Laboratory Tests in diagnosing CCA
While there are no definitive laboratory tests specifically for cholangiocarcinoma, there are several tests that your physician may order to rule out other diseases and narrow the diagnosis. There are also tests know as Tumor Markers that your physician may order before, during and after initiation of chemotherapy to determine your progress during treatment.
Liver Function Tests This includes multiple serum (blood) tests to determine liver function and the extent, if any, of liver function impairment by measuring enzymes that liver cells release in response to damage or disease. These are broad spectrum tests which help physicians to narrow the Differential Diagnosis*. (*Differential Diagnosis refers to the process of weighing the probability of one disease versus that of other diseases possibly accounting for a patient’s illness. The differential diagnosis of specific elevated liver enzymes may include cirrhosis, chronic hepatitis C, viral hepatitis, cholestasis and pancreatitis).
- Albumin and total protein. Levels of albumin — a protein made by the liver — and total protein show how well your liver is making proteins that your body needs to fight infections and perform other functions. Lower than normal levels may indicate liver damage or disease.
- Alanine transaminase (ALT). An enzyme found mainly in liver cells, ALT helps your body metabolize protein. Normally, ALT levels in the blood are low. When the liver is damaged, ALT is released in the bloodstream and levels increase.
- Alkaline phosphatase (ALP). ALP is an enzyme found in high concentrations in the liver and bile ducts, as well as some other tissues. Higher than normal levels of ALP may indicate liver damage or disease.
- Alpha-fetoprotein (AFP). AFP is the fetal counterpart of Albumin; levels subside after birth to adult levels within 12 months. Although levels of AFP in adults are usually very low, they are detectable. It is most useful as a tumor marker to detect germ cell tumors and is often elevated in cases of hepatocellular carcinoma but can be elevated in cases of cholangiocarcinoma. It can be elevated in non-cancerous conditions such as viral hepatitis and cirrhosis.
- Aspartate transaminase (AST). The enzyme AST plays a role in the metabolism of alanine, an amino acid. AST is found in high concentrations in liver cells. An increase in AST levels may indicate liver damage or disease.
- Bilirubin. Bilirubin results from the breakdown of red blood cells. Normally, bilirubin passes through the liver and is excreted in your stool. Elevated levels of bilirubin (jaundice) may indicate liver damage or disease.
- Gamma-glutamyltransferase (GGT). This test measures the amount of the enzyme GGT in the blood. Higher than normal levels may indicate liver or bile duct damage.
- L-lactate dehydrogenase (LDH). LDH is an enzyme found in many body tissues, including the liver. Elevated levels of LDH may indicate liver damage.
- Prothrombin time (PT). This test measures the clotting time of plasma. Increased PT may indicate liver damage.
Carbohydrate 19-9 Antigen (CA 19-9) CA 19-9 is a protein released by cancers of the pancreas and bile ducts. Levels are elevated in pancreatic cancer and cholangiocarcinoma. This test, while not specific enough to be used as a screening test, is best used as a tumor marker to determine response to chemotherapy. Often physicians will order this before initiation of therapy and then periodically during chemotherapy to determine progress.
Carcinoembryonic Antigen (CEA) Elevated CEA levels are suggestive, but not diagnostic of cancer, since elevated levels can occur in a variety of benign conditions such as smoking, pancreatitis and inflammatory bowel disease (IBD). CEA is best used as a monitor of progress during chemotherapy.