Icterus, commonly known as jaundice, refers to the yellow discoloration of body tissues, most noticeably the skin and the whites of the eyes. When detected in a blood test, icterus indicates an underlying medical condition. Its presence and severity highlight an imbalance in the body’s metabolic processes that requires professional medical attention.
What Icterus Means
Icterus is the medical term for jaundice, a condition characterized by a yellowish tint to the skin, the whites of the eyes (sclera), and mucous membranes. This yellowing occurs due to the excessive accumulation of bilirubin in the body’s tissues. Bilirubin is a yellow pigment that forms as a natural byproduct when old red blood cells break down. It originates from the heme component of hemoglobin, the protein in red blood cells responsible for carrying oxygen. Under normal circumstances, the liver processes this bilirubin, making it water-soluble for excretion from the body, primarily through bile and then in stool.
How Icterus is Detected in Blood
Icterus is detected and monitored through a bilirubin blood test. This test measures the levels of bilirubin circulating in the bloodstream. The bilirubin test assesses three components: total bilirubin, unconjugated (indirect) bilirubin, and conjugated (direct) bilirubin.
Unconjugated bilirubin is the form produced after red blood cell breakdown; it is not water-soluble and travels through the blood bound to a protein called albumin. The liver then processes this, converting it into water-soluble conjugated bilirubin for excretion in bile. Elevated levels of either type indicate a disruption in the body’s ability to process or eliminate this pigment.
Why Bilirubin Levels Rise
Elevated bilirubin levels, causing icterus, stem from various medical reasons categorized by where the problem originates in the bilirubin processing pathway.
Pre-hepatic Causes
This category involves problems before bilirubin reaches the liver, meaning the issue occurs before bilirubin reaches the liver. This often involves an increased breakdown of red blood cells, known as hemolysis, which overwhelms the liver’s capacity to process the large amount of unconjugated bilirubin produced. Hemolytic anemia, where red blood cells are destroyed prematurely, is an example.
Hepatic Causes
Here, the problem lies within the liver itself. Liver damage or dysfunction impairs its ability to properly process bilirubin. Causes include viral hepatitis, alcoholic liver disease, or cirrhosis. Genetic conditions like Gilbert’s syndrome also affect the liver’s enzyme activity in conjugating bilirubin.
Post-hepatic Causes
These issues occur after the liver has processed bilirubin, typically involving an obstruction of the bile ducts. Blockages prevent conjugated bilirubin from being excreted from the body. Common causes include gallstones, pancreatic tumors, or bile duct strictures, leading to conjugated bilirubin accumulation in the bloodstream.
What High Bilirubin Indicates
High bilirubin levels, as revealed by a blood test, indicate an underlying health problem that requires medical attention. Beyond the visible yellowing, individuals with elevated bilirubin might experience other symptoms such as unusually dark urine, pale or clay-colored stools, and itchy skin. These accompanying symptoms can provide further clues about the cause of the bilirubin elevation. A high bilirubin level necessitates additional diagnostic tests to pinpoint the exact condition. These may include imaging studies like ultrasound or CT scans, as well as other liver function tests. Determining the precise cause is crucial, as the appropriate medical treatment depends on addressing the specific underlying condition.