Liver Function Tests - Cancer Science

What are Liver Function Tests?

Liver function tests (LFTs) are a group of blood tests that assess the health and functionality of the liver. They measure the levels of various enzymes, proteins, and substances produced or processed by the liver. These tests are crucial for diagnosing and monitoring liver diseases, including those related to cancer.

Why are Liver Function Tests Important in Cancer Patients?

In cancer patients, LFTs are essential for several reasons. First, they help in diagnosing liver metastasis, where cancer cells spread from their original site to the liver. Second, they monitor the liver's ability to process medications, especially chemotherapy drugs, which can be hepatotoxic. Lastly, LFTs can assess the overall liver health, which is critical for maintaining the body's metabolic balance.

What Specific Tests are Included in Liver Function Tests?

LFTs typically include the following tests:

Alanine Aminotransferase (ALT): This enzyme is found mainly in the liver. High levels suggest liver damage.
Aspartate Aminotransferase (AST): This enzyme is found in the liver and other organs. Elevated levels indicate liver or muscle damage.
Alkaline Phosphatase (ALP): High levels can indicate liver disease or bone disorders.
Gamma-Glutamyl Transferase (GGT): Elevated levels can suggest bile duct problems or liver disease.
Bilirubin: High levels of this yellow pigment can indicate liver dysfunction or hemolysis.
Albumin: Low levels can suggest liver disease or malnutrition.
Total Protein: This measures the total amount of protein in the blood, including albumin and globulin.

How are LFTs Interpreted in Cancer Patients?

Interpreting LFTs in cancer patients involves considering the context of the patient's overall health and cancer type. Elevated ALT and AST levels could indicate liver damage from metastasis or treatment toxicity. High ALP and GGT levels might suggest obstruction or liver metastasis. Elevated bilirubin could indicate severe liver dysfunction or bile duct obstruction. It's essential to correlate LFT results with imaging studies and clinical findings for accurate diagnosis and management.

What are Normal Ranges for Liver Function Tests?

Normal ranges can vary slightly depending on the laboratory, but generally, they are as follows:

ALT: 7-56 units per liter
AST: 10-40 units per liter
ALP: 44-147 units per liter
GGT: 9-48 units per liter
Total Bilirubin: 0.1-1.2 mg/dL
Albumin: 3.5-5.0 g/dL
Total Protein: 6.3-7.9 g/dL

Abnormal results require further investigation and correlation with clinical findings.

What are the Limitations of Liver Function Tests in Cancer?

While LFTs are valuable, they have limitations. They are non-specific and can be elevated due to various reasons, not just cancer. Conditions like hepatitis, fatty liver disease, and drug toxicity can also cause abnormal LFTs. Therefore, LFTs should be part of a broader diagnostic approach, including imaging and biopsy if necessary.

How Often Should LFTs be Monitored in Cancer Patients?

The frequency of LFT monitoring depends on the type of cancer, treatment plan, and the patient's overall health. In patients receiving hepatotoxic treatments like chemotherapy, LFTs might be monitored before each cycle. For those with known liver metastasis, regular monitoring helps assess disease progression and liver function.

What Happens if Liver Function Tests are Abnormal?

If LFTs are abnormal, further evaluation is necessary. This may include imaging studies like ultrasound, CT scan, or MRI to assess the liver's structure. A liver biopsy might be performed to obtain a tissue sample for histological examination. Depending on the findings, treatment plans may be adjusted, including modifying or discontinuing hepatotoxic drugs.

Conclusion

Liver function tests are a critical tool in the management of cancer patients. They provide valuable information about liver health, treatment effects, and potential complications. However, they should be interpreted in conjunction with other diagnostic tools and clinical findings for accurate assessment and optimal patient care.