Microcytic anemia: Types, Causes, Symptoms, Diagnosis, Treatment Perspectives and Prevention

It is defined as reducing the size of red blood cells below normal levels.

Anemia is a prevalent condition that is widespread in the human population.

Circulating red blood cells (RBCs) contain a protein known as hemoglobin; that protein has four polypeptide chains and a heme ring that contains iron in reduced form.

Iron is the main component of hemoglobin and is the primary carrier of oxygen. The decrease in iron reserves in the body affects the production of hemoglobin, which subsequently hampers the transport of oxygen to the body’s organ systems.

Anemia reduces the oxygen-carrying capacity of the blood and leads to tissue hypoxia. It is usually diagnosed by hematocrit (the proportion of red blood cells packed in blood volume) and hemoglobin concentration.

As the name suggests, hypochromic microcytic anemia is anemia in which circulating red blood cells are smaller than the average size of red blood cells (small cells) and have a diminished red color (hypochromic).

The most common cause of this type of anemia is decreased body iron stores due to multiple reasons.


This may be due to decreased iron in the diet, poor absorption of iron from the intestine, loss of acute and chronic blood, and increased demand for iron in certain situations, such as pregnancy or recovery from trauma or surgery. Higher.

An adult human requires 1 mg to 2 mg per day of iron. The typical western diet contains approximately 10mg to 20mg of iron.

Iron from animal sources is found in the form of Heme iron, which has a bioavailability of 10% to 20% compared to non-heme iron, with a limited bioavailability of 1% to 5%.

The cause of the low bioavailability of non-heme iron is due to its interaction with tannins, phosphates, and other food constituents. An average male contains 6 grams of iron, while a female includes 2.5 grams.

This diet is usually enough to maintain a healthy iron group. Ingested iron is released from other food components by the gastric juice, while ascorbic acid (vitamin C) prevents the precipitation of ferric.

Subsequently, the iron is absorbed from the duodenum and the upper parts of the jejunum through a so-called iron transporter (ferroportin). At the same time, the transferrin protein transports this iron to the blood.

Iron is stored in the form of ferritin, a ubiquitous iron protein found predominantly in the liver, spleen, bone marrow, and skeletal muscles. In the liver, it is stored in parenchymal cells, while in other tissues, it is stored in macrophages.

This absorption process of iron from the intestine is controlled by hepcidin, a protein that regulates the amount of iron absorbed by the diet. Hypochromic microcytic anemia is caused by any factor that reduces the body’s iron stores.

Hemoglobin is a globular protein that is a significant component of red blood cells and is manufactured in the bone marrow by erythroid progenitor cells.

It has four globin chains, two of which are alpha globin chains. The other two are beta-globin chains; these four chains are linked to the porphyrin ring (heme), whose center contains iron in ferrous iron (iron reduced), able to bind four oxygen molecules.

Reduced iron stores stop the production of hemoglobin chains, and their concentration begins to decrease in newly formed red blood cells.

Since the red color of red blood cells is due to hemoglobin, the color of newly formed red blood cells begins to fade, so its name is hypochromic.

As the newly produced red blood cells contain less hemoglobin, they are relatively small than normal red blood cells, so their name is tiny.

Hypochromic microcytic anemia due to iron deficiency is caused due to the interruption of iron supply in the diet due to the decrease in the iron content in the diet, pathology in thin intestines such as chronic diarrhea, gastrectomy, and vitamin C deficiency in the diet.

It may be due to acute or chronic blood loss and a sudden increase in the demand for pregnancy or significant trauma and surgery.

The reduction of hemoglobin in red blood cells decreases the amount of oxygen administered to peripheral tissues and leads to tissue hypoxia.

The decrease in the amount of hemoglobin in the red blood cells leads to a compromised size of the red blood cells.

Normal red blood cells contain a central area of ​​whiteness that is generally one-third the size of red blood cells; however, in hypochromic microcytic anemia, this size increases, and hemoglobin is usually only present in the peripheral border of red blood cells.

The average size of RBC is approximately 80 to 100 femtoliter / red blood cells (fl / red blood cells); however, in iron deficiency anemia, this size decreases below 80 fl / red blood cells.

The iron stored in the normal bone marrow gives a blue-black color in the reaction with the Prussian blue dye. Still, in hypochromic microcytic anemia, the stainable iron decreases markedly or is absent in severe cases.

Poikilocytes in the form of small, elongated red blood cells (pencil cells) are also characteristically observed.

The typical story indicates:

  • Reduction of iron intake in the diet.
  • Increased blood loss in the menstrual flow.
  • Bleeding of git, particularly of gastric and duodenal ulcers.
  • Malignancy or large intestine.
  • Major trauma, after which the iron reserves are depleted.

The patient may also have complained of food trapped inside the chest due to esophageal networks and a swollen tongue (glossitis); Together with anemia, a Plummer-Vinson syndrome is defined as a rare manifestation of iron deficiency.

In the physical examination, a patient can present evident pallor in the hands and conjunctivitistachycardia, increase in the respiratory rate, exhaustion, and koilonychia (spoon-shaped nails).

Severe anemia can also lead to the production of signs and symptoms of angina due to reduced oxygen delivery to cardiac myocytes.

The first test to perform is a complete blood count (red blood cells) that will indicate the presence of anemia after a thorough physical examination. CBC will show different indices of red blood cells as mean corpuscular volume and mean corpuscular hemoglobin concentration.

These parameters comment on the amount of hemoglobin within the red blood cells; both generally decrease in the hypochromic microcytic anemia.

The first test to perform is the complete blood count (CBC), which will indicate the presence of anemia after a thorough physical examination.

The complete blood count will show different rates of red blood cells as mean corpuscular volume and mean corpuscular hemoglobin concentration.

These parameters comment on the amount of hemoglobin within the red blood cells; both generally decrease in hypochromic microcytic anemia. The next test is iron studies that examine transferrin saturation, total iron-binding capacity, and ferritin.

Total iron-binding capacity usually increases in iron deficiency anemia, while transferrin saturation is markedly reduced in iron deficiency anemia.

Ferritin levels below 12 ng/ml in the absence of scurvy are a reliable indicator of iron deficiency anemia.

However, a low or average ferritin level does not exclude the diagnosis of iron deficiency anemia because ferritin is an acute-phase reactive protein. Its level increases during the time of infections.

As iron levels decrease, transferrin levels increase in compensation.

The peripheral smear will show red blood cells of small size with pencil cells. The microcytic cells will have a large area of ​​central pallor and a small peripheral border of hemoglobin.

After establishing the diagnosis of hypochromic microcytic anemia, iron replacement therapy can be started. The treatment includes 325mg of ferrous sulfate three times a day orally.

Up to 10 mg of iron can be absorbed from the intestine and is the preferred initial treatment. Nausea and constipation are the side effects that limit compliance with this therapy.

Compliance can be increased by gradually increasing the treatment dose while monitoring the patient’s side effects. The maximum tolerated amount is usually selected to replace lost iron.

The impact of this treatment usually appears after three weeks, while the full effects will be evident at two months. Parenteral iron products can be used when:

  • Oral drugs produce relentless side effects.
  • Anemia is resistant to oral therapy.
  • There is some gastrointestinal disease that prevents the adequate absorption of iron.
  • There is a continuous loss of blood that can not be corrected with oral supplements.

The iron preparation with sorbitol is infused slowly for 5 minutes at a dose of 50 mg/kg of body weight in men and 35 mg/kg in women. The parenteral dose is usually the deficit of iron plus an extra gram of iron to replenish the body’s iron reserves.

The differential diagnosis of hypochromic microcytic anemia can be thalassemias, anemia due to chronic diseases, lead poisoning, and sideroblastic anemia linked to the X chromosome.

Microcytosis is a term used to describe red blood cells that are smaller than usual. Anemia is when you have few numbers of red blood cells that work correctly in your body.

In microcytic anemias, your body has fewer red blood cells than usual. The red blood cells that you have are also too small. Several different types of anemias can be described as microcytic.

Microcytic anemias are caused by conditions that prevent your body from producing enough hemoglobin. Hemoglobin is a component of your blood. It helps carry oxygen to your tissues and gives your red blood cells their red color.

Iron deficiency causes most microcytic anemias. Your body needs iron to produce hemoglobin. But other conditions can also cause microcytic anemia. To treat microcytic anemia, your doctor will first diagnose the underlying cause.


You may not notice any symptoms of microcytic anemia at first. Symptoms often appear at an advanced stage when the lack of normal red blood cells affects their tissues.

Common symptoms of microcytic anemias include:

  • Fatigue, weakness, and fatigue.
  • Loss of resistance
  • Difficulty breathing.
  • Dizziness.
  • Pale skin.

If you experience any of these symptoms and do not resolve them within two weeks, request an appointment to see your doctor.

You should schedule an appointment to see your doctor as soon as possible if you experience severe dizziness or difficulty breathing.

Types and causes of microcytic anemia

Microcytic anemias can be further described according to the amount of hemoglobin in red blood cells. They can be hypochromic, normochromic, or hyperchromic:

  1. Hypochromic microcytic anemias

Hypochromic means that red blood cells have less hemoglobin than usual. The low hemoglobin levels in the red blood cells make it look paler. In microcytic hypochromic anemia, your body has low levels of red blood cells that are smaller and paler than usual.

The majority of microcytic anemias are hypochromic. Hypochromic microcytic anemias include:

Iron deficiency anemia: The most common cause of microcytic anemia is iron deficiency in the blood. Iron deficiency anemia can be caused by:

  • Inadequate intake of iron is usually a result of your diet.
  • It can not absorb iron due to celiac disease or Helicobacter pylori infection.
  • Chronic blood loss due to frequent or heavy periods in women or gastrointestinal (GI) hemorrhages of upper gastrointestinal ulcers or irritable bowel syndrome.
  • The pregnancy.

Thalassemia: Thalassemia is a type of anemia caused by a hereditary anomaly. It involves mutations in the genes necessary for the average production of hemoglobin.

Sideroblastic anemiaSideroblastic anemia can be inherited due to genetic mutations (congenital).

It can also be caused by a condition acquired later in life that impedes your body’s ability to integrate iron into one of the components necessary to produce hemoglobin.

This results in an accumulation of iron in your red blood cells. Congenital sideroblastic anemia is usually microcytic and hypochromic.

  1. Anemias microcíticas normocrómicas

Normochromic means that your red blood cells have average hemoglobin, and the red tone is not too pale or deep. An example of normochromic microcytic anemia is:

Anemia of inflammation and chronic disease: anemia due to these conditions is usually normochromic and normocytic (red blood cells are standard size). The normochromic microcytic anemia can be observed in people with:

These conditions can prevent red blood cells from functioning normally. This can lead to less absorption or utilization of iron.

  1. Hyperchromic microcytic anemias

Hyperchromic means that red blood cells have more hemoglobin than usual. Your red blood cells’ high hemoglobin levels make them a more intense red color than usual.

Congenital spherocytic anemia: hyperchromic microcytic anemias are rare. They can be caused by a genetic condition known as congenital spherocytic anemia.

This is also called hereditary spherocytosis. In this disorder, the membrane of your red blood cells does not form correctly. This makes them rigid and has an inadequate spherical shape. They are sent to decompose and die in the spleen because they do not travel properly in the blood cells.

  1. Other causes of microcytic anemia

Other causes of microcytic anemia include:

  • Toxicity of lead.
  • Copper deficiency.
  • Excess zinc causes copper deficiency.
  • Consumption of alcohol.
  • The consumption of drugs.


Microcytic anemias are often detected for the first time after your doctor has ordered a blood test called a complete blood count (CBC) for another reason.

If your CBC indicates that you have anemia, your doctor will order another peripheral blood smear test. This test can help detect early small cell or microcytic changes in your red blood cells.

Hypochromia, normochromic, or hyperchromic can also be observed with the peripheral blood smear test.

Your primary care doctor can refer you to a hematologist. A hematologist is a specialist who works with blood disorders. They may be able to diagnose better and treat the specific type of microcytic anemia and identify its underlying cause.

Once a doctor has diagnosed you with microcytic anemia, tests will be done to determine the cause of the condition. They can perform blood tests to detect celiac disease. They can evaluate their blood and stool to see for bacterial H. pylori infection.

Your doctor may ask about other symptoms you have experienced if you suspect that chronic blood loss is the cause of your microcytic anemia. They can refer you to a gastroenterologist if you have stomach or other abdominal pain.

A gastroenterologist could perform imaging tests to look for different conditions. These tests include:

  • Abdominal ultrasound
  • Upper GI endoscopy (EGD).
  • Computed tomography of the abdomen.

For women with pelvic pain and long periods, a gynecologist may look for uterine fibroids or other conditions that could cause more intense flow.

Treatment of microcytic anemia

The treatment for microcytic anemia focuses on treating the underlying cause of the disease.

Your doctor may recommend that you take iron and vitamin C supplements. Iron will help treat anemia, while vitamin C will help increase your body’s ability to absorb iron.

Your doctor will focus on diagnosing and treating the cause of blood loss if acute or chronic blood loss causes or contributes to microcytic anemia. Women with iron deficiency in painful periods may be prescribed hormone therapy, such as birth control pills.

In microcytic anemia so severe that you are at risk for complications such as heart failure, you may need to receive a blood transfusion from the donor’s red blood cells. This can increase the number of healthy red blood cells your organs need.


Treatment can be relatively simple if simple nutrient deficiencies cause microcytic anemia. As long as the underlying cause of the anemia can be treated, the anemia itself can be treated and even cured.

In very severe cases, untreated microcytic anemia can become dangerous. It can cause tissue hypoxia. This is when the tissue is deprived of oxygen. It can cause complications that include:

  • Low blood pressure is also called hypotension.
  • Coronary artery problems.
  • Lung problems.
  • Strokes

These complications are more common in older adults who already have lung or cardiovascular diseases.


Getting the best iron in your diet is the best way to prevent microcytic anemia. Increasing your vitamin C intake can also help your body absorb more iron. You may also consider taking a daily iron supplement.

These are often recommended if you already have anemia. It would help if you always talked to your doctor before starting any supplement. You can also try to get more nutrients through your food. Foods rich in iron include:

  • Red meat.
  • Poultry.
  • Beans.
  • Dried fruits like raisins and apricots.

Foods rich in vitamin C include:

  • Citrus fruits, especially oranges and grapefruit.
  • Kale.
  • Red peppers.
  • Brussels sprouts.
  • Strawberries
  • Broccoli.