Blood DiseasesCancer

ANEMIA: What causes it and why.

Anemia is a disorder almost always associated with some disease or condition that has serious implications. When you’re anemic there are a myriad of reasons why, and many of them are not good. It is considered a symptom or finding accompanying some other greater problem.

To be anemic one has either to have lost a volume of blood from the body or have a significant underproduction or destruction of red blood cells and hemoglobin. Defining anemia is easy. It is a deficiency in the oxygen-carrying components of the blood. Those components are red blood cells and hemoglobin, the protein to which oxygen molecules bind to be circulated through the body. All body tissues need oxygen to function properly and red blood cells and hemoglobin are the body’s couriers. In anemia, something causes a lower-than-normal amount of hemoglobin and number of red blood cells.

Red blood cells (RBC’s) are produced mostly by the bone marrow, but also, to a lesser degree, by the spleen.

When doctors investigate a patient for anemia, the first test done is a Complete Blood Count (CBC). This test measures the number of RBC’s in the blood, the amount of hemoglobin present, and the hematocrit, the percentage of RBC’s in the blood. Also determined microscopically are the Red Blood Cell Indices (MCV, MCH, MCHC)* which measure the specific size and amount of hemoglobin in each RBC. So the doctor knows from the indices if each RBC is too large, too small, too pale and lacking hemoglobin, or too dense and too full of hemoglobin. These numbers help determine the type of anemia and thus lead doctors to the cause.

There are anemias where the RBC’s are too small—called Microcytic anemia.

There are anemias where the RBC’s are too large—called Macrocytic anemia.

There are anemias where the RBC’s lack hemoglobin—called Hypochromic anemia.

There are anemias where the RBC’s have excess hemoglobin—called Hyperchromic anemia

There are anemias comprised of combinations of these types.

Each of these four categories describe the state of the RBC’s and points toward finding the specific cause of the anemia.

As mentioned at the onset, anemias occur because something causes an under-production of RBC’s, something causes the body to lose RBC’s, or something destroys RBC’s. Finding which of these is occurring is essential to determining the cause, and to begin appropriate treatment. According to one reference, “there are more than 400 types of anemia.” So finding the type requires some investigation. In addition to the CBC, determination of iron, Vitamin B-12, and folic acid levels in the blood, evaluation of the bone marrow, and direct microscopic examination of RBC’s (a peripheral smear) are done. Feces and urine may be examined for traces of blood. Hemoglobin may be examined by electrophoresis to determine if it is abnormal in its makeup.

*MCV stands for “Mean Corpuscular Volume” — Volume (size) of each RBC

MCH stands for “Mean Corpuscular Hemoglobin” — amount of hemoglobin in each RBC

MCHC stands for “Mean Corpuscular Hemoglobin Concentration” — density (concentration) of hemoglobin in each RBC

There are some Hereditary Anemias genetically-inherited at birth.

Three main types are:

Sickle-cell Anemia —seen largely in African-Americans and Hispanic Americans, the

RBC’s rapidly break down, clog arteries, block oxygen from getting to tissues.

Thalassemia —seen largely in people of Mediterranean, African, Middle Eastern, or

Southeast Asian origin. RBC’s cannot mature and function inefficiently.

Aplastic Anemia —rare, inherited malfunctioning bone marrow causes decreased

production of RBC’s (and WBC’s as well).

Far more common are Anemias caused by BLOOD LOSS. Bleeding from the stomach, small intestine or colon are most often the cause. This results in a deficiency of iron and RBC’s.

Examples of Blood Loss Anemia:

Bleeding Ulcer

Gastric Erosion from NSAID Overuse

Bleeding from Colon Cancer


Excessive Menstruation

Abnormal Vaginal Bleeding

Excessive Urinary Bleeding

In all of these situations, the rate of blood leaving the body exceeds the rate at which new RBC’s are produced causing low RBC and hemoglobin levels, ie. Anemia.

Anemias caused by the Underproduction of RBC’s are common as well.

Examples are:

Iron deficiency—inadequate intake of iron in one’s diet

Pernicious anemia—inadequate intake of Vitamin B-12

Folic Acid anemia—inadequate intake of folic acid

Sickle cell anemia—inherited underproduction of RBC’s

Bone marrow suppression*

Anemias caused by the Destruction of RBC’s are also called Hemolytic Anemias. The rate of RBC destruction exceeds the rate of new RBC production causing low RBC and hemoglobin levels.

Examples are:

Sickle Cell Anemia

Exposure to chemical toxins

Autoimmune disorders

Enlarged Spleen—traps and destroys RBC’s

Artificial Heart Valves, vascular grafts—RBC’s are damaged by being traumatized by


Bone marrow suppression can be inherited (aplastic anemia, Thalassemia) or acquired as in the case of chemotherapy, radiation therapy, lead poisoning, or other drug exposure—external factors suppress RBC and WBC production. Leukemia and Myelofibrosis are cancerous disorders that suppress bone marrow.

If anemia comes on quickly, as in sudden blood loss, the patient will have symptoms. In those patients whose anemia develops gradually, symptoms may be mild or even absent. They acquire a tolerance for the anemia and adjust to the lower levels of Oxygen-carrying elements.

Fatigue, shortness of breath, lightheadedness, weakness, irregular or rapid heart rate, headache, chest pain, or cold hands and feet may be mild or not occur, but are easily recognized by patients with acute blood loss.

Treatment, of course, is determined by the cause found. Taking iron and multivitamins won’t work for everybody. Nor will shots of B-12. Treatment specific to the cause is what’s needed. In a lot of cases, transfusions of RBC’s are the best choice. Specifics of treatment will not be covered is this post for brevity’s sake, but one must remember, anemia is a symptom or physical finding that usually indicates something serious is going on with the patient.

Treatment can seem futile in cases such as Anemia of Chronic Disease. Patients with cancer, AIDS, Chronic Kidney Disease, Crohn’s Disease, or some auto-immune disorders will be anemic and no treatment has any affect on it. Anemia is purely an accompaniment of the chronic disease; it’s part of it. It’s important to know that so you don’t have the patient taking unnecessary iron or getting ineffective B-12 shots. Fortunately, this type of anemia usually never worsens to the level of requiring blood transfusion.

Dr. G’s Opinion: In Family Medicine, anemia is a weekly occurrence. Patients have a CBC for some reason and are accidentally found to be anemic. The physician has a professional obligation, then, to find out why. After thorough history and physical examination, including testing the feces for blood, a lab work-up is begun. The results of initial blood work may lead to other, less common, diagnostic tests. The final outcome may be something never suspected, but the doctor must persist until he has an answer. Just prescribing iron supplements is shirking your responsibility to the patient and is poor medicine.


Personal knowledge/experience of William Gilkison MD

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