MCH and MCHC on a Blood Test, Explained

MCH and MCHC sit next to MCV on a complete blood count and are routinely confused with each other. They describe two different things about the hemoglobin inside a red blood cell, and they are not equally useful.

What is the difference between MCH and MCHC?

Both are calculated rather than measured directly, from the hemoglobin, hematocrit, and red cell count.

	Full name	What it describes	Typical units
MCH	Mean corpuscular hemoglobin	The amount of hemoglobin in an average red cell	picograms (pg)
MCHC	Mean corpuscular hemoglobin concentration	How concentrated that hemoglobin is within the cell	g/dL

The distinction is mass versus concentration. A larger cell can hold more hemoglobin in total (higher MCH) while being no more densely packed than a smaller one (unchanged MCHC).

Why does MCH usually tell you nothing new?

Because bigger cells hold more hemoglobin. MCH tracks cell size closely, so it tends to move in the same direction as MCV and for the same reasons.

If MCV is high, MCH is usually high. If MCV is low — as in iron deficiency — MCH is usually low. Clinically the pair is described together as microcytic-hypochromic or macrocytic, and the underlying question is almost always the one MCV already raised.

MCH is largely a restatement of cell size. MCHC is the index that can say something size does not — which is also why it is the one most often flagged for a reason that has nothing to do with the patient.

What does a high MCHC mean?

MCHC typically runs around 32 to 36 g/dL. Unlike the other indices, it has a hard ceiling: hemoglobin cannot be packed indefinitely into a fixed volume, so genuinely high values are uncommon and meaningful.

Two explanations dominate, and they are very different.

A laboratory artefact. This is the more common cause. MCHC is calculated from hemoglobin and hematocrit, so anything that falsely raises measured hemoglobin or falsely lowers hematocrit pushes it up. Hemolysis in the sample, lipemia, cold agglutinins, and very high white cell counts all do this. The result is a flagged number that describes the specimen, not the person.

Hereditary spherocytosis. When a high MCHC is real, this is the classic cause. In spherocytosis the red cell membrane loses surface area, the cell becomes spherical, and hemoglobin ends up more densely concentrated inside a smaller volume. Elevated MCHC is common enough in this condition that automated red cell indices have been studied specifically as a screening tool for it.

Why the calculation matters

Neither index is measured. Both are derived, and knowing the arithmetic explains most of their odd behaviour:

MCH = hemoglobin ÷ red cell count
MCHC = hemoglobin ÷ hematocrit

MCH divides by cell number, so it inherits whatever the count does. MCHC divides by hematocrit — the proportion of blood volume occupied by red cells — which is itself derived on most modern analysers from the red cell count and MCV.

That chain is the reason MCHC is the fragile one. It sits at the end of two calculations, so an error anywhere upstream propagates into it. A sample that has partially hemolysed releases hemoglobin into the plasma: the analyser still measures that hemoglobin, but the cells it came from no longer contribute to hematocrit. Numerator up, denominator down, MCHC flagged high — with nothing having changed in the patient.

What about a low MCHC?

More common and less specific. It generally accompanies the same hypochromic picture as a low MCH — most often iron deficiency, where cells are both smaller and less densely filled.

Frequently asked questions

What is a normal MCHC level?

Roughly 32 to 36 g/dL, with variation by laboratory. Compare against the range printed on your own report.

What does high MCHC mean on a blood test?

Most often a problem with the sample rather than with you — hemolysis, lipemia, or cold agglutinins can all falsely raise it. When the value is genuine and persists on a repeat draw, hereditary spherocytosis is the classic explanation and warrants proper evaluation.

Is a high MCHC dangerous?

The number itself is not the danger. It is a prompt to establish whether the result is real. A repeat sample resolves most cases; a persistently high MCHC is a specific finding a clinician should work up.

What is the difference between MCH and hemoglobin?

Hemoglobin is the total concentration in your blood. MCH is the average amount inside a single red cell. You can have normal total hemoglobin with abnormal MCH if cell number and cell content are compensating for each other.

Should I track MCH or MCHC over time?

Neither has outcome data supporting use as a personal health metric. They are diagnostic supporting indices, interpreted alongside MCV, RDW, and the rest of the count — see what is actually worth tracking.

The takeaway

Of the three red cell indices, MCV does most of the work, MCH largely echoes it, and MCHC is the one that occasionally says something the others cannot.

The practical rule for MCHC is to suspect the specimen before suspecting the patient. A high value is more often hemolysis, lipemia, or a cold agglutinin than a red cell disorder — and a repeat draw is usually the fastest way to find out. When it persists, it points somewhere specific, which is unusual on a panel where most flags are non-specific.