Hypochromic anemia is a generic term for any type of anemia in which the red blood cells are paler than normal. (Hypo- refers to less, and chromic means colour.) A normal red blood cell has a biconcave disk shape and will have an area of pallor in its center when viewed microscopically. In hypochromic cells, this area of central pallor is increased. This decrease in redness is due to a disproportionate reduction of red cell hemoglobin (the pigment that imparts the red color) in proportion to the volume of the cell. Clinically the color can be evaluated by the mean corpuscular hemoglobin (MCH) or mean corpuscular hemoglobin concentration (MCHC). The MCHC is considered the better parameter of the two as it adjusts for effect the size of the cell has on its amount of hemoglobin. Hypochromia is clinically defined as below the normal MCH reference range of 27–33 picograms/cell in adults or below the normal MCHC reference range of 33–36 g/dL in adults. Red blood cells will also be small (microcytic), leading to substantial overlap with the category of microcytic anemia. The most common causes of this kind of anemia are iron deficiency and thalassemia. Hypochromic anemia was historically known as chlorosis or green sickness for the distinct skin tinge sometimes present in patients, in addition to more general symptoms such as a lack of energy, shortness of breath, dyspepsia, headaches, a capricious or scanty appetite and amenorrhea. Historical understanding In 1554, German physician Johannes Lange described a condition, which he called "the disease of virgins" because, he said, it was "peculiar to virgins". The symptoms were wide-ranging, including an appearance which is "pale, as if bloodless", an aversion to food (especially meat), difficulty in breathing, palpitations and swollen ankles. He prescribed that those affected should "live with men and copulate. If they conceive, they will recover." The symptom picture overlaps to some extent with an earlier condition described in English medical texts, "the green sickness", which was a form of jaundice. However, Lange shifted the cause from digestive errors to the patient remaining a virgin, despite being of the age for marriage. The name "chlorosis" was coined in 1615 by Montpellier professor of medicine Jean Varandal from the ancient Greek word "chloros" meaning "greenish-yellow", "pale green", "pale", "pallid" or "fresh". Both Lange and Varandal claimed Hippocrates as a reference, but their lists of symptoms do not match that in