Jaundice (Icterus).
DEFINITION.—The term jaundice has its origin in the French word jaune, yellow. Icterus, which has come to be a more technical word, is of uncertain Greek origin, and is much employed by French writers as ictère. The common German name is Gelbsucht, a highly expressive designation. Jaundice signifies a yellow discoloration of the skin caused by the presence of bile. It is a symptom rather than a disease. As a symptom it will receive much consideration in the pages to follow, but there is also a functional disorder—a jaundice due to a disturbance in the biliary functions, without evidences of structural change—which must be discussed here. This preliminary statement of our present knowledge of jaundice will facilitate the comprehension of it as a symptom, and will render unnecessary explanations that will be merely a repetition of previous ones.
CAUSES.—The theories of the causation of jaundice may be reduced to three: 1, that it is due to a disorganization of the blood in which the coloring matter is set free, and hence is known as hæmatogenous; 2, that the materials of the bile, which it is the office of the liver to remove from the blood, are not so disposed of; 3, that the bile, after being formed by the liver, is absorbed into the blood because of an obstacle to its escape, and hence this is called hepatogenous jaundice.
The modern view of hæmatogenous jaundice had its origin in the supposed discovery of the identity of hæmatoidin with bilirubin. If the pigment of the blood has the same composition as the pigment of the bile, hæmatogenous jaundice will be produced whenever hæmatoidin is set free in the blood. Virchow13 was the first investigator to show the close resemblance between these two pigments. Since his observation was made an identity of hæmatoidin and bilirubin has been maintained by Zenker, Valentiner, Kühne, and others, and as strenuously denied by Städeler, Preyer, Young, and others. At the present time it appears to be established that although the blood- and bile-pigments are closely related, they are not identical.14 Nevertheless, a hæmatogenous jaundice is still admitted to exist by Leyden,15 Immermann,16 Gubler,17 Ponfick,18 and some others. The existence or non-existence of this form of jaundice is, however, of little importance in this connection, since, if it ever occur, the malady of which it is a symptom is not an affection of the liver, but of the blood, as phosphorus-poisoning, pyæmia, etc.
13 Archiv für path. Anat., etc., Band i. p. 370, 1847.
14 Legg, J. Wickham, On the Bile, Jaundice, and Bilious Diseases, p. 243.
15 Beiträge zur Pathologie des Icterus, Berlin, 1866, p. 6.
16 Deutsch. Archiv für klin. Med., Band xii. p. 502.
17 Union médicale, 1857, p. 503.
18 Ziemssen's Cyclopædia, vol. ix. p. 24.