IRON STATUS, MENARCHE, AND CALCIUM SUPPLEMENTATION IN ADOLESCENT GIRLS

The effects of growth, menstrual status, and calcium supplementation o n iron status were studied over 4 y in 354 girls in pubertal stage 2 w ho were premenarcheal at baseline ((x) over bar +/- SD age: 10.8 +/- 0 .8 y). Girls were randomly assigned to placebo or treatment with 1000 mg Ca/d as calcium citrate malate. Anthropometric characteristics, bon e mass, and nutritional status were measured biannually; ferritin was measured annually; and red blood cell indexes were determined at 4 y. The simultaneous effects of iron intake and menstrual status on serum ferritin, after change in lean body mass (LBM) was controlled for, wer e evaluated in subjects in the upper and lower quartiles of cumulative iron intake. The average maximal accumulation of LBM (386 g/mo; 95% C I: 372, 399) occurred 0.5 y before the onset of menarche. Change in LB M was a significant predictor of serum ferritin (P < 0.0001), with a n egative influence on iron status (t ratio = -4.12). The 2 fitted mathe matical models representing ferritin concentrations of subjects in the upper and lower quartiles of cumulative iron intake were significantl y different (P < 0.018). The regression line of the ferritin concentra tion in menstruating girls with high iron intakes had a less negative slope than the line fit to serum ferritin concentrations in girls with low iron intakes (NS). Serum ferritin concentrations at 0, 1, 2, 3, a nd 4 y were not significantly different between groups. In addition, t here was no significant difference between groups in any of the red bl ood cell indexes. In summary, growth spurt and menstrual status had ad verse effects on iron stores in adolescent girls with low iron intakes (<9 mg/d), whereas long-term supplementation with calcium (total inta ke: approximate to 1500 mg/d) did not affect iron status.