Low haemoglobin density for detecting iron deficiency across a large population, including pregnancy

Summary Introduction Low haemoglobin density ( LHD %) from Coulter counters has been suggested as a means to detect iron deficiency. Its performance in a broad population group, including pregnancy, has not been evaluated. Methods A retrospective study of adult and paediatric (under 12 years old) patient samples referred for blood counts and iron studies between October 2013 and March 2015. Receiver operator characteristic ( ROC ) curves were constructed to evaluate the performance of LHD % adults, children, and in the antenatal subgroup. Results Using a strict definition for iron deficiency, compared with a selected normal cohort, LHD % had a ROC area under the curve ( AUC ) of 0.90 (0.89–0.91), but in an unselected cohort, the AUC fell to 0.74 (0.73–0.75) with a sensitivity of 74% and specificity of 60% at a cut‐off value of 5.9%. In the paediatric cohort, the AUC was 0.79(0.73–0.85), giving a sensitivity and specificity of 75% and 68%, respectively. LHD % did not effectively identify iron deficiency in pregnancy with an AUC of 0.60 (0.54–0.65) and was no better than MCV at detecting iron deficiency. Conclusion LHD % detects iron deficiency in adult and paediatric populations, but not in the antenatal setting, and does not appear superior to MCV .