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[30]                                                                                                                                                                                                                                              AJDHS.COM 

 

 

Available online at ajdhs.com 

Asian Journal of Dental and Health Sciences 
Open Access to Dental and Medical Research 

Copyright  © 2025 The  Author(s): This is an open-access article distributed under the terms of the CC BY-NC 4.0 
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original author and source are credited  

 

 

Mentzer Index as an Indicator of Hematological Health in Pregnant 
Populations: A Review 

Emmanuel Ifeanyi Obeagu *  

Department of Biomedical and Laboratory Science, Africa University, Zimbabwe 

Article Info: 
_____________________________________________ 
Article History: 

Received   08 Nov 2024     
Reviewed  19 Dec 2024 
Accepted   16 Jan 2025 
Published 15 March 2025 

_____________________________________________ 
Cite this article as:  

Obeagu EI, Mentzer Index as an Indicator of 
Hematological Health in Pregnant 
Populations: A Review, Asian Journal of Dental 
and Health Sciences. 2025; 5(1):30-33                                                                     

DOI: http://dx.doi.org/10.22270/ajdhs.v5i1.116          

Abstract 
_________________________________________________________________________________________________________________ 

Hematological health in pregnancy is crucial for ensuring favorable maternal and fetal outcomes, as 
pregnancy often predisposes women to conditions like anemia. The Mentzer Index, a diagnostic ratio 
derived from routine complete blood count (CBC) parameters, has proven valuable in distinguishing 
between iron-deficiency anemia (IDA) and thalassemia traits, two prevalent yet distinct causes of 
anemia in pregnant populations. This tool's simplicity and cost-effectiveness make it especially 
useful in resource-limited settings, offering a practical approach to early diagnosis and tailored 
management strategies. This review highlights the role of the Mentzer Index in assessing maternal 
hematological health, with a focus on its application in differentiating anemia subtypes. By 
comparing mean corpuscular volume (MCV) and red blood cell count (RBC), the index provides an 
accessible preliminary screening mechanism. While an index >13 often indicates IDA, values <13 
suggest thalassemia traits, enabling clinicians to prioritize further diagnostic evaluations, such as 
serum ferritin levels or hemoglobin electrophoresis. This timely differentiation is essential for 
avoiding inappropriate treatments, such as unwarranted iron supplementation in thalassemia 
carriers, which may lead to complications like iron overload. 

Keywords: Mentzer Index, Hematological Health, Pregnancy, Iron-Deficiency Anemia, Thalassemia 
Trait 

*Address for Correspondence:   

Emmanuel Ifeanyi Obeagu, Department of Biomedical and Laboratory Science, Africa University, Zimbabwe 

 

Introduction 

Anemia is a global public health concern, affecting 
approximately 40% of pregnant women, with higher 
prevalence in low- and middle-income countries. The 
physiological changes in pregnancy often exacerbate 
pre-existing anemia or reveal underlying hematological 
disorders. Iron-deficiency anemia (IDA) and 
hemoglobinopathies such as thalassemia traits are the 
two leading causes, presenting a diagnostic challenge 
due to overlapping clinical and hematological features.1-

2 Maternal anemia, if left untreated, can lead to 
complications including preterm labor, low birth 
weight, and impaired cognitive and physical 
development in infants. Severe anemia is also associated 
with maternal mortality, especially in resource-
constrained settings. Differentiating the type of anemia 
is critical, as the management of IDA (requiring iron 
supplementation) differs markedly from that of 
thalassemia traits, where iron overload could 
exacerbate complications.3-4 The conventional 
diagnostic approaches for anemia include serum 
ferritin, hemoglobin electrophoresis, and genetic 
testing. While effective, these methods may not always 
be accessible or affordable, particularly in under-
resourced healthcare systems. A simpler, cost-effective 

diagnostic tool is needed for initial screening to guide 
further investigations and management.5-6 First 
introduced in the 1970s, the Mentzer Index has gained 
recognition as a practical indicator in differentiating IDA 
from thalassemia traits. It is calculated as the ratio of 
Mean Corpuscular Volume (MCV) to Red Blood Cell 
(RBC) count, parameters readily available in routine 
CBC tests. The simplicity and affordability of this 
calculation make it particularly appealing for use in 
pregnancy, where timely diagnosis is crucial.7-8 In 
pregnant populations, the Mentzer Index serves as an 
effective screening tool for anemia, enabling healthcare 
providers to identify the probable cause early in 
prenatal care. This facilitates prompt and appropriate 
management, which is essential for minimizing risks to 
both mother and baby. Despite its utility, the Mentzer 
Index has limitations, such as reduced accuracy in mixed 
anemia cases and the need for population-specific 
threshold adjustments. 8 This review aims to evaluate 
the role of the Mentzer Index as an indicator of 
hematological health in pregnant populations.  

Hematological Health in Pregnancy 

Pregnancy induces significant alterations in the 
hematological system to support the increased demands 
of the developing fetus and maternal tissues. Plasma 

                     Open Access                                                                                                                                                                                                                Review Article                                                                           

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Emmanuel Ifeanyi Obeagu                                                                                                      Asian Journal of Dental and Health Sciences. 2025; 5(1):30-33 

[31]                                                                                                                                                                                                                                              AJDHS.COM 

volume expands by approximately 50%, leading to a 
relative hemodilution known as physiological anemia of 
pregnancy. Concurrently, red blood cell (RBC) mass 
increases, albeit at a slower rate than plasma expansion, 
contributing to decreased hemoglobin concentration. 
These changes are considered normal adaptations but 
can complicate the diagnosis of pathological conditions 
such as anemia.9-10 Anemia is the most common 
hematological disorder in pregnancy, affecting about 
40% of pregnant women globally, with a higher burden 
in low- and middle-income countries. Iron-deficiency 
anemia (IDA) accounts for the majority of cases due to 
increased iron requirements during pregnancy, 
inadequate dietary intake, and frequent gastrointestinal 
losses. Other causes include vitamin B12 and folate 
deficiencies, chronic diseases, and genetic 
hemoglobinopathies such as thalassemia.11-12 Anemia 
during pregnancy poses significant risks to both the 
mother and the fetus. For the mother, severe anemia 
increases the likelihood of preterm labor, postpartum 
hemorrhage, and infection. For the fetus, it can lead to 
intrauterine growth restriction (IUGR), low birth 
weight, and developmental delays. These adverse 
outcomes underscore the importance of timely 
identification and management of anemia in pregnant 
populations.13-14 

Routine screening for anemia in pregnancy involves 
hemoglobin estimation, red blood cell indices, and 
peripheral blood smear analysis. Advanced diagnostics 
like serum ferritin, transferrin saturation, and 
hemoglobin electrophoresis are used to pinpoint the 
underlying cause. However, these methods may be 
inaccessible or unaffordable in resource-limited 
settings, necessitating simpler tools such as the Mentzer 
Index for preliminary assessment.15 The management of 
anemia depends on its etiology. While IDA requires iron 
supplementation, thalassemia traits necessitate 
avoiding iron overload, which can exacerbate oxidative 
stress and organ damage. Misclassification can result in 
suboptimal or harmful interventions, highlighting the 
critical need for accurate differentiation of anemia types 
in clinical practice.16 As a readily available and cost-
effective parameter, the Mentzer Index has gained 
traction as a first-line screening tool for anemia in 
pregnancy. It is particularly useful in areas with limited 
access to advanced diagnostics, helping to distinguish 
between IDA and thalassemia traits. By enabling 
targeted management, the Mentzer Index contributes to 
better maternal and fetal health outcomes and reduces 
the burden of anemia in vulnerable populations.17 

Application of Mentzer Index in Pregnancy 

The Mentzer Index (MI) is calculated by dividing the 
Mean Corpuscular Volume (MCV) by the Red Blood Cell 
(RBC) count, both of which are components of routine 
complete blood count (CBC) tests. A Mentzer Index 
value greater than 13 suggests iron-deficiency anemia 
(IDA), while a value less than 13 indicates a likelihood of 
thalassemia trait. This simple formula enables 
healthcare providers to differentiate between these 
common causes of anemia without the need for 
specialized testing, making it particularly useful in 

prenatal care settings.18-19 In early pregnancy, anemia is 
often asymptomatic and may go undiagnosed until 
complications arise. Utilizing the Mentzer Index during 
routine antenatal visits allows for early detection of 
anemia etiology. Early identification of IDA enables 
timely iron supplementation, while recognition of 
thalassemia traits can prompt genetic counseling and 
further evaluation of fetal health. This proactive 
approach minimizes risks of adverse outcomes for both 
the mother and the fetus.20-21 The Mentzer Index is 
especially beneficial in low- and middle-income 
countries where advanced diagnostic tools, such as 
hemoglobin electrophoresis or genetic testing, may not 
be readily available. Its reliance on parameters from 
basic CBC tests makes it a cost-effective alternative for 
initial anemia screening. By streamlining the diagnostic 
process, MI ensures that limited healthcare resources 
are allocated efficiently, enabling better care for 
pregnant women.22-23 

Although the Mentzer Index is a valuable tool, its 
accuracy improves when used alongside other indices, 
such as red cell distribution width (RDW) and mean 
corpuscular hemoglobin (MCH). These parameters can 
help confirm the diagnosis and provide a more 
comprehensive understanding of the hematological 
profile. For instance, elevated RDW values are more 
indicative of IDA, while normal RDW with low MI 
strongly suggests a thalassemia trait.24 Despite its utility, 
the Mentzer Index is not infallible. Mixed anemia cases, 
such as IDA coexisting with thalassemia, can yield 
ambiguous MI results, complicating diagnosis. 
Moreover, the index relies on population-specific 
reference values for MCV and RBC, which may vary with 
ethnicity, altitude, and dietary habits. These factors 
necessitate caution in interpreting MI results, 
particularly in diverse populations.25 The application of 
the Mentzer Index in pregnancy significantly enhances 
maternal and fetal health outcomes by guiding 
appropriate interventions. Early and accurate diagnosis 
reduces risks associated with untreated anemia, such as 
preterm delivery, low birth weight, and postpartum 
complications. Additionally, the index supports better 
resource utilization by directing advanced testing and 
interventions to high-risk cases.26 

Limitations and Challenges 

1. Accuracy in Mixed Anemia Cases 

One of the significant limitations of the Mentzer Index 
(MI) is its reduced reliability in cases of mixed anemia, 
such as the coexistence of iron-deficiency anemia (IDA) 
and thalassemia traits. Mixed anemia can lead to 
intermediate Mentzer Index values, which do not clearly 
indicate either condition, complicating the diagnostic 
process. This challenge is particularly pronounced in 
populations with high prevalence rates of both IDA and 
hemoglobinopathies. 

2. Population-Specific Variability 

The effectiveness of the Mentzer Index depends on the 
accuracy of MCV and RBC reference ranges, which can 
vary significantly across different populations. Factors 
such as ethnicity, dietary habits, altitude, and genetic 



Emmanuel Ifeanyi Obeagu                                                                                                      Asian Journal of Dental and Health Sciences. 2025; 5(1):30-33 

[32]                                                                                                                                                                                                                                              AJDHS.COM 

predisposition influence these parameters, making it 
difficult to establish universal cutoff values. Without 
population-specific adjustments, there is a risk of false 
positives or negatives, potentially leading to 
misdiagnosis.24 

3. Limited Scope for Complex Anemias 

The Mentzer Index is a screening tool rather than a 
definitive diagnostic method. While it is useful for 
differentiating between IDA and thalassemia traits, it 
does not account for other anemia causes, such as 
vitamin B12 deficiency, folate deficiency, or anemia of 
chronic disease. Clinicians must rely on additional 
diagnostic tools to identify these conditions, reducing 
the standalone utility of MI.25 

4. Inaccuracy in Late Pregnancy 

Physiological changes in pregnancy, such as 
hemodilution and increased plasma volume, can alter 
hematological parameters, particularly in the second 
and third trimesters. These changes may skew the 
Mentzer Index values, making it less reliable in 
diagnosing anemia during late pregnancy. This 
limitation underscores the importance of interpreting 
MI results in the context of gestational stage and other 
clinical findings.26 

5. Dependency on Routine CBC Quality 

The reliability of the Mentzer Index hinges on the 
accuracy of CBC measurements, particularly MCV and 
RBC count. In settings with suboptimal laboratory 
practices or outdated equipment, errors in these 
parameters can lead to incorrect MI calculations and 
potentially flawed diagnoses. This is a significant 
concern in under-resourced healthcare facilities.27 

6. Lack of Consensus on Cutoff Values 

There is no universal agreement on the cutoff values for 
the Mentzer Index, with thresholds varying slightly 
across studies and guidelines. Some researchers 
advocate for a stricter cutoff (e.g., MI < 12 for 
thalassemia), while others suggest broader ranges. This 
lack of consensus adds to the complexity of its clinical 
application, requiring clinicians to consider local 
population data and their experience.27 

Conclusion 

The Mentzer Index stands as a simple, cost-effective, 
and accessible hematological tool for differentiating 
iron-deficiency anemia (IDA) from thalassemia traits, 
particularly in pregnant populations. Its reliance on 
basic complete blood count (CBC) parameters makes it 
an invaluable first-line screening method, especially in 
resource-limited settings. By facilitating early and 
accurate identification of anemia etiology, the Mentzer 
Index contributes to improved maternal and fetal 
outcomes, guiding appropriate interventions and 
preventing complications. 

Conflict of Interest: Author declares no potential 

conflict of interest with respect to the contents, 

authorship, and/or publication of this article. 

Source of Support: Nil 

Funding: The authors declared that this study has 

received no financial support. 

Informed Consent Statement: Not applicable.  

Data Availability Statement: The data supporting in 

this paper are available in the cited references.  

Ethics approval: Not applicable. 

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Emmanuel Ifeanyi Obeagu                                                                                                      Asian Journal of Dental and Health Sciences. 2025; 5(1):30-33 

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https://doi.org/10.29082/IJNMS/2023/Vol7/Iss3/543
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