ovarian cancer Stages and Treatment

 Pernicious anemia

(Vitamin B12 deficiency (by malabsorption), Addison's anemia, Congenital pernicious anemia)

Description

Blood circulates throughout the body and performs a number of essential functions. It provides oxygen, carries away carbon dioxide and transports the nutrients essential to sustaining life. In addition, by serving as a vehicle for messengers that act at a distance such as hormones, the blood helps the various parts of the body to communicate with each other. It is the blood cells, working in concert with the liquid part of the blood (the plasma ), which performs these important tasks. Most of the cells that make up blood are red blood cells ( erythrocytes ). Blood also contains white blood cells ( leukocytes), although their number is less important. Their role is to defend the body against foreign bodies – including bacteria, viruses and fungi.

Anemia occurs when the blood does not contain enough hemoglobin (a compound of iron and protein in red blood cells that carry oxygen) or there are not enough red blood cells. When the lack of red blood cells is caused by vitamin B12 deficiency, it is called pernicious anemia . The term pernicious was adopted many years ago, when there was no effective treatment for this disease which was then inevitably fatal. There are excellent treatments available these days and the majority of people lead normal lives with very few side effects.

Pernicious anemia can affect all racial groups, but is more common in fair-skinned people, especially those of Scandinavian or northern European ancestry. It usually does not appear before the age of 30, although there is a juvenile form. About 4% of Canadians have insufficient levels of vitamin B12.

Other names for pernicious anemia are vitamin B12 deficiency (due to malabsorption), Addison's anemia and congenital pernicious anemia.

Causes

Pernicious anemia is caused by a deficiency in vitamin B12, a vitamin necessary for the normal production of red blood cells. It is often hereditary. Risk factors include a history of autoimmune endocrine diseases , a family history of pernicious anemia, and Scandinavian or Northern European ancestry.

The meat and dairy products we eat are our main sources of vitamin B12. However, pernicious anemia is not simply caused by insufficient consumption of these foods, except in strict vegetarians. It is usually due to a failure in the complex process of vitamin B12 absorption in the digestive tract.

For vitamin B12 to be absorbed in the small intestine, the cells that line part of the stomach must produce a substance called intrinsic factor . This substance binds to vitamin B12 and the two are absorbed together in the lower part of the small intestine ( ileum), just before the junction between the small intestine and the large intestine (or colon). If the ileum has been damaged or removed during surgery, the intrinsic factor-vitamin B12 combination is not absorbed. Often people with conditions like Crohn's disease, for example, have part of the ileum (the part of the small intestine that absorbs vitamin B12) removed. These people should be tested for possible vitamin B12 deficiency, and treated if necessary.

Lack of intrinsic factor can also be congenital (present at birth). Juvenile or congenital pernicious anemia usually manifests before the age of three. It is believed that in the congenital form, it is enough for only one parent to carry the gene to transmit the disease to the child.

Less common causes of decreased vitamin B12 absorption include chronic pancreatitis , malabsorption syndrome, certain medications, and very rarely, accelerated vitamin B12 metabolism due to long-standing hyperthyroidism . The elderly absorb vitamin B12 contained in food less well, which explains why they are more often affected by vitamin B12 deficiency.

Pernicious anemia is also often associated with certain autoimmune endocrine (glandular) diseases including type 1 diabetes, hypoparathyroidism , Addison's disease and testicular dysfunction.

Certain antacids and medications used to treat heart conditions and diabetes can contribute to vitamin B12 deficiency.

Symptoms and Complications

In most cases, there are no early signs of pernicious anemia. As the disease progresses, shortness of breath and decreased exercise tolerance may occur. Sometimes the heartbeats quicken and are more noticeable. People with pernicious anemia often have very low hemoglobin levels, but few of the symptoms that this causes, such as fatigue. Their levels of white blood cells (cells to fight infection) and platelets (cells needed for blood clotting and stopping bleeding) may also drop. However, infections and bleeding disorders rarely occur in pernicious anemia. Other possible symptoms are:

• abdominal pain;
• paleness of the skin;
• a sore, shiny tongue;
• poor appetite and weight loss;
• tingling and numbness in the hands and feet;
• unsteadiness in gait and loss of balance (especially in the dark);
• mental status changes, including memory loss, irritability, mild depression, and dementia;
• blindness of the yellow-blue color system.

If left untreated, vitamin B12 deficiency can gradually affect sensory and motor nerves and cause neurological problems. Anemia can also affect the digestive and cardiovascular systems, causing inflammation of the tongue, impaired sense of smell, bleeding gums and loss of deep tendon reflexes. In very severe cases, it sometimes causes paranoia, delirium and mental confusion.

Pernicious anemia is a chronic disease that progresses slowly and steadily. In the past, when the disease was little known and there was no treatment, this anemia eventually led to death, after long years of suffering. Today, the prognosis is excellent. The administration of vitamin B12 supplements in the required amount cures the deficiency and allows the person to lead a normal life.

If this anemia progresses for a long time before being detected, it risks causing damage to certain parts of the body, mainly the nervous system and the digestive system. Polyps sometimes form in the stomach, which increases the risk of stomach cancer. It is worth noting that a vitamin B12 deficiency will alter the appearance of epithelial cells in the cervix; thus, in an untreated woman, a Pap test could give a false positive result.

Diagnosis 

Common symptoms will likely prompt a doctor to order various tests for anemia. One of these tests will measure the concentration of vitamin B12 in the blood. The blood will then be examined under a microscope to assess the size and shape of the red blood cells. In cases of pernicious anemia, these blood cells will be larger and fewer in number than normal.

If tests reveal low levels of vitamin B12 in your blood, your doctor may order additional tests to confirm that your body has sufficient levels to support normal cellular processes. Rarely is a bone marrow test used to confirm the diagnosis.

Previously, the Schilling test was part of the diagnostic approach, but it is no longer necessary in current practice.

Stomach cancer is more common in people with pernicious anemia. The physician should follow up on all clinical findings (eg, presence of symptoms, positive stool blood test result) suggesting possible gastrointestinal involvement. He may prescribe additional tests, such as X-rays or endoscopy (an examination of the inside of the body with a device equipped with a flexible tube).

Treatment and Prevention

The amount of vitamin B12 retained by the body is directly proportional to the amount administered. The main treatment for this type of anemia is vitamin B12 injections. It is sometimes difficult to calculate the dose of vitamin B12 required, because this dose must also restore the reserves of the vitamin in the liver.

At first, between 5 and 7 injections are given over a short period. The effect of this treatment usually begins to be felt within 48 to 72 hours; which should eliminate the need for a blood transfusion. Later, the injections will be given once a month and they will undoubtedly have to continue indefinitely. Maintenance treatment with very high doses of vitamin B12 (0.5 mg to 2 mg per day) taken orally makes injections superfluous.

Pernicious anemia cannot be treated without the supervision of a doctor. Nevertheless, a well-balanced diet is essential to provide the other elements that are necessary for the formation of healthy blood cells, including folic acid, iron and vitamin C.

Treatment with vitamin B12 should be continued for life, unless the cause of the deficiency can be corrected.