The index of suspicion for iron deficiency in non-anaemic subjects

摘要

Editor – A subnormal level of either the mean corpuscular haemoglobin (MCH) or the mean corpuscular haemoglobin concentration (MCHC) could be the first sign of iron deficiency without anaemia (IDWA). The underlying reason for this phenomenon was identified in a study of 219 female athletes aged 15–20 years. What emerged was that, during the progression from the status of normal iron stores (defined as serum ferritin ≥30 μg/L) to iron deficient status (defined as serum ferritin <30 μg/L) the fall in MCH and MCHC antedated the fall in mean corpuscular volume (MCV), with the consequence that a stage was reached where iron deficient subjects had mean values of MCH and MCHC that were significantly lower (p<0.001) than the levels of those parameters in their iron replete counterparts, despite the fact that mean values for MCV remained the same for both the iron deficient subgroup and the iron replete subgroup. Also among subjects who had progressed to iron deficiency, the mean value for haemoglobin (Hb) was 132.7 g/L vs 139.2 g/L in the iron replete subgroup.1 In a study where iron deficiency was defined as serum ferritin of ≤30 μg/L in men and ≤20 μg/L in females, or transferrin saturation as ≥20%or reticulocyte haemoglobin as ≤28 pg, there were 770 subjects with IDWA. Among them were 463 who had MCH amounting to ≤28 pg vs 209 with MCV of ≤80 fL.2 Accordingly, given the fact that MCH of ≥28 pg is more prevalent than MCV of ≤80 fL in IDWA subjects, a MCH of <28 pg should be a red flag for IDWA, prompting further investigation along the lines proposed by Al-Naseem et al.3