A reduction in the normal amount of red blood cells in the body causes anemia. Red blood cells, which are produced in the bone marrow, contain hemoglobin molecules that carry oxygen to all parts of the body. If red blood cells decrease, hemoglobin and oxygen availability decrease accordingly, resulting in anemia. Anemia can be classified as mild, moderate or severe.
Normal hemoglobin levels range from 11.5 mg/dL to 17.5 mg/dL depending on gender. The World Health Organization (WHO) defines anemia as a hemoglobin level less than 13.0 g/dL in adult men and less than 12 g/dL in adult women. Data presented at the American Society of Clinical Oncology Annual Meeting (ASCO) in 2005 defined mild anemia as hemoglobin concentrations in the range of 12 g/dL to 14 g/dL for men or 10 g/dL to 12 g/dL for women.
Low levels of iron cause iron deficiency anemia, the most common type of anemia. It affects about 1 to 2 percent of adults in the United States. Iron is needed to make hemoglobin. According to the National Institute of Health, about 20 percent of women, 50 percent of pregnant women and 3 percent of men do not have enough iron in their body.
Low levels of vitamin B12 cause vitamin deficiency anemia. In addition to iron, the body needs vitamin B12 to produce adequate numbers of red blood cells. Low levels of folate cause folate deficiency anemia. In addition to iron and vitamin B12, folate is also required for red blood cell production. Chronic diseases such as cancer, kidney disease, HIV/AIDS, autoimmune disease, hepatitis C and other chronic inflammatory diseases cause anemia. These diseases interfere with the body's ability to generate red blood cells.
People at Risk
Individuals at risk for developing anemia include women in childbearing years due to blood loss during menstruation, pregnant women, infants and children who do not receive an adequate amount of iron in their diet and elderly individuals. People with chronic diseases such as cancer, kidney disease, HIV/AIDS, autoimmune disease, hepatitis C and other chronic inflammatory diseases are also at risk for anemia.
Currently there is not a lot of research on mild anemia. Most experts on anemia believe that the majority of people with mild anemia do not have symptoms. If they do have symptoms they are mild. Because of this, anemia can go undetected and untreated.
According to a report by Robert H. Shmerling, M.D. at the Beth Israel Deaconess Medical Center, Boston, moderate to severe anemia causes fatigue, headaches, palpitations, shortness of breath and even chest pain leading to heart attack (though usually in persons with underlying heart disease). When anemia becomes severe, symptoms may develop at rest and include difficulty breathing, confusion or lethargy. Dr. Shmerling's report also states that mild anemia rarely causes fatigue and symptoms usually persist even when mild anemia has been corrected.
On the other hand, cancer research shows that people with mild anemia experience more symptoms than is currently thought. A study presented at ASCO, 2005 on 3415 anemia patients concluded that symptoms and quality of life gets worse as soon as hemoglobin levels drop and anemia gets worse. Research is ongoing on the topic.
A common misconception of anemia treatment is that iron is the only way to treat it. While this may be true a lot of the time it is not true all of the time. Treatment for anemia depends on the type, cause, and severity of the condition. For example if iron deficiency caused anemia your doctor will try to raise your iron levels by increasing your dietary iron and prescribing iron supplements.
If kidney disease caused anemia, your doctor will choose another way to treat your anemia. Kidney disease prevents your body's ability to generate red blood cells. The kidneys produce a hormone called erythropoietin (EPO). EPO controls red blood cell production. Damaged kidneys means reduced amount of EPO and hence red blood cells decrease accordingly. Your physician will prescribe EPO for you to help you produce red blood cells if you need it.
What Patients Can Do
According to a report at the Mayo Clinic, diagnosing anemia early or mild anemia can help identify early signs of serious illnesses. If you experience any symptoms of anemia, tell your doctor. If you have any diseases that cause anemia, make sure your hemoglobin levels are checked on a regular basis. For example, if you have kidney disease, the National Kidney Foundation recommends you check your hemoglobin level at least once a year.
- National Institutes of Health: General information on Anemia
- Facts and Myths About Anemia Robert H. Shmerling, M.D: Normal hemoglobin levels range from 11.5 mg/dL to 17.5 mg/dL
- The Prognostic Value of Anemia: Definition of anemia WHO
- Update on the Use of Hematopoietic Growth Factors and Anemia, ASCO 2005: Mild Anemia Definition
- National Institutes of Health: 20% of women, 50% of pregnant women, and 3% of men do not have enough iron