Jaundice, a yellow colour of the skin and conjunctiva of the eye, arising from the presence of the colouring matter of the bile in the blood and tissues, is a symptom of various disordered conditions of the system rather than a special disease. With this colouring of the skin and eyes the following symptoms are associated: the faeces are of a grayish or dirty-white tint, in consequence of the absence of bile, and the urine is of the colour of saffron, or is even as dark as porter, in consequence of the presence of the colouring matter of the bile. There is sometimes, but not in the majority of cases, an extreme itching of the skin. It is a popular belief, as old as the time of Lucretius, that to a jaundiced eye everything appears yellow. This, however, is a very rare symptom.
The causes of jaundice naturally fall into two classes, those where there is mechanical obstruction of the bile-duct, and those where there is no obstruction. Mechanical obstruction may be produced by gall-stones (see CALCULUS) or thickened bile within the duct; by inflammatory swelling of its lining membrane or that of the duodenum, into which it discharges (catarrhal jaundice); by the pressure upon it of tumours of neighbouring parts, of the pregnant uterus, or of accumulations of faeces in the bowels. Jaundice may result without obstruction of the ducts from congestion or cirrhosis of the liver, from severe mental emotions (anger, fright, &c.), and especially from the action of various poisons—e.g. phosphorus, arsenic, mercury, snake-poison—and of various acute diseases —e.g. typhus fever, pyæmia, and above all yellow fever. In cases of obstructive jaundice, all authorities are agreed in referring the yellow staining of the skin and other tissues to absorption by the lymphatics and veins of the bile-pigment, which is secreted by the liver but not discharged into the intestine. The explanation of non-obstructive jaundice is, however, not so clear, and raises complicated physiological questions. According to one theory, the bile-pigments are formed in the blood and merely excreted by the liver; and on this view non-obstructive jaundice is caused by their defective elimination owing to diminished activity of the liver-cells. Others hold that the bile-pigments are not formed except by the action of the liver-cells; that in non-obstructive jaundice also secretion and re-absorption always take place; and that the bile-pigments continue in the circulation owing to some defect not fully understood in the processes occurring in the blood. The question must be regarded as an open one; but the latter theory seems at present most in favour.
Both prognosis and treatment of jaundice depend entirely upon the recognition of the cause to which it is due. In cases of gall-stones, catarrhal jaundice, pressure of the pregnant uterus or of fecal accumulations, and of congestion of the liver, the case usually terminates favourably; in cases of tumour and of cirrhosis of the liver the outlook is always grave; in poisoning and in acute diseases jaundice is often a very serious symptom; where it results from mental emotion it sometimes disappears quickly, but is often followed by severe nervous symptoms and death. See LIVER (DISEASES OF).