Contributed by-Healthians Team
What is MCH test?
MCH stands for mean corpuscular haemoglobin. An MCH value refers to the average quantity of haemoglobin present in a single red blood cell. Haemoglobin is the protein in your red blood cells that transports oxygen to the tissues of your body. Your MCH value is related to two other values, mean corpuscular volume (MCV) and means corpuscular haemoglobin concentration (MCHC). MCH test checks the average amount of haemoglobin per unit volume of red blood cells.
Who should get tested?
This test is performed with a CBC test that measures the different cells that make up your blood, including your:
- Red blood cells
- White blood cells, which fight infection
- Haemoglobin
- Platelets, which help your blood clot
Your doctor may order a CBC test as part of your yearly physical exam or to check for disease. Your doctor might recommend an MCH test if you have symptoms of a condition that affects your blood cell count. Those who have symptoms of anaemia, they get an MCH test as per the doctor’s prescription.
When you have iron-deficiency anaemia and if you have these symptoms, your doctor may order this MCH test.
- Weakness
- Tiredness
- Pale or yellow skin
- Trouble catching your breath
- Dizziness
- Fast or abnormal heartbeat
- Chest pain
- Headache
Why is the MCH test needed?
Anaemia can cause abnormal MCH readings on blood tests. Often a lack of iron causes anaemia with a low MCH. Your body needs iron to make haemoglobin. Pregnancy, blood loss, and weight loss surgery can cause a drop in your iron levels and lead to iron-deficiency anaemia or low haemoglobin and MCH levels.
Since the MCHC is done as part of a CBC, the test is done any time a CBC is ordered. For example, this may include routine health screenings or during the diagnosis, treatment, and follow-up of a wide range of medical conditions.
Reasons a doctor may specifically look at the MCHC include:
- When symptoms of anaemia are present, such as fatigue, pale skin, or light-headedness
- When looking for the different causes of anaemia
If you have anaemia due to folate deficiency, you could experience the following additional symptoms:
- Diarrhoea
- Decrease in appetite
- Irritability
- A smooth or sensitive tongue
What does MCH test results mean?
MCH is calculated by dividing the amount of haemoglobin in a given volume of blood by the number of red blood cells present. The normal range for MCH is between 27.5 and 33.2 picograms (pg).
An MCH value calculated below 27.5 pg is considered low MCH. This means that there’s a low amount of haemoglobin present per red blood cell.
A low MCH value typically indicates the presence of iron deficiency anaemia. In more rare cases, low MCH can be caused by a genetic condition called thalassemia. In this condition, the production of haemoglobin is limited. This means there aren’t as many red blood cells circulating in your bloodstream.
If you have a low MCH value, you may experience the following symptoms:
- Shortness of breath
- Chest pain
- Fast heartbeat
- Fatigue or weakness
- Very pale or yellowish skin
- Headache
An MCH value calculated above 33.2 pg is considered high MCH. This means that there is a larger amount of haemoglobin present per red blood cell.
High MCH value can often be caused by anaemia due to a deficiency of B vitamins, particularly B-12 and folate. You can experience the same symptoms as you feel in low MCH levels. If you have anaemia that’s due to B-12 deficiency, you may also experience:
- Prickling sensation in your hands or feet
- Nausea or vomiting
- Bloating and gas
- Depression or confusion
How is the test done?
Your doctor needs your blood sample to perform this test. The lab technician will insert a needle into a vein in your arm or hand and draw a small sample of blood. This sample will then be tested in a laboratory. There are no preparations needed for this test. However, if it is being performed along with other tests, then you may have to fast for several hours before the sample collection. You should inform your doctor about any pre-existing medical conditions or medicines you might be on as they can influence your test results.
