Use of MCV, MCH, and RDW in detection of donor-induced iron deficiency

Iron deficiency anemia (IDA) is of concern for regular blood donors. Studies have found red blood cell (RBC) indices particularly useful in the early detection and prevention of IDA (1). The mean corpuscular volume (MCV) and the RBC distribution width (RDW) are especially useful, as these parameters often become abnormal before anemia becomes noticeable in other routine testing (2, 3).

Donor-induced iron deficiency (DIID)

A blood transfusion can in many cases be the only therapy available to treat an acute or chronic health condition. Voluntary blood donors are paramount to blood transfusion services. However, regular donations can cause significant depletion of the body’s iron stores, which might adversely affect the donor’s health as well as the quality of the donated blood (1).

Iron-deficient erythropoiesis results in unevenly small (microcytic) RBCs, and anisocytosis (increased RDW) can be the first laboratory finding that indicates anemia well before hemoglobin levels degrease below reference internals. A prompt detection of subclinical iron deficiency in regular donors is therefore necessary (1).

Singh and colleagues at the Rajarshi Dashrath Autonomous State Medical College, Ayodhya, Uttar Pradesh, India used the Medonic M-series M20M hematology system to evaluate the usefulness of MCV, MCH, and RDW in detection of iron deficiency at an early stage (1). They found significantly lower MCV and MCH values and significantly increased RDW in recurring donors and concluded that proper use of these parameters will be helpful to prevent the development of clinically evident IDA.

Wigina and collegues at the Technical University of Mombasa, School of Applied and Health Sciences, Mombasa, Kenya also used the Medonic M-series M20M hematology system to identify RBC abnormalities in blood donors (4). They found 31.05% of the donor cells exhibiting one or more of assayed abnormalities, with 9.91 % of the donor red cells having MCV values below the reference interval.

Distinguishing IDA from thalassemia

Thalassemia is another cause of microcytic anemia (5). However, while IDA is a nutrient disorder that can be treated with iron supplementation, thalassemia is an inherited disorder that lacks management protocol and for which blood transfusion is a mainstay of treatment (6, 7). The ability to differentiate IDA from thalassemia is important, as blood hemoglobin will not be improved by iron supplementation in thalassemia patients (8).

Together with determination of, for example, serum iron levels, RBC indices can be of good help (5, 8). Many formulas that include the RBC indices have been suggested to discriminate thalassemia from IDA (Table 1).

Table 1. Suggested formulas to distinguish beta-thalassemia trait (β-TT) from iron deficiency anemia (IDA) (adopted from Naizi et al. [5] and Jameel et al. [8])
Index Formula β-TT IDA
Red cell distribution width RDW < 14 > 14
RDWI MCV × RDW / RBC < 220 < 220
Mentzer MCV / RBC < 13 < 13
England & Fraser MCV – (5 × HGB) - RBC < 0 (neg) < 0 (neg)
Srivastava MCH / RBC < 3.8 < 3.8
Shine & Lal MCV × MCV × MCH / 100 < 1530 < 1530
Green & King MCV × MCV × RDW / (HGB × 100) < 72 < 72
Ricerca RDW / RBC < 3.3 < 3.3

Donor assessment

In the donor assessment, only individuals of good health are selected (9). Rapid tests for on-site donor screening are available for many analyses, including hemoglobin, blood type, and common bloodborne infections. Blood cell counts, however, sometimes require that samples are sent to the central laboratory for testing, a procedure often associated with venipuncture and prolonged time from sampling to results.

Boule automated hematology analyzers, such as the Medonic M-series analyzers, have a compact, benchtop design suitable for rapid on-site testing to reduce turnaround time for donor screening. The analyzers also offer the capability of reporting a complete blood count from a finger-stick sample. Blood collection from a fingerstick can be easier on the donor and, at the same time, saves the vein for the actual donation.

Boule automated hematology analyzers report results from a complete blood count, including a WBC differential count, in about one minute from sample aspiration. The knowledge about the presence of RBC abnormalities is an essential tool to mitigate possible effects of such abnormalities, both on donor health as well as on the quality of the final blood product.


  1. Singh et al. Comparative Analysis of Red Cell Parameters of First-time and Repeat Blood Donors: A Descriptive Study. Journal of Clinical and Diagnostic Research 17, EC05–EC07 (2023).
  2. White paper: Clinical utility of red blood cell indices in anemia investigations. Boule Diagnostics, 45000, Edition 1 (2023).
  3. White paper: Hematology testing in blood banking and transfusion applications. Boule Diagnostics, 36366, Edition 4 (2022).
  4. Wigina et al. Occurrence of red blood cell abnormalities in donor blood donated at the regional blood transfusion centre, Mombasa, Kenya. Multidisciplinary Journal of TUM 2, 45–55 (2023).
  5. Niazi et al. Usefulness of red blood cell indices in differentiation of microcytic hypochromic anemias. Gomal J Med Sci8, 125–129 (2010).
  6. Khaliq, S. Thalassemia in Pakistan. Hemoglobin46, 12-14 (2022).
  7. Li et al. The Efficacy and Safety of Vitamin C for Iron Supplementation in Adult Patients With Iron Deficiency Anemia: A Randomized Clinical Trial. JAMA Netw Open3, e2023644 (2020).
  8. Jameel et al. Differentiation of beta thalassemia trait from iron deficiency anemia by hematological indices. Pak J Med Sci33, 665–669 (2017).
  9. Blood Donor Selection: Guidelines on Assessing Donor Suitability for Blood Donation. World Health Organization (2012).

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