Red Cell and Reticulocyte Parameters for the Detection of Iron Deficiency in Pregnancy

Iron deficiency is a common complication of pregnancy and may lead to anemia as pregnancy progresses. Routine screening tests in pregnancy include hemoglobin levels, but in most centers not a serum ferritin. Advances in red cell and reticulocyte indices on automated blood counters have the potential to detect iron deficiency earlier, but pregnancy is associated with a rapid expansion of the red cell mass and parameters based on the entire erythrocyte population are less sensitive to changes. The objective of this study was to assess whether the Red Cell Size Factor and associated reticulocyte based indices can enable single-platform iron deficiency screening in pregnancy.

Pregnant women had ferritin measured with blood counts and reticulocytes on a Beckman DxH800. The ability of the red cell size factor (RSF) and mean reticulocyte volume (MRV) to detect iron deficiency (ferritin < 10 µg/L) or early iron deficiency (ferritin < 30 µg/L) was assessed by comparing receiver operator characteristic curves and areas under the curve (AUC).

RSF (AUC 0.80) and MRV (AUC 0.80) were both acceptable for detecting iron deficiency, but were not statistically superior to mean cell volume (MCV; AUC 0.77, p = 0.1). However, the optimal cut point for MCV was 86 fL, well above the accepted lower limit of normal. All parameters were poor at detecting early iron deficiency.

Iron deficiency can be detected in pregnancy with red cell and reticulocyte parameters. While a low MCV is suboptimal as a screening test for iron deficiency, an MCV of 86 fL provides similar performance to the other red cell parameters studied.