MCH Test
Also known as: Mean Corpuscular Hemoglobin
What is MCH?
MCH (Mean Corpuscular Hemoglobin) measures the average amount of hemoglobin in each red blood cell. Hemoglobin is the protein that carries oxygen.[MedlinePlus (NIH)]
What This Test Measures
This test calculates the average weight of hemoglobin per red blood cell, measured in picograms (pg).[Cleveland Clinic]
Why It's Important
MCH helps diagnose and classify different types of anemia based on hemoglobin content per cell.[MedlinePlus (NIH)]
Low MCH often accompanies iron deficiency; high MCH may indicate B12 or folate deficiency.[Cleveland Clinic]
Who Should Get This Test?
MCH is routinely measured as part of a complete blood count when evaluating anemia.
Risk Factors
- Symptoms of anemia (fatigue, weakness, pale skin)
- Known iron deficiency or at risk for it
- Vegetarian or vegan diet
- History of malabsorption disorders
- Heavy alcohol consumption
- Taking medications affecting folate metabolism
- Family history of thalassemia
- Pregnant or planning pregnancy
Screening Schedule
Part of routine CBC; important when classifying type of anemia or monitoring treatment response.
What Happens During the Test
A blood sample is drawn from a vein. MCH is calculated automatically by the hematology analyzer by dividing hemoglobin by the red blood cell count.
Duration
5-10 minutes for blood draw; results typically available same day
Discomfort Level
Minimal discomfort from needle insertion
Risks & Side Effects
Standard blood draw with minimal risks.
- •Brief pain at needle site
- •Small bruise may develop
- •Rare: lightheadedness
- •Very rare: infection at puncture site
Normal Range
27 to 33 picograms (pg) per cell.
Note: MCH typically correlates with MCV results.
Source: MedlinePlus (NIH)Unit Conversion
Convert between pg (picograms) and fmol (femtomoles)
| pg (picograms) | fmol (femtomoles) |
|---|---|
| 25 | 1.55 |
| 27 | 1.68 |
| 30 | 1.86 |
| 33 | 2.05 |
| 35 | 2.17 |
High Values
High MCH can indicate macrocytic anemia, often caused by vitamin B12 or folate deficiency.[Cleveland Clinic]
Low Values
Low MCH indicates less hemoglobin per cell (hypochromic), often due to iron deficiency anemia or thalassemia.[MedlinePlus (NIH)]
Test Limitations & Accuracy
MCH interpretation has several considerations:
- ⚠MCH is calculated, not directly measured, so accuracy depends on hemoglobin and RBC count
- ⚠MCH generally parallels MCV - rarely provides unique diagnostic information
- ⚠High reticulocyte counts can elevate MCH (young cells are larger)
- ⚠Lipemia (fatty blood) can falsely elevate hemoglobin and MCH
- ⚠Cold agglutinins can affect red cell counting and MCH calculation
- ⚠Recent transfusion affects results
Alternative & Complementary Tests
MCH is interpreted alongside other red cell indices:
Primary measure of cell size; correlates with MCH
To assess hemoglobin concentration within cells
To measure variation in red cell size
To evaluate iron deficiency as cause of low MCH
When high MCH suggests macrocytic anemia
Frequently Asked Questions
What is the difference between MCH and MCHC?
MCH measures the average amount of hemoglobin per red blood cell (in picograms), while MCHC measures the average concentration of hemoglobin in red blood cells (as a percentage). Both help classify anemia.
Source: Cleveland ClinicReferences
Related Condition Guides
Medical Disclaimer
This information is for educational purposes only and is not intended as medical advice. Always consult with a qualified healthcare provider for interpretation of test results and medical decisions.
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