---
title: "What does a high MCV mean?"
type: biomarker-interpretation
url: "https://www.test-well.com/biomarkers/mcv/high"
biomarker: MCV
direction: high
reference_range:
  - "age 18+: 80.0 – 100 fL"
reviewed_at: 2026-09-06
review_status: reviewed
date_published: 2026-09-05
---

# What does a high MCV mean?

> A high MCV (macrocytosis) means red cells are larger than normal. The common causes are vitamin B12 or folate deficiency, alcohol use, liver disease, hypothyroidism, certain medications (methotrexate, hydroxyurea, some HIV and anti-seizure drugs) and a high reticulocyte count after blood loss. It can precede anemia, so it's worth explaining even when hemoglobin is normal.


## What is the normal range for MCV?

- age 18+: 80.0 – 100 fL

Often reflects vitamin B12 or folate deficiency, alcohol use, or certain medications.

## What are the common causes of high MCV?

1. Vitamin B12 or folate deficiency
2. Alcohol use
3. Liver disease, hypothyroidism
4. Medications: methotrexate, hydroxyurea, zidovudine, valproate, some chemotherapy
5. Reticulocytosis (bone marrow responding to blood loss or hemolysis)
6. Myelodysplastic syndromes in older adults (less common)

## What symptoms go with high MCV?

- Often none
- Fatigue, tingling, memory issues if B12-related

## What do clinicians usually check next?

- Vitamin B12 and folate (methylmalonic acid for borderline B12)
- TSH and liver panel
- Reticulocyte count and peripheral smear
- Alcohol and medication review

Follow-up tests at TestWell: [TSH (Thyroid Stimulating Hormone)](https://www.test-well.com/tests/tsh) ($26.99), [TSH + Free T4](https://www.test-well.com/tests/tsh-with-free-t4) ($27.99), [Vitamin B12](https://www.test-well.com/tests/vitamin-b12) ($25.99), [Methylmalonic Acid (MMA)](https://www.test-well.com/tests/methylmalonic-acid) ($49.99), [Folate (Vitamin B9)](https://www.test-well.com/tests/folate) ($32.99).

## How do you recheck MCV?

| Test or panel | Type | Price | Fasting | Results |
| --- | --- | --- | --- | --- |
| [General Wellness Panel](https://www.test-well.com/tests/general-wellness-panel) | Panel (4 tests) | $89.99 | Yes | 1–3 business days |
| [Blood Clotting Panel](https://www.test-well.com/tests/blood-clotting-panel) | Panel (4 tests) | $149.99 | No | 3–7 business days |
| [Baseline Anemia Panel](https://www.test-well.com/tests/anemia-panel) | Panel (5 tests) | $74.99 | Yes | 2–4 business days |
| [CBC with Differential](https://www.test-well.com/tests/cbc-with-differential) | Test | $21.99 | No | 1–3 business days |

Plus one $6 lab processing fee per order; physician authorization included.

## Common questions

### Is a high MCV serious?

It's a clue, not a diagnosis. Most causes — B12, folate, alcohol, thyroid — are treatable; a persistently unexplained high MCV in an older adult gets a hematology look.

## Related

- [What does a low MCV mean?](https://www.test-well.com/biomarkers/mcv/low)
- [MCV reference ranges](https://www.test-well.com/biomarkers/mcv)
- [Hemoglobin reference range](https://www.test-well.com/biomarkers/hemoglobin)
- [Hematocrit reference range](https://www.test-well.com/biomarkers/hematocrit)
- [White Blood Cell Count reference range](https://www.test-well.com/biomarkers/white-blood-cell-count)

## Sources

- [AACC Lab Tests Online](https://www.testing.com/tests/red-blood-cell-indices/)

---

Medically reviewed by Youmna DiStefano, MD (Medical Reviewer, TestWell); last reviewed 2026-09-06. Review policy: https://www.test-well.com/editorial-policy

Canonical page: https://www.test-well.com/biomarkers/mcv/high
Machine-readable catalog: https://www.test-well.com/api/catalog.json · MCP server: https://www.test-well.com/mcp · Overview for agents: https://www.test-well.com/llms.txt

Prices are cash-pay, in USD, and include physician authorization; every order adds one flat $6 lab processing fee. Educational content is not a diagnosis — discuss results with a clinician.