Rickets occurs when the metabolites of vitamin D are deficient. Less commonly, dietary deficiency of calcium or phosphorus may produce rickets. Ergosterol can be taken orally with good effect. The phosphorus level is invariably low for age unless recent partial treatment or recent exposure to sunlight has occurred. Alkaline phosphatase levels are elevated.
Calcidiol levels are low, and parathyroid hormone levels are elevated.
Calcidiol levels, and parathyroid hormone levels are not needed for typical instances. In some circumstances, calcitriol levels are normal or high because of parathyroid activity. The best single x-ray for infants and children younger than 3 years is an anterior view of the knee showing the metaphyseal ends and epiphyses of the femurs and tibiae. This site is best because growth is most rapid there, which accentuates the changes. These metaphyses present widening and cupping because of their exaggerated normal concavity and irregular calcification.