Unit Converter
MCH – Mean Corpuscular Hemoglobin
(Average Hemoglobin Content per Red Blood Cell - Key Marker in Anemia Classification)
Synonyms
- MCH
- Mean corpuscular hemoglobin
- Mean cell hemoglobin
- Hemoglobin per RBC
- Average RBC hemoglobin content
Units of Measurement
- pg
- pg/cell
- fmol
- fmol/cell
Key Unit Conversions
1 pg hemoglobin = 0.06207 fmol heme
(Hb molecular weight ≈ 64,500 Da; 1 molecule = 1 heme equivalent)
fmol=pg×0.06207\text{fmol} = \text{pg} \times 0.06207fmol=pg×0.06207 pg=fmol0.06207\text{pg} = \frac{\text{fmol}}{0.06207}pg=0.06207fmol
Examples
- 30 pg ≈ 1.86 fmol
- 25 pg ≈ 1.55 fmol
(pg/cell and fmol/cell are identical representations.)
Description
Mean Corpuscular Hemoglobin (MCH) represents the average amount of hemoglobin present in a single red blood cell.
It is calculated from:
MCH (pg)=Hemoglobin (g/dL)×10RBC count (millions/µL)\text{MCH (pg)} = \frac{\text{Hemoglobin (g/dL)} \times 10}{\text{RBC count (millions/µL)}}MCH (pg)=RBC count (millions/µL)Hemoglobin (g/dL)×10
MCH helps classify and interpret types of anemia and is part of the standard CBC indices:
- MCV (mean corpuscular volume)
- MCHC (mean corpuscular hemoglobin concentration)
- RDW
Physiological Role
Although MCH itself is an index and not a physiological substance, it reflects how much hemoglobin each RBC carries - critical for:
- Oxygen transport
- RBC color (chromicity)
- Detection of microcytic vs macrocytic anemias
Clinical Significance
HIGH MCH (Macrocytic / Hyperchromic pattern)
Typically occurs in macrocytic anemias, because RBCs are larger and contain more hemoglobin per cell.
Causes
- Vitamin B12 deficiency
- Folate deficiency
- Alcoholism
- Liver disease
- Hypothyroidism
- Myelodysplastic syndromes (MDS)
- Reticulocytosis (reticulocytes have higher MCH)
- Certain medications (hydroxyurea, antiretrovirals)
Pattern:
- High MCH
- High MCV
- Normal or low MCHC
LOW MCH
(Very common in practice)
Causes
- Iron deficiency anemia (most common)
- Thalassemia trait
- Anemia of chronic disease (late)
- Sideroblastic anemia
- Lead poisoning
Pattern:
- Low MCH
- Low MCV → microcytic cells
- Often low MCHC
Reference Intervals
(WHO + Tietz 8E + Mayo + ARUP)
Adults
- 27 – 33 pg
(≈ 1.68 – 2.05 fmol)
Children
Ranges differ by age:
| Age | MCH (pg) |
| Newborn | 31–37 |
| 2–6 months | 27–34 |
| 6 months–6 years | 24–30 |
| >6 years | 26–3 |
Diagnostic Uses
1. Anemia Classification
- Low MCH → microcytic anemia
- High MCH → macrocytic anemia
2. Differentiation of Microcytic Anemias
In iron deficiency vs thalassemia trait:
- IDA → low MCH + high RDW
- Thalassemia trait → very low MCH + normal RDW
3. Monitoring Treatment
- Iron therapy
- B12 and folate therapy
- Hematologic recovery
4. RBC Morphology Correlation
Helps confirm “hypochromic” or “hyperchromic” appearance on smear.
Analytical Notes
- Automated hematology analyzers calculate MCH from Hb and RBC count.
- Hemolysis, lipemia, or cold agglutinins may affect RBC or Hb values.
- MCH interpretation must be combined with MCV & MCHC.
- The index is average → severe anisocytosis may reduce accuracy.
Clinical Pearls
- Low MCH is the earliest change in iron deficiency.
- MCH helps distinguish thalassemia trait (very low MCH) from IDA.
- MCH rises earlier than MCV in reticulocytosis.
- Macrocytosis → both MCH and MCV increase simultaneously.
- MCHC differs — it represents concentration, while MCH is content per RBC.
Interesting Fact
MCH, MCV, and MCHC form a “triad” that allows clinicians to identify nearly every major anemia subtype even before looking at the peripheral smear.
References
- Tietz Clinical Chemistry & Molecular Diagnostics, 8th Edition - Hematology Indices
- WHO Hematologic Reference Ranges
- Mayo Clinic Laboratories - RBC Indices
- ARUP Consult - CBC Interpretation
- MedlinePlus / NIH - Hemoglobin & CBC Tests