Reference Ranges Should Be Updated

As a laboratory physician who has worked in this area for years, I would like to point out the following: in Table 1 of the article (1), the normal value for ferritin in women is given as 15–150 µg/L. In my opinion, the lower ferritin values in women are simply a hallmark of the iron deficiency endemic in women who menstruate. In recent years, a lower cut-off value of 30 µg/L is mostly used for both sexes. A current publication even mentions a limit value of 50 µg/L (2). Moreover, a reference value of ≥ 26 pg is given for reticulocyte hemoglobin in Table 1 (1). I am familiar with a reference value of ≥ 28 pg. As reticulocyte hemoglobin is the precursor to mean corpuscular hemoglobin (MCH), it is not clear why it should be lower (3).

Unfortunately, the article (1) contains company-specific terms, such as CHr for reticulocyte hemoglobin, and HYPO for the proportion of hypochromic erythrocytes. These are used by the company Siemens Healthineers on their hematology devices. At Sysmex, they are called Ret-He and Hypo-He. This is an issue in laboratory medicine and hematology, which have not managed to introduce standardized, industry-independent designations for such “new” parameters (available since the mid-1990s). The abbreviation MRH (mean reticulocyte hemoglobin) is suitable for CHr/Ret-He, in analogy to MCH (4).

The disadvantage of using MCV as a classification criterion (Figure 2 [1]) is that it takes weeks before a change in the erythrocyte pool becomes visible. Using reticulocyte hemoglobin, on the other hand, allows the iron availability for erythropoiesis to be assessed in real-time. I recommend determining the reticulocyte count with MRH and ferritin as a basic diagnostic parameters of anemia. Reduced levels of ferritin and MRH are indicative of an uncomplicated iron deficiency; levels of ferritin >100 µg/L and MRH < 28 pg are indicative of an inflammatory reaction.