Mean Corpuscular Hemoglobin
Also written as: MCH
The average amount of hemoglobin inside each individual red blood cell.
What it measures
The average amount of hemoglobin, the oxygen-carrying protein, contained in a single red blood cell. It is not measured directly - the analyzer calculates it by dividing the total hemoglobin by the red cell count.
Why a doctor orders it
It comes automatically with every complete blood count. Clinicians use it together with red cell size (MCV) to sort anemias into broad categories, which helps point toward a cause such as low iron or low vitamin levels.
What is generally associated with a higher result
Broadly associated with larger-than-average red cells, a pattern seen with vitamin B12 or folate shortage, heavy alcohol use, and some thyroid conditions. It can also be pushed up artificially by very fatty blood samples or by cold-reacting antibodies that clump cells in the tube.
What is generally associated with a lower result
Broadly associated with smaller, paler red cells, classically from iron shortage or from inherited hemoglobin traits such as thalassemia trait, a common and often harmless carrier state.
Everyday things that move this number
Not every shift in a value reflects disease. These are ordinary factors known to affect this particular measurement:
- A fatty meal before the draw, which can cloud the sample and skew the hemoglobin reading
- Delays between blood draw and analysis
- Cold-reacting antibodies that clump cells in the tube, a lab artifact
- Anything that affects the red cell count itself, since MCH is a calculation
Questions to take to your appointment
- Is this being read together with MCV and RDW, the other red cell measurements?
- Could a sample issue, like a fatty sample, have affected this calculated value?
- Would iron studies or vitamin levels help explain the pattern you are seeing?
Build a printable questionnaire with your own results →
Where to read more
MedlinePlus, from the US National Library of Medicine, publishes patient-facing pages on individual lab tests and is a reliable next stop: medlineplus.gov/lab-tests .
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