From the Guidelines
No, a CBC (Complete Blood Count) with differential does not include a bilirubin level. A CBC with differential measures various components of blood including red blood cells, white blood cells (with a breakdown of different white cell types), platelets, hemoglobin, and hematocrit. Bilirubin is a separate test that measures the amount of this yellow pigment in the blood, which is a breakdown product of hemoglobin. Bilirubin testing is typically included in liver function tests or comprehensive metabolic panels, not in a CBC. If you need to assess bilirubin levels to evaluate for conditions like jaundice, liver disease, or hemolytic anemia, you would need to specifically request a bilirubin test or a liver function panel in addition to the CBC. The distinction is important because these tests evaluate different aspects of health - CBC primarily assesses blood cell production and function, while bilirubin testing evaluates liver function and red blood cell breakdown.
Key Components of a CBC
- Red blood cells
- White blood cells (with a breakdown of different white cell types)
- Platelets
- Hemoglobin
- Hematocrit
Bilirubin Testing
Bilirubin testing is used to evaluate liver function and red blood cell breakdown, and is typically included in liver function tests or comprehensive metabolic panels. According to the most recent study 1, hyperbilirubinemia is defined by a serum bilirubin >2.5 to 3 mg/dL, and can be caused by prehepatic, intrahepatic, or posthepatic factors.
Clinical Implications
In clinical practice, it is essential to distinguish between CBC and bilirubin testing, as they evaluate different aspects of health. A CBC is used to assess blood cell production and function, while bilirubin testing is used to evaluate liver function and red blood cell breakdown. As noted in the study 1, an initial assessment of hepatic function involves liver function testing, including measurement of serum levels of bilirubin, aspartate aminotransferase, alanine transaminase, alkaline phosphatase, and other tests.
Laboratory Tests
Laboratory tests, such as full blood count with differential, comprehensive metabolic panel, liver enzymes, and lipase, are essential in evaluating patients with inflammatory bowel disease, as noted in the study 1. However, bilirubin testing is not included in a CBC with differential.
In summary, a CBC with differential does not include a bilirubin level, and bilirubin testing should be specifically requested if needed to evaluate liver function and red blood cell breakdown.
From the Research
Complete Blood Count (CBC) with Differential
- A Complete Blood Count (CBC) with differential is a common laboratory test used to evaluate various blood components, including red and white blood cell counts, hemoglobin, and platelet count 2.
- The test is often used to diagnose and monitor a range of conditions, including anemia, infection, and blood disorders.
Bilirubin Level
- Bilirubin level is typically measured as part of liver function testing, rather than as part of a CBC with differential 3, 4, 5.
- Elevated bilirubin levels can indicate jaundice, liver disease, or hemolysis, and are often evaluated in conjunction with other laboratory tests, such as liver enzymes and blood cell counts 3, 4, 5, 6.
Relationship between CBC with Differential and Bilirubin Level
- While a CBC with differential can provide information about blood cell counts and morphology, it does not typically include a direct measurement of bilirubin level 2.
- However, a CBC with differential may be used in conjunction with other laboratory tests, including bilirubin measurement, to evaluate patients with suspected liver disease or hemolysis 3, 4, 5, 6.