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Overview

What Is an MCH Blood Test?

An MCH blood test is a measurement included in a complete blood count (CBC). MCH, or mean corpuscular hemoglobin, estimates the average amount of hemoglobin in each red blood cell. Hemoglobin is the protein that carries oxygen. MCH is a calculated CBC value, so it does not diagnose a condition by itself.

How MCH relates to MCV and MCHC

MCH is calculated using the hemoglobin level and red blood cell measurements from the CBC. MCV describes the average size of red blood cells, while MCHC describes the average concentration of hemoglobin inside them. Clinicians interpret MCH in the context of these related results, the rest of the blood count, symptoms, and the laboratory’s reference range. This is the basic meaning of what is MCH in blood test reports and what is MCH in a blood report.

When It Is Needed

When Is an MCH Blood Test Needed?

MCH is usually measured as part of a CBC rather than ordered as a standalone test. A clinician may request a CBC when symptoms suggest anemia or another blood-related concern, or as part of a routine health evaluation. The test may help provide context for symptoms such as fatigue, weakness, pale skin, or shortness of breath.

  • Fatigue, weakness, dizziness, or shortness of breath may prompt a CBC that includes MCH.
  • Pale skin or other signs that may be consistent with anemia can lead to blood count testing.
  • A CBC may be used when a clinician suspects iron deficiency or another blood disorder.
  • Routine evaluations, pre-procedure checks, or monitoring of a known condition may also include a CBC.
  • Other CBC findings may lead a clinician to review MCH alongside hemoglobin and red blood cell measurements.

Preparation

How to Prepare for an MCH Blood Test

An MCH blood test generally requires no special preparation when it is collected as part of a CBC. However, other blood tests taken at the same appointment may require fasting or other instructions. Check with the ordering clinician or laboratory before the appointment so you know which instructions apply.

During the Test

What Happens During the MCH Blood Test?

An MCH blood test is usually a brief, single-session blood draw. A healthcare professional confirms your identity, cleans the skin, and inserts a needle into a vein, commonly in the arm. A small amount of blood is collected into a tube, then the needle is removed and pressure and a bandage are applied.

How the sample is analyzed

The laboratory analyzes the sample as part of the CBC and measures or calculates the MCH value. The report may list it with MCHC, MCV, hemoglobin, hematocrit, and red blood cell count. MCHC is a related measurement that describes hemoglobin concentration, while MCH estimates the average amount of hemoglobin per red blood cell.

Risks

Risks of an MCH Blood Test

  • Brief discomfort or a pinching sensation when the needle is inserted.
  • A small amount of bleeding after the needle is removed.
  • Bruising or mild tenderness at the collection site.
  • Lightheadedness or fainting during or shortly after the blood draw.
  • Rarely, an infection at the needle site.

After the blood draw

When to seek help

Contact a healthcare professional if bleeding does not stop with pressure, or if the site develops increasing redness, swelling, or severe pain. Seek medical advice after fainting, especially if you do not recover promptly or have another concerning symptom.

Results

Understanding MCH Blood Test Results

Your report gives a numeric MCH result, usually measured in picograms per cell. Use the reference interval printed by your own laboratory because ranges can vary between laboratories and testing methods. A result outside that interval is a reason to discuss the full CBC with a clinician, not a diagnosis by itself.

MCH resultWhat it may suggestHow it is evaluated
Low MCHRed blood cells may contain less hemoglobin on average; this can occur with iron deficiency or some microcytic patterns.The clinician reviews MCV, MCHC, hemoglobin, hematocrit, red blood cell count, symptoms, history, and possible follow-up tests.
Within the laboratory rangeThe average hemoglobin content is within that laboratory's stated interval.The result is still interpreted with the rest of the CBC and the reason the test was ordered.
High MCHRed blood cells may contain more hemoglobin on average, sometimes in patterns involving larger red blood cells.The clinician considers MCV and other CBC values, medical history, symptoms, and follow-up testing when needed.

Why MCH is read with other CBC values

MCH has more meaning when considered with MCHC, MCV, hemoglobin, hematocrit, and the red blood cell count. A low MCH may occur with iron deficiency or other small-cell patterns, while a high MCH may occur when red blood cells are larger than usual. These broad patterns do not identify the cause on their own. Symptoms, medical history, examination, and follow-up tests help explain an MCH blood test low, high, or otherwise unexpected result, as well as related findings such as low MCHC, high MCHC, or a low MCV blood test.

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