Submitted to: American Journal of Clinical Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/10/2004
Publication Date: 11/1/2004
Citation: Graff, M., Thacher, T.D., Fischer, P.R., Stadler, D., Pam, S.D., Pettifor, J.M., Isichei, C.O., Abrams, S.A. 2004. Calcium absorption in Nigerian children with rickets. American Journal of Clinical Nutrition. 80(5):1415-1421. Interpretive Summary: Rickets in toddlers is a large problem in parts of Africa, especially Nigeria. It is not due to vitamin D deficiency but is caused by not having enough calcium in the diet. We wanted to know whether there was a problem with absorbing calcium in children in Nigeria. We measured how much calcium was absorbed in a group of children with rickets and compared that with how much was absorbed by children that did not have rickets. We found that children with rickets were able to absorb calcium normally. This means that it is probably another factor in the diet or an overall lack of calcium that causes the rickets rather than an inability of some children to absorb the calcium that is in their diet.
Technical Abstract: Nutritional rickets is common in Nigerian children and responds to calcium supplementation. Low dietary calcium intakes are also common in Nigerian children with and without rickets. The objective was to assess intestinal calcium absorption in Nigerian children with rickets. Calcium absorption was assessed in 15 children with active rickets (2-8 y of age) and in 15 age- and sex-matched children without rickets by using a dual-tracer stable-isotope method. The children with rickets were supplemented with calcium for 6 mo; calcium absorption was reevaluated 12 mo after the baseline study. Fractional calcium absorption could be determined in 10 children with rickets and in 10 children without rickets. The children with and without rickets had dietary calcium intakes of approximately 200 mg/d. Compared with the control children, the children with rickets had lower serum 25-hydroxyvitamin D and calcium concentrations and greater 1,25-dihydroxyvitamin D and parathyroid hormone concentrations. In fact, there were 15 rachitic and 15 control children in the study. Mean (+/-SD) fractional calcium absorption did not differ between those with (61 +/- 20%) and without (63 +/- 13%) rickets (P = 0.47). Calcium absorption was not associated with serum concentrations of calcium, alkaline phosphatase, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, or parathyroid hormone. Mean fractional calcium absorption was significantly greater after (81 +/- 10%) than before (61 +/- 20%) calcium supplementation for the treatment of rickets (P = 0.035). In Nigerian children with rickets, the capacity to absorb calcium is not impaired; however, fractional calcium absorption increases after the resolution of active disease. Calcium absorption may be inadequate to meet the skeletal demands of children with rickets during the active phase of the disease, despite being similar to that of control children.