The Separate - But Overlapping - Root Causes of Anemia

Wed, 12 Oct. 2011 - 9:34 p.m. MT
Credit: ARA Staff - American Running Association

Anemia is a condition that occurs when the oxygen-carrying capacity of blood is deficient. When oxygen cannot arrive where it needs to go efficiently and sufficiently, symptoms like weakness, fatigue, trouble concentrating, shortness of breath, dizziness and sexual dysfunction can result. The clearest way to think about anemia and its various causes is by understanding the relationships between hemoglobin, oxygen, red blood cells and iron. Additionally, we’ll look at excessive bleeding, insufficient amounts of vitamin B12 and chronic illness and how these can affect oxygen transport.
Anemia affects both men and women. Since the risk of anemia increases with age, and the symptoms resemble those associated with normal aging, many older adults suffer from the condition without knowing it. There are simple tests that can determine the cause of anemia and then effectively treat it. Although there are sometimes underlying illnesses that cause anemia, it can be useful to think in terms of two separate root causes: a lack of red blood cells, or a lack of iron. (Additional anemia types can be caused by certain genetic defects.)

Iron Deficiency
Hemoglobin is the protein in the blood responsible for picking up and transporting oxygen throughout the body. It resides in red blood cells, and requires iron both to flourish and to bind effectively to oxygen. For this reason, low levels of hemoglobin may signal red blood cell depletion or iron deficiency. (The World Health Organization defines anemia as blood hemoglobin levels below 13 g/dL for men and 12 g/dL for women.) In the same way that oxygen interacts with iron to cause rust, the chemical reaction between iron-rich hemoglobin and oxygen makes blood red. Iron deficiency, then, is a major cause of anemia.
Iron deficiency can be due to a decreased ability to absorb nutrients through food, general malnutrition or a strict vegetarian diet. There’s no getting around it: meat is an important source of iron. A serum ferritin blood test will determine whether your iron levels are low. Your doctor can then prescribe iron supplements. If you are symptomatic of anemia, you should never assume that the reason is iron deficiency and begin taking iron supplements. Always have the blood test performed first. Too much iron can cause toxic levels of iron to accumulate in the liver and pancreas, a dangerous condition known as hemochromatosis. 

Red Blood Cell Depletion
As noted, since hemoglobin lives in red blood cells, another major cause of anemia is a lack of red blood cells. This is really a different problem from a lack of iron, and the varied spectrum of possible causes of it indicates another reason why you shouldn’t simply assume the problem is iron deficiency. What complicates matters is the fact that the two problems are inexorably tied together.
What causes red blood cell depletion? Excessive bleeding such as chronic, low-level GI bleeding can account for it. This may occur with excessive aspirin or NSAID use, or in the case of a stomach ulcer. Similarly, colon polyps, even if benign, can cause this depletion. An endoscopy should be performed if you suspect this to be the source of the bleeding. Regular heavy menstruation in women can also contribute to symptoms of anemia. In all of these cases, red blood cell depletion itself exacerbates iron depletion.
Chronic inflammation from an underlying illness can also cause red blood cell depletion. This type of anemia is not due to iron deficiency. In this scenario, the immune system is signaled to release anti-inflammatory proteins that can interfere with the production of red blood cells. Some causes include a chronic infection, kidney disease and certain cancers. Treating the underlying illness will cure the anemia. A lack of vitamin B12 can also cause a type of anemia, known as Pernicious anemia. This vitamin is necessary for red blood cell production. Typically B12 injections are prescribed and the anemia disappears.
In short, making no assumptions about iron deficiency as itself the total cause of anemia is the key to ensuring long-term wellness. Investigating the possibility of a more serious reason for anemia, for example, colon cancer, is vital.

(Health After 50, 2007, Vol. 19, No. 2, p. 3; Geriatric Times, 2003, Vol. 4, No. 5; Am. J.  Med., 2003, Vol. 115, No. 2, pp. 104-110)

(RUNNING & FITNEWS® June / July / August 2007 • Volume 25, Number 4)
 


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