Mean Corpuscular Hemoglobin
MCH· also: Mean Cell Hemoglobin
Clinical Overview
MCH measures the average amount of hemoglobin contained in a single red blood cell, expressed in picograms (pg). It closely parallels MCV — when cells are larger, they usually contain more hemoglobin. MCH is used to classify anemia as hypochromic (low MCH) or normochromic.
Why This Test Matters
MCH provides complementary information to MCV in anemia classification. Hypochromic anemia (low MCH) alongside microcytosis (low MCV) strongly suggests iron deficiency. MCH trends over time are used to monitor response to iron therapy — MCH rises before hemoglobin does, making it an early marker of treatment response.
Reference RangesWHO/IFCC standards
| Age Group | Reference Range | Unit | Notes |
|---|---|---|---|
| Adults (18–64) | 27 – 33 | pg | — |
What Causes Abnormal Results?
High MCH Causes
- Macrocytic anemia (B12 or folate deficiency)
- Hereditary spherocytosis (hyperchromic cells)
- Cold agglutinins (laboratory artifact)
Low MCH Causes
- Iron deficiency anemia
- Thalassemia
- Anemia of chronic disease
- Lead poisoning
Signs & Symptoms to Watch For
How to Prepare for This Test
No special preparation. Automatically calculated from CBC parameters.
Factors That Can Affect Results
- Lipemia (high fat content in blood falsely raises measured hemoglobin, raising MCH)
- High WBC count (can affect spectrophotometric hemoglobin measurement)
Related Topics
Frequently Asked Questions
Is MCH the same as MCHC?
No. MCH is the absolute amount of hemoglobin per cell (in picograms). MCHC is the hemoglobin concentration relative to cell volume (g/dL). MCHC is more useful for detecting truly hypochromic cells. MCH is simpler and rises early in response to iron therapy, making it useful for monitoring treatment.
What causes a low MCH?
The most common cause of low MCH is iron deficiency, which reduces hemoglobin synthesis per cell. Thalassemia also causes low MCH, but in thalassemia the RDW is usually normal (all cells are uniformly small), whereas in iron deficiency the RDW is elevated (cells vary in size). Ferritin and hemoglobin electrophoresis help distinguish between these two conditions.