医学英語のリーディングとリスニング

The term anemia literally means "without blood" based on "an" which means "without" and "emia" which means "blood." Anemia is, however, a bit of a misnomer, and this condition is actually characterized not by the total absence of blood, but rather by an abnormally low red blood cell count or red blood cells, which do not carry enough hemoglobin. Hemoglobin is an iron-rich protein that gives blood its red color and carries oxygen from the lungs to the rest of the body.

Anemia has three main causes, specifically, blood loss, lower than normal levels of red blood cells, also known as RBCs, or higher than normal rates of RBC destruction. These causes can act alone or in concert. The major risk factors for anemia include: a poor or inadequate diet that is low in iron, vitamins or minerals; blood loss from surgery or injury; chronic or serious illnesses such as cancer, inflammatory bowel disease or diabetes; chronic infections and a family history of inherited anemia such as sickle cell anemia.

The most common symptom of anemia is fatigue. Other signs and symptoms include shortness of breath, dizziness, headache, coldness in the extremities, pale skin and chest pain. These signs and symptoms are primarily attributable to the need for the heart to work harder to pump oxygen throughout the body. The severity of anemia ranges from mild to life-threatening.

Anemia can be diagnosed using different tests or procedures. The first test usually is a complete blood count also known as a CBC. The CBC reveals a number of things about a person's blood including his or her hemoglobin level and hematocrit level. Lower than normal values of either hemoglobin or hematocrit point to anemia. Additional tests that help to pinpoint the exact type of anemia include hemoglobin electrophoresis and reticulocyte count. Hemoglobin electrophoresis is used to evaluate the different types of hemoglobin in the blood and can be used to diagnose those types of anemia caused by abnormal hemoglobin in RBCs. The reticulocyte count test, as the name implies, indicates the number of reticulocytes. Reticulocytes are young red blood cells and they circulate in the bloodstream for about 2 days before developing into mature red blood cells. These cells account for approximately 1% to 2% of all RBCs. An abnormal number of reticulocytes can point to abnormal bone marrow function, blood loss or destruction of RBCs earlier than their normal life span of 120 days.

Treatments for anemia are as diverse as the condition itself and range from improving the patient's diet, nutritional supplements, drug therapy, blood transfusions to bone marrow transplants. The prognosis also varies depending upon multiple factors including the type of anemia and patient compliance with treatment.