Blood tests are a routine diagnostic tool that offer insights into an individual’s health. Understanding these tests helps individuals engage with their health. They provide a snapshot of bodily functions, identifying areas needing attention. Learning about specific blood panel components clarifies what results signify.
What is Total Bilirubin
Total bilirubin (TBIL) is a yellowish pigment in bile, produced by the liver. It originates from the breakdown of heme, a component of hemoglobin in red blood cells. When red blood cells complete their lifespan, they are processed in the spleen, bone marrow, and liver. During this process, heme is converted into unconjugated, or indirect, bilirubin.
This unconjugated bilirubin travels through the bloodstream, bound to albumin, to the liver. Within the liver, enzymes transform it into conjugated, or direct, bilirubin. This conjugated form is water-soluble and can be excreted from the body. It is then released into the bile ducts and passes into the small intestine, where it is eliminated through stool, contributing to its brown color.
Why the TBIL Test is Performed
A healthcare provider may order a TBIL blood test to assess liver function and identify conditions affecting red blood cell breakdown. It is often used when an individual shows signs of jaundice (yellowing of the skin and eyes), a common indicator of elevated bilirubin. This symptom is particularly relevant in newborns, where monitoring bilirubin is standard practice to address neonatal jaundice.
The TBIL test is also part of a comprehensive liver panel, evaluating liver health alongside other enzymes and proteins. It helps diagnose and monitor various liver diseases, such as hepatitis or cirrhosis, by indicating how effectively the liver processes and eliminates bilirubin. It also investigates conditions causing accelerated red blood cell destruction, like hemolytic anemia, where rapid breakdown leads to increased bilirubin.
Interpreting Your TBIL Results
Interpreting total bilirubin results requires understanding typical ranges and what deviations suggest. For adults, a normal total bilirubin level falls between 0.3 and 1.2 milligrams per deciliter (mg/dL). Newborns often have higher bilirubin levels shortly after birth, peaking within the first few days, with ranges varying by age and other factors. Levels above the normal adult range indicate hyperbilirubinemia (excess bilirubin in the bloodstream).
Elevated total bilirubin can point to issues with the liver’s ability to process bilirubin, blockages in the bile ducts, or an increased rate of red blood cell destruction. Lower total bilirubin levels are less common and generally do not indicate a medical concern. These ranges are general guidelines; a healthcare provider considers them within an individual’s overall health, symptoms, and other findings.
Common Causes of Abnormal TBIL Levels
Elevated total bilirubin levels can stem from various medical conditions affecting the liver, bile ducts, or red blood cell breakdown. Liver diseases, such as acute hepatitis or chronic cirrhosis, impair the liver’s ability to process unconjugated bilirubin or excrete conjugated bilirubin, leading to its accumulation. Conditions like Gilbert’s syndrome, a common genetic disorder, cause mild, fluctuating increases in unconjugated bilirubin due to reduced liver conjugation capacity.
Obstructions in the bile ducts, such as those caused by gallstones or tumors, prevent conjugated bilirubin from being excreted into the intestines. This backup forces conjugated bilirubin back into the bloodstream, elevating levels. Conditions causing increased red blood cell destruction (hemolysis) also contribute to high bilirubin. Hemolytic anemias, for instance, lead to rapid red blood cell breakdown, overwhelming the liver’s capacity to process unconjugated bilirubin.
Next Steps After an Abnormal Result
An abnormal total bilirubin result prompts further investigation by a healthcare provider. The initial step involves discussing the individual’s medical history and symptoms. To pinpoint the cause, additional blood tests are often ordered. These may include measurements of direct (conjugated) and indirect (unconjugated) bilirubin, as well as other liver enzymes like alkaline phosphatase (ALP), alanine aminotransferase (ALT), and aspartate aminotransferase (AST).
Imaging studies (ultrasound, CT scan, or MRI of the abdomen) might be recommended to visualize the liver and bile ducts for abnormalities or obstructions. The subsequent course of action, including treatment, depends on the underlying condition identified as the cause. A healthcare professional will provide tailored guidance and explain the diagnostic process and treatment options.