Mean Corpuscular Hemoglobin (MCH)
How much hemoglobin, on average, each of your red blood cells carries.
AI-verified against cited sources. Awaiting expert reviewAlso called MCH, HCM, TCMHLOINC 785-6
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What it is
Mean corpuscular hemoglobin (MCH) is the average amount of hemoglobin in one red blood cell, measured in picograms (pg). Hemoglobin is the protein that carries oxygen. Your lab calculates MCH by dividing your total hemoglobin by your red blood cell count. It usually moves in step with MCV (cell size), because bigger cells have room for more hemoglobin.
Why it matters
MCH helps explain why hemoglobin or red cell counts might be low. Cells with too little hemoglobin look pale under a microscope. This is most often linked to low iron or to thalassemia trait, an inherited difference in hemoglobin that usually causes no symptoms. A high MCH usually goes along with large red cells. In pregnancy, screening programs use a low MCH as an early flag to look for thalassemia carrier status.
If it’s low
A low MCH means each red blood cell carries less hemoglobin than average, so the cells look pale under a microscope. This is called hypochromia. It usually goes along with a low MCV.
Common causes
- Low iron stores or iron deficiency anemia
- Thalassemia trait, an inherited difference in hemoglobin that usually causes no symptoms
- Long-term inflammation or chronic disease, in some people
- Slow blood loss, such as heavy periods or bleeding in the digestive tract, which can lead to low iron
- Lead exposure or less common blood conditions
What can help
- Ask whether a ferritin test (a measure of iron stores) is a good next step
- Tell your clinician about heavy periods, blood in your stool or black stools
- If you are pregnant or planning a pregnancy, ask whether thalassemia carrier screening applies to you. Some national screening programs follow up an MCH below 27 pg
If it’s high
A high MCH means each red blood cell carries more hemoglobin than average, usually because the cells are larger. It tends to travel with a high MCV. A clinician can look at it together with your hemoglobin and other results.
Common causes
- Larger red blood cells from low vitamin B12 or folate
- Regular alcohol use
- Some medicines, including some chemotherapy drugs
- Liver or thyroid conditions
- Sample effects, such as very cloudy (lipemic) plasma, cold agglutinins or red cells breaking down in the tube, which can make MCH read falsely high
- Bone marrow conditions (less common)
What can help
- Ask whether your MCV, vitamin B12 and folate results help explain it
- Ask whether the sample could have affected the result and whether a repeat test makes sense
- Review your medicines and supplements with your clinician or pharmacist
Usual ranges
What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.
For adults: 27–33 pg. Source: Parkview Health Laboratory, MedlinePlus, National Library of Medicine, Labcorp, ARUP Laboratories, Oregon Health & Science University Lab Services, NHS England (NHS Sickle Cell and Thalassaemia Screening Programme).
See MCH by age and sex, with the U.S. survey numbers where they exist.
How common is your level?
NHANES describes the US civilian, non-institutionalized population, not a 'healthy' reference group. People with disease, on medication, fasting or not (except fasting-subsample markers), smokers and so on are all included. A percentile says where a value sits among Americans of that sex and age, not whether it is normal.
Use the left and right arrow keys to read each age. Shift moves five years.
Reference data derived from CDC/NCHS National Health and Nutrition Examination Survey (NHANES), cycles 2015-2016, 2017-March 2020 (pre-pandemic), August 2021-August 2023. Analysis by bloodtesttracker.com; not endorsed by CDC, NCHS or HHS.
Explore MCH by age and sex: every percentile as a table, with a download.
What can affect your result
- Age: children and teenagers have different normal ranges, so adult ranges do not apply to them
- Sex: some labs print separate adult ranges for men and women, and many do not
- Ancestry: thalassemia trait, a common cause of low MCH, is more common in people with roots in Africa, the Mediterranean, the Middle East, India and Southeast Asia
- Pregnancy: iron needs go up, and a low MCH is used as a screening flag
- Iron, vitamin B12 and folate status
- Alcohol, some medicines and liver or thyroid conditions
- Cloudy plasma, cold agglutinins or sample handling can distort the result
- The analyzer used
- Very cloudy (lipemic) plasma can make the measured hemoglobin read falsely high, which pushes MCH up.
- Red cells breaking down in the tube can lower the red cell count and raise MCH.
- Cold agglutinins (red cells clumping in a cool sample) lower the red cell count, which can raise MCH.
- A recent blood transfusion mixes donor red cells with your own.
- Different analyzers can read the same blood slightly differently.
Weeks to a few months. Red blood cells live for roughly 3 to 4 months, so MCH shifts only as old cells are replaced.
When to talk to a clinician
An MCH slightly outside the range with a normal hemoglobin is usually something to bring up at a routine visit. Contact a clinician soon if your hemoglobin is also low (below 13 g/dL in men or 12 g/dL in women, the WHO anemia cutoffs), or if you have unusual tiredness, shortness of breath, pale skin or a fast heartbeat. If you are pregnant and your MCH is below 27 pg, mention it early so screening can be considered. Call 911 or your local emergency number for chest pain, fainting or severe shortness of breath.
Questions you could ask
- Has my MCH changed compared with my past results?
- How does my MCH fit with my hemoglobin and other blood counts?
- Does my MCH fit with my MCV and the rest of my blood count?
- Should we check my vitamin B12 and folate levels?
- Could the sample have affected this result?
- Should we check my ferritin or other iron tests?
Questions people ask
What is the difference between MCH and MCHC?
MCH is the amount of hemoglobin in the average red cell. MCHC is how concentrated that hemoglobin is, meaning the amount per volume of cell. A large cell can hold more hemoglobin (higher MCH) while the concentration stays normal.
Why does my MCH usually match my MCV?
Bigger cells have more room for hemoglobin, so MCH and MCV usually rise and fall together. Large cells tend to have a higher MCH and small cells a lower one.
Why do pregnancy screening programs look at MCH?
In England, the NHS screening program uses the MCH from the routine blood count as an early flag for thalassemia carrier status. An MCH below 27 pg leads to extra tests. It is a screening step and does not mean a person is a carrier.
Is MCH measured or calculated?
Calculated. The lab divides hemoglobin by the red cell count. If either of those is off, for example because of a cloudy sample, MCH will be off too.
Show the science and sources
Units
- 1 pg = 1 pg
- 1 pg = 0.06206 fmol
Is a change real?
MCH naturally varies about 0.85% from test to test in the same healthy person. Between two results from the same lab, a change of roughly 3% or more is unlikely to be day-to-day noise or lab variation (95% reference change value). Source: Systematic review and meta-analysis of within-subject and between-subject biological variation estimates of 20 haematological parameters (Coskun A et al., EFLM WG-BV).
For clinicians and researchers
MCH is calculated, not measured: MCH (pg) = Hb (g/dL) × 10 ÷ RBC (×10^6/µL). Because it is a ratio, any error in hemoglobin or red cell count carries into it. Lipemia can raise the measured Hb, and cold agglutinin clumping or in vitro hemolysis lowers the RBC count, so each can raise MCH. MCH tracks MCV closely, and MCH, MCV and MCHC should agree with each other as a quality check. Low MCH is the usual first screen for thalassemia trait. The NHS England antenatal screening handbook screens every pregnant woman for thalassaemia using MCH and treats an MCH below 27 pg as an action value (for example, the HbF action value is 5% below 27 pg and 10% at or above it, and partner screening for suspected alpha-chain variants applies below 27 pg). AAFP advises suspecting thalassemia in microcytic anemia with a normal or elevated ferritin. Some Dutch labs report MCH in fmol on the Hb monomer basis (16,114.5 g/mol), where 27–33 pg is about 1.7–2.0 fmol.
LOINC 785-6 (primary), 28539-5. Specimen: whole-blood.
Sources
- Complete Blood Count with Differential (Parkview Laboratory test directory), Parkview Health Laboratory
- RBC indices, MedlinePlus, National Library of Medicine
- Sample report, CBC, Platelet, No Differential (test 028142), Labcorp (2020)
- Sample report, CBC With Differential/Platelet (test 005009), Labcorp
- CBC with Platelet Count and Automated Differential (ARUP test 0040003), reference intervals effective March 1, 2021, ARUP Laboratories (2021)
- CBC with Differential: reference ranges (OHSU Lab Services test directory), Oregon Health & Science University Lab Services
- SCT screening: handbook for antenatal laboratories, NHS England (NHS Sickle Cell and Thalassaemia Screening Programme) (2024)
- Alpha- and Beta-thalassemia: Rapid Evidence Review, American Family Physician (2022)
- MCH: Mean Corpuscular Hemoglobin (conversion and formula reference), UnitsLab
- Answer to Case on Crazy CBC Values (cold agglutinin disease), The Blood Project
- How to handle lipemic CBC samples on Sysmex hematology analyzers?, Advances in Laboratory Medicine (2025)
- Assessment of Oxidative Stress Biomarkers in Rat Blood (states the hemoglobin monomer molar mass, 16,114.5 g/mol), Bio-protocol (2023)
- Evaluation of Macrocytosis, American Family Physician (2009)
- Measurement of Red Cell Lifespan and Aging, Transfusion Medicine and Hemotherapy (2012)
AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.