A yellow discoloration of the skin due to the deposition of BILE pigment in its deeper layers. It is the main sign of various disorders of the liver and biliary system.
There are three types of jaundice, all the result of disturbance in the way HAEMOGLOBIN, released by the breakdown of ageing red blood cells, is not properly processed in the liver. Normally the breakdown product of this haemoglobin – bilirubin – is dissolvable in water and is excreted via the bile ducts into the small intestine, where it colours the stools dark brown.
In this type, the amount of bilirubin produced is too much for the liver to deal with, usually the result of a high level of HAEMOGLOBIN from excessive breakdown of blood cells. This haemolytic anaemia has several causes (see ANAEMIA). It can be a particularly serious problem in some newborn babies whose blood group is not compatible with that of their mother. (See Haemolytic Disease of the Newborn.)
In this disorder, bilirubin builds up in the blood because liver cells have been damaged or have died – usually as a result of viral HEPATITIS, or of liver failure. A form of this in the newborn is common, simply due to immaturity of liver cells and is generally harmless.
Also called cholestatic jaundice, this type is characterised by the inability of the liver to discharge bile because the bile ducts are blocked as a result of gall-stones (see under GALL-BLADDER, DISEASES OF) or a tumour. A congenital variety involves the ducts being absent (BILIARY ATRESIA) or destroyed in the liver as a result of CIRRHOSIS (see also GILBERT'S SYNDROME).
Yellowness, appearing first in the whites of the eyes and later over the whole skin, is the symptom that attracts notice. Indigestion, nausea, poor appetite and general malaise are other symptoms. The skin may itch, and the faeces are pale because of the absence of bile.
After thorough investigation to determine the cause, this is then treated appropriately. F (See also LIVER, DISEASES OF.) Newborns are treated with phototherapy, light applied close to the skin which results in a chemical reaction that changes the bilirubin into other harmless pigments. Babies with haemolytic disease of the newborn may need an exchange transfusion in which their blood is removed a syringe-full at a time and replaced by compatible donor blood.