lag in the rate of mineralization of the matrix of bone and growth cartilage. Growth plate cartilage typically hypertrophies in an unorganized fashion, producing the characteristic widened ends of the long bones seen in this disorder. The formation of hydroxyapatite depends on adequate concentrations of extra-cellular calcium and phosphate; therefore, a deficiency of either or both of these minerals may cause rickets.

There are more than 30 causes of rickets: One classification scheme that categorizes the various forms of rickets is shown in Table 70-2 (see Chap. 63).

VITAMIN D–DEPRIVATION AND CALCIUM DEFICIENCY

There has been a resurgence of vitamin D–deprivation rickets associated with breast-feeding and special dietary practices, including macrobiotic and other vegetarian diets. Human breast milk may provide as little as 10 to 20 IU of vitamin D per day, and macrobiotic diets may provide comparable amounts of vitamin D. Marginal vitamin D stores are often present in the breast-feeding mother of a rachitic infant. Thus, infants who receive only human milk and children who receive macrobiotic diets are at high risk for developing rickets in the early months and years of life.

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