title: Calcium absorption in Nigerian children with rickets.
abstract: BACKGROUND
  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.
  
  
  OBJECTIVE
  The objective was to assess intestinal calcium absorption in Nigerian children with rickets.
  
  
  METHODS
  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.
  
  
  RESULTS
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Foods and Nutrition, University of Utah, Salt Lake City and Chemical Pathology, University of Jos, Jos, Nigeria.
authors.forename: Mariaelisa
authors.initials: M
authors.lastname: Graff
authors.forename: Tom D
authors.initials: TD
authors.lastname: Thacher
authors.forename: Philip R
authors.initials: PR
authors.lastname: Fischer
authors.forename: Diane
authors.initials: D
authors.lastname: Stadler
authors.forename: Sunday D
authors.initials: SD
authors.lastname: Pam
authors.forename: John M
authors.initials: JM
authors.lastname: Pettifor
authors.forename: Christian O
authors.initials: CO
authors.lastname: Isichei
authors.forename: Steven A
authors.initials: SA
authors.lastname: Abrams
mesh_terms: D002118:Calcium / Q000097:blood / Q000172:deficiency*; D002136:Calcium, Dietary / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000627:therapeutic use; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007408:Intestinal Absorption; D008297:Male; D009549:Nigeria; D012279:Rickets / Q000188:drug therapy / Q000378:metabolism*
chemical_list: D002136:Calcium, Dietary; D002118:Calcium