The validity of commonly used haematological indices in the detection of iron deficiency in pregnancy

Abstract

SummaryRationale: The haemoglobin concentration (Fib) has limitations in the diagnosis of iron deficiency in pregnancy.Objective: The objective of this study was to assess the validity of the accepted cut off points of the other commonly measured haematological indices in either detecting or excluding iron deficiency as determined by the serum ferritin (SF) assay. Design:A cross sectional study was carried out on two groups of women in the second and third trimesters of pregnancy.Setting: University Antenatal Clinic, Faculty of Medicine and Kyoto Medical Centre Galle. Method:The Hb, haematocrit (Hct), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemo globin concentration (MCHC) and red blood cell count (RBCC) were estimated by an automated haematology analyser and compared with the SF levels measured by immunoradiometric assay, in 156 women in the second trimester (T 2 ) and 47 women in the third trimester (T } ) of pregnancy. The sensitivity, specificity, positive predictive value, negative predictive value, accuracy and the Kappa statistic were calculated for the accepted cut off points for diagnosis of anaemia, for each haematological index, using a SF<12/ig/L as the diagnostic criterion for iron deficiency. Results:The Hct, MCV and MCHC had a high specificity (96-100%) but a very low sensitivity (10-38%). Only the MCH had a high sensitivity (92% in T 2 ,86% in T 3 ) but it had a low specificity (21-24%). The MCHC had the best accuracy (71% in T3) but its accuracy in T 2 was only 64%. Only the MCHC in T 3 showed some agreement with SF (Kappa 0.41, p=0.00). Conclusion:A single haematological index per se has a poor ability of detecting or excluding iron deficiency in pregnancy. Although the best index is the MCHC, its accuracy is only 64% in the second trimester. Therefore several indices should be evaluated before deciding on a diagnosis of iron deficiency and subsequent supplementation or therapy during pregnancy.

Iron deficiency anaemia in pregnancy and its prevention; paradigm changes over three decades

“…Ten studies on the detection and prevention of ID and IDA in pregnancy, carried out from 1990 to 2017 at the AOGU of the THMG are described. The objectives of these were to: describe the rates of ID and IDA in women presenting for antenatal care in 1990 and compare with the same in 2015 ( 24.25); describe the effectiveness of the antenatal oral iron supplementation programme in 1992 (26); measure the agreement between haematological indices obtained by different laboratories in 2000 (27) and compare with the same in 2015 (28); assess the validity of commonly used haematological indices (29); describe the effectiveness of intermittent antenatal oral iron supplementation between 1994 to 1996 (30)(31)(32) and compare it with the same in 2015/2016 (33).…”