Macrocytic anemia: when erythrocytes are larger than normal

Macrocytic anemia is a type of anemia characterized by the presence of abnormally large red blood cells. These large cells lack the necessary nutrients to function properly.

Anemia is defined as a condition involving a reduced number of healthy or normal red blood cells, a decreased concentration of hemoglobin in the blood, or a hematocrit value (normal ranges are between 41% and 53% in men, and between 36% and 46% in women) that is lower than normal.

Red blood cells are the most abundant cells in the blood, and their main function is to capture oxygen and transport it to various tissues throughout the body. This function is performed through hemoglobin, their primary protein, which binds oxygen to iron atoms, allowing its transport via the bloodstream. Consequently, anemia causes difficulties in oxygen distribution to all the body’s cells, as the decrease in red blood cells leads to this disruption.

The most common forms of macrocytic anemia:

• Megaloblastic macrocytic anemia: often caused by vitamin B12 or vitamin B9 deficiency, leading to the production of many immature red blood cells that die quickly
• Non-megaloblastic macrocytic anemia: usually caused by other medical conditions that impair nutrient absorption

Characteristic symptoms of macrocytic anemia:

• Diarrhea or constipation
• Fatigue, lack of energy, or dizziness when standing or exerting effort
• Loss of appetite
• Pale skin
• Irritability
• Concentration problems
• Shortness of breath, especially during exercise
• Swelling and redness of the tongue or bleeding gums

The main risk factors for macrocytic anemia are deficiencies in vitamins B12 and B9. Therefore, the risk factors for these deficiencies also apply to this type of anemia. These factors include:

• Advanced age
• Surgical removal of the stomach or small intestine
• Inflammatory diseases of the small intestine
• Autoimmune diseases, such as Graves’ disease or vitiligo

Other risk factors for macrocytic anemia include:

• Myelodysplastic syndrome: a group of disorders that affect blood cell production in the bone marrow
• Alcoholism: excessive alcohol consumption can lead to vitamin B12 deficiency
• Hypothyroidism: can cause macrocytic anemia due to disruptions in the metabolism of vitamins B12 and B9

Blood tests commonly used to diagnose macrocytic anemia include:

• Complete blood count (CBC): this test provides information about hemoglobin levels and other important parameters for this type of anemia, such as mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC), as well as other blood characteristics
• Peripheral blood smear: examines blood cells under a microscope
• Reticulocyte count: measures the number of immature red blood cells (reticulocytes) in the bone marrow

Other tests may include measurements of iron, vitamin B12, and folate in red blood cells. Thyroid-stimulating hormone (TSH) and free thyroxine (free T4) may also be tested to determine if thyroid dysfunction is causing macrocytic anemia.

Treatment for macrocytic anemia focuses on addressing the underlying condition causing it. For example, if the anemia is due to vitamin B12 and B9 deficiencies, it can be treated with supplements.

Macrocytic anemia depends on various factors and is therefore very difficult to prevent.

However, maintaining a varied and balanced diet that includes foods rich in vitamins B12 and B9 may help reduce the risk of developing macrocytic anemia.