Patient Report: MCV at Lower Limit of Normal – Possible Microcytosis / Thalassemia?

By SWA

Finding:

A Mean Cell Volume (MCV) of 83 fL is at the lower limit of the normal range (83–103 fL). This means the patient’s red blood cells are slightly smaller than average. While this alone does not confirm disease, it can suggest microcytosis (small red blood cells), which is often linked to certain types of anemia.

MCV (Mean Corpuscular Volume)

If Genetic Thalassemia is Absent

If the patient does not have genetic evidence of thalassemia (e.g., no mutations detected by 23andMe in common beta thalassemia genes), they may still have other HBB gene mutations not included in that testing.

About Thalassemia:
Thalassemia is a group of inherited blood disorders affecting the production of hemoglobin, the oxygen-carrying protein in red blood cells. It is caused by mutations in genes (such as HBB) that produce the globin chains of hemoglobin.

  • Beta Thalassemia Major: Caused by two defective copies of the HBB gene; typically results in severe anemia.

  • Beta Thalassemia Minor / Trait: One defective copy; usually asymptomatic or mild anemia.

Microcytosis – Cleveland Clinic

Chapter18 – Thalassemia

Other Possible Causes of Low MCV (Microcytosis)

  1. Iron Deficiency Anemia – The most common cause. Occurs when iron levels are insufficient for adequate hemoglobin production.

  2. Anemia of Chronic Disease – Chronic illnesses can affect iron utilization and red blood cell production.

  3. Sideroblastic Anemia – A rare group of disorders where bone marrow cannot properly incorporate iron into hemoglobin.
    Microcytic Anemia – Sideroblastic causes

  4. Lead Poisoning – Lead interferes with heme synthesis, reducing hemoglobin production.
    Lead poisoning and microcytosis%20are%20rare%20and%20require%20specialized%20testing.)

  5. Other Conditions – Certain liver diseases and less common disorders can also lower MCV.

Possible Symptoms of Slightly Low MCV

  • Fatigue and weakness

  • Shortness of breath

  • Pale skin

  • Rapid heartbeat

  • Specific to cause: e.g., pica in iron deficiency anemia

Key Considerations

  • MCV alone cannot confirm a diagnosis. It must be interpreted alongside other lab results and the patient’s history.

  • Persistent low MCV should prompt further evaluation to determine the underlying cause.

Summary:
An MCV of 83 fL sits at the lower end of normal and may indicate microcytosis. Causes include iron deficiency anemia, chronic disease, sideroblastic anemia, lead poisoning, and thalassemia. Even if standard genetic testing (like 23andMe) shows no beta thalassemia mutations, undetected variants can still be present. Symptoms may be mild or absent but can include fatigue, pale skin, and rapid heartbeat. Diagnosis requires looking beyond MCV to a full blood panel and patient history.

Further connective information:

Elevated Erythrocyte Count (Erythrocytosis/Polycythemia): Causes, Diagnosis, and Relationship with MCV and Liver Enzymes
https://swaresearch.blogspot.com/2025/05/elevated-erythrocyte-count.html

Is GENE THERAPY implanting new genes or demethylating existing genes?
https://swaresearch.blogspot.com/2023/10/is-gene-therapy-implanting-new-genes-or.html

Hemochromatosis Iron Overload
https://swaresearch.blogspot.com/2023/12/hemochromatosis-iron-overload.html

 

© 2000-2025 Sieglinde W. Alexander. All writings by Sieglinde W. Alexander have a fife year copy right. Library of Congress Card Number: LCN 00-192742 ISBN: 0-9703195-0-9

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