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Jaundice is a clinical condition also known as hyperbilirubinemia, characterized by yellowish discoloration of the skin, mucous membranes, and sclera of the eyes (also called scleral icterus). This discoloration occurs due to elevated levels of bilirubin.
Jaundice arises when there is an excess of bilirubin resulting from either its excess production or impaired secretion. Under normal circumstances, the serum bilirubin level does not exceed 1 mg/dL. However, the clinical presentation of jaundice becomes evident when the bilirubin level exceeds 3 mg/dL.
Bilirubin consists of two components: conjugated (direct) and unconjugated (indirect). Elevation of either of these components leads to jaundice. In this article, we will discuss the different types and causes of jaundice.
Normally, bilirubin is produced during the daily destruction of red blood cells as part of the regular process of recycling old and damaged red blood cells. The heme part of hemoglobin is converted into bilirubin, which travels through the bloodstream to the liver for metabolism and excretion.
Upon reaching the liver, bilirubin undergoes conjugation with glucuronic acid and is subsequently excreted into the gallbladder. From there, bilirubin travels through the bile ducts into the digestive tract for easy elimination from the body. In the intestines, the majority of bilirubin is excreted in stool, while a small portion undergoes metabolism by intestinal bacteria, transforming into urobilinogen, which is then excreted in urine.
Jaundice occurs when there is dysfunction at any stage of the normal metabolism and/or excretion of bilirubin.
Jaundice has various causes, classified according to the site of the problem. These causes are broadly divided into three main categories: pre-hepatic, hepatic, and post-hepatic:
In this case, jaundice occurs due to the excessive destruction of red blood cells (hemolysis), leading to a rapid increase in bilirubin levels in the blood. This increase exceeds the liver's capacity to metabolize bilirubin properly, resulting in elevated levels of unconjugated bilirubin, a condition known as unconjugated hyperbilirubinemia. This type of jaundice is specifically referred to as hemolytic jaundice.
Diseases that increase blood hemolysis are:
If jaundice occurs during the hepatic phase of bilirubin processing, the cause may be abnormalities in metabolism or excretion. These abnormalities can lead to an increase in both unconjugated and/or conjugated bilirubin levels. This type of jaundice is referred to as hepatocellular jaundice.
Hepatic causes of jaundice are:
In this case, jaundice arises from a disruption in the normal drainage and excretion of conjugated (direct) bilirubin in the form of bile from the liver to the digestive tract. This disruption leads to an elevated level of conjugated bilirubin.
Causes of post-hepatic jaundice:
The diagnosis of jaundice in adults relies on a thorough physical examination of the patient, along with the need to gather more information about the precise cause of jaundice. Additionally, blood tests are essential to assess the level of bilirubin.
1- Liver function tests: measure serum levels of aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), gamma-glutamyl transferase (GGT), serum albumin and bilirubin.
2- Serum bilirubin level: High bilirubin levels are either conjugated and/or unconjugated.
3- Viral serologies: to check if patient has a viral infection for example hepatitis A, B, C.
4- Autoimmune antibodies.
5- Urinalysis.
6- Complete blood count (CBC).
7- Abdominal ultrasound, computerized tomography (CT) scan and magnetic resonance imaging (MRI).
8- Magnetic resonance cholangiopancreatography (MRCP): this is a MRI of bile and pancreatic ducts which provides better imaging of ducts than conventional MRI.
9- Endoscopic retrograde cholangiopancreatography (ERCP): In an ERCP, a radiopaque contrast agent is injected into the pancreatic and bile ducts using a flexible viewing tube (endoscope) that is placed via the mouth and into the small intestine.
10- Liver biopsy.
The treatment of jaundice primarily depends on addressing the underlying cause, and once a diagnosis is established, appropriate interventions should be initiated. Treatment plans may vary, with some patients requiring hospitalization while others can be managed at home.
In conclusion there are plenty of causes that result in jaundice in adults, moreover, depending on the cause, the management plan is decided accordingly.
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