Chemotherapy, a common cancer treatment, can lead to elevated liver enzymes, a recognized side effect often called hepatotoxicity. While this might be concerning, these elevations are frequently monitored and managed by healthcare teams. This article will explore the liver’s functions, what elevated liver enzymes indicate, how chemotherapy can affect liver health, and the approaches taken when these enzyme levels rise during treatment.
The Liver’s Role and What Liver Enzymes Indicate
The liver, located in the upper right abdomen, performs many functions. It plays a central role in metabolism, converting nutrients from food into usable substances like glucose and proteins. The liver also detoxifies, filtering harmful substances from the bloodstream. Additionally, it synthesizes proteins necessary for blood clotting and maintaining fluid balance.
Liver enzymes are proteins that facilitate chemical reactions within liver cells. When liver cells are damaged, these enzymes can leak into the bloodstream, leading to elevated levels detected in blood tests. The most commonly monitored enzymes include Alanine Aminotransferase (ALT), Aspartate Aminotransferase (AST), Alkaline Phosphatase (ALP), and Gamma-Glutamyl Transferase (GGT).
Elevated ALT and AST levels suggest direct liver cell injury, as these enzymes are predominantly found within hepatocytes. Conversely, elevated ALP and GGT indicate issues with bile flow, such as cholestasis, or damage to the bile ducts. Normal ranges for these enzymes are: ALT (4-36 U/L), AST (8-33 U/L), ALP (44-147 U/L), and GGT (5-40 U/L).
How Chemotherapy Can Affect Liver Health
Chemotherapy drugs target and destroy rapidly dividing cancer cells, but they can also affect healthy cells, including those in the liver. The liver is susceptible because it is the primary organ responsible for metabolizing many chemotherapy agents. This interaction can lead to various forms of liver injury, known as hepatotoxicity.
One mechanism of injury is direct cellular toxicity, where chemotherapy drugs directly damage liver cells (hepatocytes). This can result in inflammation (hepatitis) or an accumulation of fat (steatosis). Examples include methotrexate and anthracyclines like doxorubicin. Other classes, such as alkylating agents (e.g., cyclophosphamide, busulfan) and platinum agents (e.g., cisplatin, oxaliplatin), can also induce direct hepatocyte injury.
Another way chemotherapy can impact the liver is through cholestasis, involving impaired bile flow. This occurs when the liver’s ability to produce or excrete bile is hindered, leading to a buildup of bile components in the blood. Some chemotherapy drugs can affect the small bile ducts within the liver, causing a cholestatic pattern of enzyme elevation.
Additionally, veno-occlusive disease (VOD), also called sinusoidal obstruction syndrome (SOS), is a condition where small blood vessels within the liver become blocked. This condition is associated with high-dose chemotherapy regimens, particularly those used before stem cell transplants, and can lead to symptoms like jaundice and painful liver enlargement. Drugs like cyclophosphamide and oxaliplatin have been linked to VOD. The severity and type of liver damage can vary depending on the specific chemotherapy drug, dosage, and individual patient factors like pre-existing liver conditions.
Responding to Elevated Liver Enzymes During Chemotherapy
Elevated liver enzymes during chemotherapy are detected through routine blood tests, regularly performed to monitor organ function and treatment tolerance. Often, these elevations may not cause noticeable symptoms, and the patient may feel well. However, if liver damage is more significant, individuals might experience symptoms such as fatigue, nausea, abdominal pain, or a yellowish tint to the skin and eyes (jaundice). Dark urine and light-colored stools can also indicate issues with bilirubin processing.
When elevated liver enzymes are identified, the medical team evaluates the situation to determine the cause and appropriate course of action. This might involve additional diagnostic tests to rule out other potential causes of liver dysfunction, such as infections or other medical conditions. Management strategies are tailored to the individual and the extent of the enzyme elevation.
Options include closer monitoring of liver function tests to observe trends. In some cases, the chemotherapy drug dose may be adjusted, or treatment might be temporarily paused to allow the liver to recover. Discontinuation of the offending agent may be necessary if the elevation is severe or persistent. Supportive care measures may also be implemented to help protect the liver or manage symptoms. The goal is to balance the effectiveness of cancer treatment with the need to protect the patient’s liver health.