Calcium requirement in children

What it is

What the child needs of calcium is tied to vitamin D, and the two are given together. A daily intake of 400 IU of vitamin D is recommended in infants, children and adolescents. When calcium, vitamin D or phosphate is short, the result is nutritional rickets.

Causes and risk

Nutritional rickets comes from deficiency of vitamin D, calcium or phosphate, either from poor intake or from lack of sun exposure. Feeding is where the lack usually starts:

• Breastfeeding does not provide adequate levels of vitamin D.
• Exclusive formula feeding probably provides adequate levels, but an infant who takes less than 1 liter of formula per day needs supplementation.

Two other forms are described next to the nutritional one. In vitamin D dependent rickets type 1 the 1a-hydroxylase enzyme is deficient and the pattern is autosomal recessive, so conversion of 25(OH)D to the active form is impaired. In type 2 there is end-organ resistance to the active form through a mutation in the vitamin D receptor.