Canadian Society for Medical Laboratory Science (CSMLS) Practice Exam

What is indicated by the presence of bilirubin in urine?

1. Liver disease

2. Kidney disease

3. Diabetes mellitus

4. Dehydration

The correct answer is: Liver disease

The presence of bilirubin in urine typically indicates liver disease. Bilirubin is a byproduct of the breakdown of red blood cells and is processed by the liver. Under normal circumstances, bilirubin is primarily excreted into the bile and enters the digestive system. However, when the liver is damaged or diseased—due to conditions such as hepatitis, cirrhosis, or obstruction of bile ducts—bilirubin can leak into the bloodstream and subsequently be filtered out by the kidneys into the urine. When bilirubin is detected in urine, it often reflects an increase in conjugated bilirubin levels in the bloodstream, as the kidneys are effectively excreting what the liver cannot process adequately. This is a significant indicator of underlying liver dysfunction and highlights the liver's essential role in bilirubin metabolism. In contrast, conditions such as kidney disease, diabetes mellitus, or dehydration do not specifically correlate with the presence of bilirubin in urine and reflect different physiological processes or abnormalities. For instance, while kidney disease might show other abnormal substances or proteins in urine, the presence of bilirubin is not a primary marker for renal dysfunction.