Fatigue is a common symptom among liver disease patients and is frequently experienced by many people in daily life. We often hear them say, "I've been so tired lately" or "I feel completely exhausted." This symptom is not only present in patients with abnormal liver function but can also affect those with normal liver function, though the severity of fatigue may vary from person to person. So, what exactly does fatigue feel like? Why do patients with normal liver function also experience fatigue?

I. What Is Fatigue?

Fatigue, or weariness, is a term used to describe a subjective feeling of weakness: the patient feels it difficult to initiate activities, or has the desire to act but is unable to start, or has weak endurance for activities, or feels extremely tired after only slight exertion. Sometimes it also refers to neurological fatigue caused by difficulty concentrating, poor memory, and emotional instability.

2. Why Fatigue Occurs Even When Liver Function Is Normal

Regardless of whether liver function is normal or not, the symptom of fatigue in liver disease patients cannot be ignored. The main factors contributing to fatigue in patients include:

1. During hepatitis flare-ups, due to reduced appetite, insufficient caloric intake, and lack of energy required for activities—for example, some liver disease patients may experience hypoglycemia or hypoalbuminemia.

2. Damage to the liver's hepatocytes leads to a decrease in the serum levels of synthesized cholinesterase, causing dysfunction in neuromuscular transmission. This manifests as inhibition at the neuromuscular junction during movement or excitement, making the individual appear less willing to engage in physical activity.

3. During hepatitis, impaired bile secretion and excretion result in a deficiency of bile in the intestines, leading to poor absorption of fat-soluble vitamin E. A deficiency in vitamin E can cause nutritional muscular atrophy and weakness.

4. In patients with liver disease, the conversion of lactic acid produced during muscle activity into liver glycogen is impaired. This causes an excessive accumulation of lactic acid in the muscles, leading to muscle soreness, which often affects muscle strength. Some patients may not experience significant soreness and instead exhibit fatigue characterized by an unwillingness to engage in physical activity.

While elevated transaminase levels do indicate liver damage, normal liver function does not necessarily mean the liver is free from issues. The liver has a strong compensatory capacity, and in the early stages of damage, its own compensatory mechanisms may prevent abnormal liver function from becoming apparent. Therefore, assessing liver damage requires a comprehensive analysis that includes blood tests, imaging studies, as well as the patient's symptoms and physical signs.