Table 3.
Prevalence of Iron Deficiency in Relation to the Development of Severe Anemia, According to Several Peripheral Blood Markers.*
| Marker | Prevalence | Multivariate Analysis | |
| Case Patients | Control Patients | Odds Ratio (95% CI)† | |
| no./total no. (%) | |||
| TfR-F index‡ | 97/208 (46.6) | 288/415 (69.4) | 0.37 (0.22–0.60) |
| Alternative definitions | |||
| CRP-containing index§ | 35/208 (16.8) | 212/415 (51.1) | 0.29 (0.16–0.53) |
| Microcytosis¶ | 48/316 (15.2) | 182/636 (28.6) | 0.47 (0.29–0.76) |
| Hypochromasia‖ | 137/314 (43.6) | 294/637 (46.2) | 0.61 (0.41–0.91) |
| Microcytosis and hypochromasia | 26/316 (8.2) | 108/638 (16.9) | 0.40 (0.22–0.72) |
Other markers that were assessed but not presented because they predicted iron deficiency less well (with sensitivity, specificity, or both under 40%) were ferritin, transferrin receptor, serum iron, serum transferrin, total iron-binding capacity, and transferrin saturation. CI denotes confidence interval, CRP C-reactive protein, and TfR-F index the ratio of soluble transferrin receptor to log ferritin.
The odds ratios were obtained by replacing the original variable for iron deficiency in the multivariate analysis with the alternative definition.
The original definition of iron deficiency was a TfR-F index greater than 5.6.
Iron deficiency is defined as a CRP-containing index (0.34 + 0.0043 × ferritin − [2.7 × TfR] ÷ ferritin + 0.0696 × CRP + 0.05 × TfR) of less than 0.26
Microcytosis is defined as a mean corpuscular volume of less than 67 fl in children under 2 years of age and less than 73 fl in children 2 to 5 years of age.27
Hypochromasia is defined as a mean corpuscular hemoglobin concentration of less than 32 g per liter.27