Exploring low haemoglobin density as a no-added-cost screening marker to assess iron deficiency

Iron deficiency (ID), with or without anaemia, affects over 1 billion people globally. Early detection is essential, but current diagnostic tools may be costly, logistically complex and not widely accessible. This study evaluates low haemoglobin density percentage (LHD%), derived from mean corpuscular haemoglobin concentration (MCHC) in routine complete blood counts (CBCs), as a no-added-cost, accessible alternative for ID screening.

We retrospectively analysed 3526 adult patient records (January-April 2025) from a single-centre institution, including those with iron panel and CBC performed within 24 h. Patients were categorized as Normal, ID, ID anaemia (IDA) or anaemia without ID (AwoID). LHD% was calculated and assessed across groups using receiver operating characteristic (ROC) curve analyses for cutoff determinations.

Median LHD% increased progressively from the Normal group (2.99%) to the IDA group (6.71%). ROC analysis showed modest but acceptable diagnostic performance: area under the curve (AUC) was 0.677 overall, 0.687 in non-anaemic and 0.684 in anaemic subjects. Specific LHD% cutoffs varied by context: >4.48% for general screening (61% sensitivity, 67% specificity), >7.02% for donor screening (95% specificity) and >3.74% for anaemia workup (75% sensitivity).

LHD% shows potential as a context-specific, no-added-cost screening tool for ID using existing CBC data. While its diagnostic performance is modest, its scalability and accessibility could support broader public health screening efforts. Further prospective validation is recommended.