Microcytosis

Microcytosis means your red blood cells are smaller than normal. It is a finding from a routine blood test, not a disease itself. Red blood cells carry oxygen throughout your body, and if they are too small, they may not carry enough. This often points to an underlying health condition, most commonly iron deficiency.

What is Microcytosis?

Microcytosis is a medical term indicating that your red blood cells are smaller than their typical size. This condition is usually discovered during a routine blood test called a complete blood count (CBC). It is a sign that points to an underlying health issue, rather than being a disease on its own.

Your body's red blood cells are vital for carrying oxygen from your lungs to every part of your body. When these cells are smaller than normal, they are called microcytic (my-kroh-SIT-ik) red blood cells. This smaller size can affect their ability to transport enough oxygen, potentially leading to symptoms like tiredness or weakness. Doctors identify microcytosis by measuring the average size of your red blood cells. This measurement is called the mean corpuscular volume (MCV). If your MCV is below the normal range, it indicates that your red blood cells are microcytic. This finding prompts further investigation to discover why your cells are small. Microcytosis itself does not cause symptoms. Instead, any symptoms you experience are due to the underlying condition causing your red blood cells to be small. For example, if the cause is a lack of iron, you might feel very tired.

Common causes

Microcytosis is most often caused by conditions that affect your body's ability to make healthy red blood cells or hemoglobin, the protein inside them that carries oxygen. The most common reason is not having enough iron (iron deficiency anemia). Other causes include inherited blood disorders and certain long-term illnesses.

The most frequent cause of microcytosis is iron deficiency anemia. This happens when your body does not have enough iron to produce hemoglobin, the crucial protein in red blood cells that binds to oxygen. Without enough iron, red blood cells become smaller and paler. Causes of iron deficiency can include blood loss (such as from heavy menstrual periods or gastrointestinal bleeding), poor iron absorption, or not getting enough iron from your diet. Another common cause is thalassemia (thal-uh-SEE-mee-uh), which is an inherited blood disorder. People with thalassemia make an abnormal form of hemoglobin, leading to smaller, fewer, and often fragile red blood cells. The severity of thalassemia varies widely, from mild forms that cause no symptoms to severe forms requiring regular blood transfusions. Anemia of chronic disease, also known as anemia of inflammation, can also lead to microcytosis. This type of anemia occurs with certain long-term illnesses, such as cancer, kidney disease, or inflammatory conditions like rheumatoid arthritis or Crohn's disease. These conditions can interfere with the body's ability to use iron effectively or produce enough red blood cells. Less common causes of microcytosis include sideroblastic anemia, a rare group of disorders where the body cannot properly use iron to make hemoglobin, and lead poisoning. In these cases, the body has iron, but it cannot be incorporated into red blood cells correctly, leading to small cells.

When it's serious

While microcytosis itself is a finding, the underlying conditions causing it can be serious if left untreated. You should seek medical attention if you experience symptoms like extreme fatigue, shortness of breath, dizziness, or pale skin. These signs suggest your body might not be getting enough oxygen.

Microcytosis is a signal that your body needs attention. If the underlying cause, such as anemia, is not treated, it can lead to more severe health problems over time. For adults, prolonged anemia can strain the heart, potentially leading to heart problems. In children, untreated anemia can affect growth and development. Pregnant individuals with untreated anemia may face complications during pregnancy. It is important to pay attention to symptoms that suggest your red blood cells are not effectively delivering oxygen. These "red flag" signs include feeling unusually tired or weak, experiencing shortness of breath even with light activity, feeling dizzy or lightheaded, or noticing that your skin is paler than usual. Other signs can include cold hands and feet, brittle nails, or headaches. You should contact your doctor if you notice any of these symptoms. Your doctor can order blood tests, such as a complete blood count (CBC) and iron studies, to determine the exact cause of your microcytosis. Early diagnosis and treatment of the underlying condition can prevent more serious complications and improve your overall health. Do not try to self-diagnose or treat microcytosis, as the wrong treatment for certain conditions (like taking iron supplements for thalassemia) can be harmful.

Related conditions

Microcytosis is not a condition itself, but rather a sign of an underlying health issue. The "related conditions" are actually the specific diseases or disorders that cause your red blood cells to be smaller than normal. Identifying these conditions is key to understanding and treating microcytosis effectively.

When a doctor finds microcytosis on your blood test, it means they need to investigate further to find the specific related condition. The most common related condition is iron deficiency anemia. This occurs when your body lacks sufficient iron, which is essential for producing hemoglobin. Without enough hemoglobin, red blood cells are smaller and less efficient at carrying oxygen. Another significant related condition is thalassemia. This is a group of inherited blood disorders where the body produces an abnormal type or insufficient amount of hemoglobin. Depending on the specific type and severity, thalassemia can lead to varying degrees of microcytosis and anemia. It is crucial to distinguish thalassemia from iron deficiency, as treatments differ significantly. Anemia of chronic disease is also a related condition. This type of anemia develops in people with long-term inflammatory conditions, infections, or diseases like cancer or kidney failure. The inflammation can interfere with how the body uses iron and produces red blood cells, often resulting in microcytosis. Rarer related conditions include sideroblastic anemia, where the body has iron but cannot incorporate it into hemoglobin correctly, and lead poisoning. Lead poisoning can damage the bone marrow, where red blood cells are made, leading to microcytosis and anemia. Each of these conditions requires specific diagnostic tests and tailored treatment approaches.

Frequently asked questions

What is the normal range for MCV?

The normal range for mean corpuscular volume (MCV) can vary slightly between laboratories, but it is generally between 80 and 100 femtoliters (fL). If your MCV is below 80 fL, it indicates microcytosis, meaning your red blood cells are smaller than normal. Your doctor will interpret your specific results.

Can microcytosis be cured?

Microcytosis itself is a finding, not a disease, so it cannot be "cured" directly. However, the underlying condition causing microcytosis can often be treated or managed. For example, if it's due to iron deficiency, iron supplements can resolve it. If it's due to an inherited condition like thalassemia, it can be managed with specific medical care.

Do I need to take iron supplements if I have microcytosis?

You should only take iron supplements if your doctor determines that iron deficiency is the cause of your microcytosis. Taking iron supplements when you don't need them, especially if you have conditions like thalassemia, can be harmful and lead to iron overload. Always consult your doctor before starting any supplements.

Is microcytosis always a sign of something serious?

Microcytosis is not always a sign of something immediately life-threatening, but it always indicates an underlying health issue that needs investigation. The seriousness depends on the cause. For instance, mild iron deficiency is common and treatable, while some forms of thalassemia or chronic diseases can be more serious if left unmanaged.

How is microcytosis diagnosed?

Microcytosis is first identified through a routine complete blood count (CBC) test, which measures the size of your red blood cells (MCV). If microcytosis is found, your doctor will likely order further tests, such as iron studies, hemoglobin electrophoresis, or genetic testing, to pinpoint the exact underlying cause.

Can diet help with microcytosis?

Diet can play a role if your microcytosis is caused by iron deficiency. Eating iron-rich foods like red meat, poultry, fish, beans, lentils, and fortified cereals can help. However, diet alone may not be enough to correct significant iron deficiency, and supplements might be needed. Diet does not treat microcytosis caused by other conditions like thalassemia.

Sources

• MedlinePlus — Microcytosis
• Mayo Clinic — Microcytosis
• Cochrane Library — Microcytosis