Iron Deficiency Anemia

Iron is an essential mineral for the production of hemoglobin, a protein that carries oxygen throughout our body. Iron deficiency anemia is the most common type of anemia in the world. Its cause is iron deficiency in the body.

Foods most rich in iron
Foods most rich in iron

Relationship between iron and anemia

Red blood cells, also called red blood cells or erythrocytes, are the blood cells responsible for transporting oxygen. They are the red blood cells that pick up oxygen inspired by the lungs and carry it to every cell in our body.

We call it anemia when the concentration of red blood cells is reduced.

The main component of the red cell is hemoglobin, a protein that needs iron to be formed. When iron deficiency occurs in the body, there is a lack of raw material for the formation of hemoglobin and, consequently, for the formation of red blood cells. The inability to produce red blood cells causes anemia.

Therefore, every time the body's iron stores are low, we develop iron deficiency anemia or iron-deficiency anemia.

Iron metabolism

The body controls its iron stocks accurately, keeping it steady at all times. When we have the complete stock, the intestine stops absorbing the iron from the food, letting it be excreted in the stool. If iron levels fall, the small intestine again absorbs iron from food, replenishing our supplies.

The iron absorbed in the intestine is stored in the liver, "packaged" in a protein called ferritin. When we have low levels of ferritin, it means our iron stores are low. Generally, of the total amount of iron in our body, half stays inside the red blood cells and half is stored in the form of ferritin. There is still a small fraction linked to transferrin, a protein that transports the iron from the stores to the bone marrow where the new red blood cells are produced.

Generally, healthy adults do not need too much iron in the diet because the iron already present in the body is constantly being recycled. When a red cell becomes old and is destroyed (more or less 120 days old), its iron is taken up by transferrin and taken back to the bone marrow, being reused in the formation of a new red cell. Therefore, it takes many years with a low iron absorption so that there is a deficiency in body stores.

The great risk of iron-poor diet is in those individuals who are in need of more iron than they do in inventories.

Two examples that are easy to understand are children and pregnant women. The first group is constantly growing and thus requiring increasing amounts of iron. Children ages 6 months to 3 years are the most likely to develop iron deficiency because they are in high demand and have not yet had time to build their stocks.

Pregnant women generally have good iron stores, but they spend it quickly on the formation of a new being. In these two groups, an iron-rich diet is essential to keep stocks at adequate levels.


a) Diet

As already explained, a simple iron deficiency in the diet is currently a rare cause of iron deficiency anemia in healthy adults. The diet of most people contains enough iron to compensate for the small losses that occur over time.

Except for people with malnutrition due to lack of food, there is no need to worry about diet, since most meats have enough iron. Even vegetarians are able to ingest good amounts of iron, since foods like spinach, eggs, cream of wheat, beans and cereals contain enough iron.

b) Malabsorption

Iron deficiency and iron deficiency anemia may occur in patients with diseases of the gastrointestinal tract that prevent the absorption of iron chronically, as in cases of atrophic gastritis or celiac disease. These patients may ingest up too much iron but can not absorb it, preventing them from replenishing their supplies when needed.

c) Blood loss

The main cause of iron deficiency anemia is blood loss. When we lose blood, we lose the iron that was inside the hemoglobins, forcing the organism to use its stocks in the production of new red blood cells.

When bleeding is visible, such as in cases of vomiting with blood, blood in the stool (eg, major causes of gastrointestinal bleeding) or trauma with bleeding, for example, the cause of anemia becomes obvious as there are losses large volumes of red blood cells.

In these cases, there is even a great loss of iron, but the cause of the anemia is an immediate loss of blood, without any time for the body to produce more red blood cells. Women with very heavy menstrual periods may also develop iron deficiency anemia.

Iron deficiency anemia is more difficult to identify when there are small bleeds, but steadily. These pictures are common in stomach ulcers, bowel tumors and hemorrhoids.

Often the patient does not even notice the presence of blood in the stool. The amount of blood lost is small to cause immediate anemia, but in the long run causes the body to always be using its iron stores to compensate for the erythrocytes lost in bleeding. In these cases, the amount of iron in the diet may be less than that needed to replenish the stores, causing the patient to exhaust his reserves and develop iron deficiency anemia over time.

Therefore, presently, any iron deficiency anemia, unless there is an obvious cause, should indicate the investigation of a source of occult bleeding.


The symptoms of iron deficiency anemia are the same as those of any anemia: fatigue, pallor of the skin, shortness of breath, exercise intolerance, tachycardia (fast heart).

However, iron deficiency anemia can cause some symptoms that are not common in other anemias, such as appetite perversion (also called pica), which is the desire to eat non-food such as ice, earth, paper, concrete, etc.

Restless leg syndrome is also a common finding. Another typical sign of iron deficiency anemia is the presence of very red urine after ingestion of beet.


The diagnosis of anemia is made when the values of hemoglobin and hematocrit (percentage of red blood cells) are below the reference value:

In general, we say that there is anemia when:
  • hematocrit is less than 41% in men or 35% in women
  • hemoglobin less than 13 g/dL in men or 12 g/dL in women

Once the diagnosis of anemia is established, its cause must be identified. On the blood count, in addition to the drop in hematocrit and hemoglobin, MCV and HCM are usually low in iron deficiency anemia. Following the investigation of anemia, the amount of iron in the blood, ferritin and transferrin saturation should be measured. If these values are low in the presence of anemia, it can be said that there is iron deficiency anemia.

If there are no obvious causes for iron deficiency anemia (pregnancy or visible bleeding), an investigation usually begins with tests to look for hidden bleeding from the digestive tract, such as digestive endoscopy and colonoscopy.


Treatment of iron deficiency anemia is done with iron replacement. Ferrous sulfate tablets usually have up to 6x more iron than we get on a normal diet. If iron deficiency anemia is caused by pregnancy or by a stronger menstrual flow, iron replacement is usually sufficient.

Iron is best absorbed if taken fasting and along with vitamin C or orange juice. Iron replacement may cause some side effects, the most common being nausea and heartburn. Stools with a very dark coloring are also common, but this is only an aesthetic question, without major clinical relevance.

If the cause of iron deficiency anemia is not clear, one should not only replace iron, one must also investigate the cause. Prescribing iron without conducting an investigation of hidden bleeds may even temporarily correct anemia but will not treat the underlying disease. If the cause is a tumor of the intestine, for example, just replacing iron, without going looking for the source of the blood loss, will delay the diagnosis, reducing the chances of curative treatment of the lesion.

Iron rich food

Although diet is important, people with iron deficiency often need more iron than they can consume through their diet.

In a normal 2000 calorie diet, there is an average of about 10 mg of elemental iron. Already a single ferrous sulfate tablet 325 mg contains 65 mg of elemental iron.

Therefore, increasing dietary iron intake is not usually recommended as the sole treatment for iron deficiency anemia. This does not mean, however, that a diet rich in iron can not help. The more iron the patient can consume in their diet, the less the need to replace iron with supplements.

In general, the foods most rich in iron are:
  • Red meat
  • Egg yolk
  • Fish meal
  • Dark green leaves such as spinach and kale
  • Dried fruits such as plums and raisins
  • Cereals and grains fortified with iron (check the labels)
  • Mollusks (oysters, clams and scallops)
  • Kids of turkey or chicken
  • Beans, lentils, peas and soy beans
  • Liver
  • Artichokes

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