Anæmia (Gr., 'bloodlessness') is a comprehensive term employed to denote those conditions in which there is a diminished quantity of blood, or a smaller number of its corpuscles, than in health. In some forms of disease in which anæmia is a characteristic feature, there is an absolute reduction in the amount of blood in the body; in others there is merely a reduction in the number of the red corpuscles; and in others again, the reduced number of the red is accompanied by an increase in the number of the white corpuscles. The symptoms present in anæmia are weakness and languor; tendency to headaches, especially at the top of the head, and to neuralgias in various situations; singing in the ears, and troubles connected with the sight; palpitation and faintness; breathlessness on exertion; sleeplessness and irritability; poor appetite and weak digestion; with habitual constipation, and, in women, disorders of the catamenial functions. The patient presents a blanched appearance, the face being pale, and the lips, gums, and mucous membrane of the eyelids bloodless; the skin has a dull aspect, and the hair is scurvy. In many of the cases there may be no emaciation—rather, on the other hand, a tendency to plumpness; but the muscles are flabby, and there is frequently also dropsy about the ankles. There are always abnormal sounds or murmurs in the vessels, especially the veins, and frequently also in the heart, which is enlarged by dilatation. In some cases even of ordinary anæmia there is enlargement of the spleen, and, more rarely, of the liver. Occasionally there is albumen in the urine. The blood in health should contain 5,000,000 red corpuscles per cubic millimetre, but on estimating it in anæmia there may be a great reduction in the number. The white corpuscles are estimated to be present in health in the ratio of one to three hundred or five hundred, but this ratio may be altered by a relative or absolute increase of the white cells.
The causes of anæmia, following Osler, may be divided into two groups, according as they act upon the blood directly, or upon the blood-forming structures. Under the first division must be placed losses of blood by hemorrhage, as, for instance, from the stomach, lungs, or uterus, in which there may be a great diminution in the quantity of the blood, with a corresponding reduction of the red blood-corpuscles, and a lesser reduction of the white cells; losses produced by a drain on the albuminous elements of the blood by pus-formation, albuminuria, or lactation; diminished blood-formation by want of food, or conditions preventing its reception or assimilation by the organism, in which the blood-plasma loses more than the blood-corpuscles—as examples of which, may be mentioned inanition, diseases of the gut, and simple chlorosis; and, lastly, the effects of certain poisons which interfere with blood-formation, such as metallic substances like mercury or lead, and organic agents like malaria. In all these forms of anæmia, the treatment consists in the removal, if possible, of the cause, the enjoyment of sunlight and fresh air, with good food and the administration of iron. In the second group, there fall to be considered causes which act by disturbing the functions of the blood-making organs—to wit, the spleen, the bone marrow, and the general lymphatic tissues of the body. Curiously enough, when there is enlargement of any of these structures, there is a disturbance of its functions. Enlargement of the spleen is always followed by the anæmia splenica of Griesinger, a common sequel to malaria; changes in the marrow of the bones is often associated with the form of anæmia known as idiopathic, or progressive pernicious anæmia; and affections of the general lymph-glands throughout the body are associated with anæmia, in the disease known as adenia or Hodgkin's disease. In all these affections there is no increase in the number of the white cells; but there is another analogous disease characterised by changes in the spleen, marrow, and glands, associated with an increase in the white cells, and reduction of the red corpuscles. This is the affection known as leukæmia. In all these diseases arsenic appears to be the only remedy of any utility, but most of them are in our present state of knowledge incurable.