Anemia is a decrease in hemoglobin levels from an individual's baseline; however, sex-specific and race-specific reference ranges to make a diagnosis are often used when baseline hemoglobin is not known. The World Health Organization (WHO) criteria for anemia in men is less than 13 g/dL, whereas it is less than 12 g/dL for women. There are revised criteria for anemia in men and women with complications of chemotherapy as well as age and race. Even "special populations" such as athletes, smokers, older adults, or those living at high altitudes have suggested different ranges.
The critical issue in evaluating any form of anemia is to recognize treatable causes early. This is crucial because hemoglobin, an iron-rich protein, is what helps red blood cells (RBC), carry oxygen from the lungs to the rest of the body. The biconcave shape of RBCs themselves allows for it to provide optimal respiratory exchange. If the body is unable to provide oxygen to the body, one may experience symptoms of weakness, lethargy, dizziness, headaches, shortness of breath, or arrhythmias.
Anemia is often subcategorized into microcytic, normocytic, and macrocytic based on mean corpuscular volume (MCV). As there are numerous types of anemia, this laboratory parameter allows clinicians to formulate a practical diagnostic approach.
Hemolytic anemia is classified as normocytic anemia with an MCV of 80 to 100 fL. It is a form of low hemoglobin due to the destruction of red blood cells, increased hemoglobin catabolism, decreased levels of hemoglobin, and an increase in efforts of bone marrow to regenerate products.
Hemolytic Anemias can be further subdivided into intrinsic and extrinsic causes.
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