What is anemia?

Anemia is a condition defined by deficiency of hemoglobin in the blood. Hemoglobin is a protein molecule contained in red blood cells and is responsible for carrying oxygen. The normal level of hemoglobin in the blood is approximately 12-14 grams per deciliter in men and 11-13 gm/dl in women, although normal value ranges may vary slightly among different laboratories.

Anemia can occur rapidly when there is a sudden loss of blood. Often, the source of this blood loss can be from the esophagus, stomach, or small intestines. This is often seen as vomiting blood (hematemesis) or rectal bleeding. Patients usually feel dizzy because their blood pressure drops, especially when standing up.

Anemia occurs more chronically when the body does not produce enough hemoglobin or red blood cells to maintain its normal level.

What causes anemia?

By far, the most common cause of anemia is shortage of iron. Iron is essential to make new red blood cells. In women, this is usually due to menstrual loss of blood.

Other possible causes of anemia could include:

a slow loss of blood in the GI tract that cannot be seen in a person's stool
deficiencies of vitamin B12 for which a special substance in the stomach is needed in order for the vitamin to be absorbed from food
major stomach surgery that may cause an inability to absorb proper nutrients, such as B-vitamins
folic acid deficiency (also referred to as folate deficiency), which is when a person's body does not get enough folic acid
There are other less common causes of anemia. It can be seen in patients with a chronic disease (such as severe arthritis, inflammation, etc.), in which the red blood-forming tissues (blood marrow) become sluggish. There are specific diseases of the bone marrow in which all of the main blood cells are not made efficiently or adequately.


Mild chronic anemia does not usually cause significant symptoms. More severe anemia, however, will result in:

  • an unhealthy, pale appearance of the skin (pallor)
  • a lack of energy
  • shortness of breath

Other symptoms, based on the cause of the anemia, may also be present. Patients with bone marrow problems may have inadequate white blood cells and platelets, whereas patients with hemolysis may develop yellow jaundice of the skin and eyes.


Tests for anemia are simple and logical. Blood levels of hemoglobin are measured and the red blood cells are observed under a microscope to assess the likely cause of the condition.

Red blood cells have characteristic appearances according to the specific deficiency. It is possible to recognize very "young" red blood cells, called reticulocytes. More than the usual number of these in the blood indicates a rapid turnover of red blood cells in response to hemolysis or blood loss.

Assessment of the other blood constituents (white cells and platelets) will demonstrate whether the problem is solely due to hemoglobin development, or a more diffuse bone marrow disease. The lack of iron can be recognized easily on a blood smear, and the levels can be measured. Blood levels of iron, folate, and B12 are measured when appropriate. When discovered, further investigations can determine the precise cause of any deficiency.

The finding of iron deficiency anemia, particularly in women who are not menstruating and men, should prompt the investigation for chronic bleeding into the bowel. This bleeding may not be obvious to the patient, but can be detected by tests on the stool.

These then lead logically to examination of the lining of the intestine to seek a source for the bleeding. These are most commonly found in the stomach and colon using standard endoscopic techniques such as:

These investigations are particularly important in older patients since this bleeding is an important early sign of possible gastrointestinal cancer.

Capsule Endoscopy

In some people, a source of bleeding can not be found in the esophagus, stomach or colon. These people may need further evaluation of their small intestines for bleeding. This can now be accomplished vis the swallowing of a small capsule with a camera in it that can take pictures from within the small intestines and transmit them to a recorder that the patient wears on a belt. These pictures can then be reviewed by a physician for areas of bleeding that can not be reached by standard endoscopes.


Some treatment options include:

  • iron supplements, usually given by mouth, for iron deficiency anemia
  • iron infusions, given by injection, for more severe cases of iron deficiency anemia
  • vitamin B12 infusions
  • stricter diet and nutrition management for cases of folic acid deficiency