Use of advanced red blood cell and reticulocyte indices improves the accuracy in diagnosing iron deficiency in pregnant women at term.

Objectives: Detection of iron deficiency during pregnancy with hemoglobin (Hb) and serum measurements is insignificant as the measurements may be affected by e.g. hemodilution or accelerated erythropoiesis. This study tests whether cell indices will give a more reliable measure of iron deficiency in pregnant women at term.

Methods: The population was 202 pregnant women. Using the ADVIA 120 hematology system, Hb, mean cell volume (MCV), percentage of hypochromic red blood cells (%HYPOm) and reticulocytes (%HYPOr), and cellular hemoglobin in reticulocytes (CHr) were tested. Additionally, transferrin saturation (TfSat), ferritin, and transferrin receptor (TfR) were analyzed. Receiver operating characteristic (ROC) curves and area under the ROC curves (AUC) were used as statistical methods.

Results: When TfSat (< or = 11%) was used as the reference test for iron deficiency, %HYPOm and CHr had a sensitivity of 58.1% and 80.7%, while the specificities were 82.6% and 71.3%, respectively. Additionally, the AUC values were %HYPOr 0.80, CHr 0.79, ferritin 0.77, %HYPOm 0.75, TfR 0.67, MCV 0.63 and Hb 0.64. The results provided by the cell indices alone (%HYPOm or CHr) were in good agreement with the results based on the usage of a combination of three commonly used tests (Hb, MCV, ferritin).

Conclusions: This study suggests that the most practical way to diagnose iron deficiency in pregnant women at term is to use cell indices such as CHr and %HYPOm provided by the automated hematological analyzer. Further studies are needed to determine the usefulness of the cell indices in diagnosing iron deficiency longitudinally during the course of pregnancy.