Jaundice and Lab Testing

Jaundice, also called icterus, is a condition where the skin, the whites of the eyes, and even body fluids turn significantly yellow following an increase in the levels of bilirubin in the blood. Bilirubin is a yellowish substance that forms from the normal breakdown of red blood cells (or RBCs). Red blood cells normally live for about 120 days before being broken down by the body, a process that results in the formation of bilirubin. Bilirubin is then transported to the liver where it is metabolized and excreted in bile. Bile is a yellow-green-to-brown fluid that is released into the duodenum to help in the digestion of lipids and the elimination of waste substances like bilirubin and excess cholesterol. Changes to the normal metabolism process or overproduction of bilirubin may lead to jaundice. 

Jaundice is not an illness, per se. Rather, it is a medical condition that may indicate an underlying liver, pancreas, or gallbladder problem. Jaundice can be caused by several factors, including infections, cancer, use of certain drugs, gallstones, blood disorders, inherited conditions, congenital disabilities, among other medical conditions.

Generally, the causes of jaundice may be categorized into these three groups: 

  • Conditions that arise from the inability of the liver to metabolize and eliminate bilirubin 
  • Conditions that cause shortened life for red blood cells, which in turn leads to increased levels of bilirubin 
  • Conditions that inhibit the elimination of bilirubin from the body 

Common Causes of Jaundice 

Acute hepatitis: inflammation of the liver due to various reasons, including hepatitis A, B, C, D, and E, alcohol abuse, viral infections, toxins, and some medicines such as acetaminophen. 

Blockage of the bile duct, which may be caused by: 

  • Damage and Scarring 
  • Biliary atresia, a congenital condition linked to the abnormal development of the bile duct, which results in the backup and pooling of bile and an increase in the level of bilirubin in the blood. 
  • Gallstones 
  • Pancreatic cancer may sometimes lead to the blockage of the bile duct. 

Conditions that result in a significant increase in the rate of red blood cell destruction cause an increase in bilirubin production. Such conditions include hemolytic anemia, due to an abnormal variant of hemoglobin, autoimmune disorders, malaria, or hemolytic disease of the newborn (or HDN). 

Gilbert syndrome: an inherited condition that is associated with reduced bilirubin metabolism due to decreased enzyme activity. Individuals with Gilbert syndrome may have passing jaundice during times of sickness or stress and times of increased levels of unconjugated bilirubin. 

Cirrhosis: jaundice can occur in the late stages of cirrhosis. 

Laboratory Tests 

Some of the tests used to assess liver function and detect liver damage include: 

Liver panel, which often comprises: 

ALT (or Alanine aminotransferase) 

AST (or Aspartate aminotransferase) 

ALP (or Alkaline phosphatase) 

Bilirubin, Total (conjugated and unconjugated), Direct (conjugated) and Indirect (unconjugated) 

GGT (or Gamma-glutamyl transferase) 


Prothrombin time (or PT): the liver produces essential proteins for blood clotting/coagulation. The PT measures the clotting function, which may indicate liver damage if abnormal. 

Urine bilirubin, which often falls under a urinalysis 

Some tests are important for the detection of infections that affect the liver, including: 

Hepatitis A 

Hepatitis B 

Hepatitis C 

Hepatitis E 

Epstein-Barr virus (or EBV) 

Cytomegalovirus (or CMV) 

Tests that come in handy in detecting reduced red blood cell survival include: 

Complete blood count (or CBC) 

Blood smear: to observe red blood cells under a microscope 

Reticulocyte count (whenever CBC is abnormal)