Overview and Causes of Toxic Liver Injury

The liver is the body’s chemical factory. It supplies nutrients to the body from the components obtained from all the food we eat, and it breaks down and detoxifies unnecessary and harmful substances. Because of this characteristic, most other organs receive blood supply only from the arteries, but the liver has a unique structure with blood supply from two sources: the hepatic artery and the portal vein.

As the body’s chemical factory, the liver performs essential roles such as synthesizing various proteins, including albumin in the blood, regulating blood sugar, synthesizing lipids such as cholesterol, and converting and detoxifying internal and external substances. However, all drugs we take to recover from disease are both medicines with beneficial effects and poisons with side effects. Therefore, even substances taken for the body’s benefit may cause toxic effects if used at inappropriate doses, or in some cases regardless of dose.

This characteristic applies without exception not only to western medicine but also to all substances people ingest, including food and herbal medicine (herb medicine). Thus, liver damage can occur due to food and drugs we consume. Toxic liver injury caused by drugs and food can appear in a wide range of clinical forms, from asymptomatic cases to acute fulminant hepatitis, and the prognosis is also very diverse, ranging from simple abnormalities in blood chemistry tests to cirrhosis and liver tumors. However, such toxic liver injury is not easy to diagnose or prevent. This is because there is no special marker that can diagnose toxic liver injury, so it can only be diagnosed after excluding many other possible causes of liver damage. In addition, because toxic liver injury appears as an individual metabolic idiosyncratic reaction, whether it develops differs from person to person even with the same drug or food, and even in one individual, the occurrence and timing of liver injury are not consistent.

Cause

For drugs and food entering the body to act as the medicinal and nutritional components we want, they must undergo a process of metabolic conversion in the liver in most cases. This process involves complex chemical reactions, and toxic liver injury occurs when the metabolic conversion process of a particular drug or food exceeds the liver’s capacity, or when the liver cannot properly perform this function.

Toxic liver injury is divided into direct toxic liver injury, which can occur in anyone when the amount of toxin entering the body increases, and hypersensitivity-related liver injury, in which toxic liver injury occurs in some people but not in others even with the same amount. However, when severe liver injury occurs, these two mechanisms often act together.

1. Direct toxic liver injury: Liver injury occurs in anyone when the amount entering the body increases
2. Hypersensitivity-related liver injury: Sensitivity differs from person to person even when the same amount enters the body

One thing that makes it difficult to classify the causes of toxic liver injury in Korea is herbal medicine. At present, in Korea, herbal medicine is manufactured through various channels not only by Korean medicine doctors but also by herbal pharmacists, pharmacists, and others, and some herbal materials are imported and used by the public without proper control and management.

In addition, folk remedies are so common that the distinction between herbal medicine and folk remedies is often unclear. Therefore, in Korea, the causes of toxic liver injury are broadly classified into (prescription) drugs, herbal medicine, health functional foods, and folk remedies. Representative prescription drugs that can cause toxic liver injury include acetaminophen (Tylenol), tuberculosis medications (isoniazid), antifungals (oral edema medications, etc.), antibiotics, general anesthetics, and neuropsychiatric drugs. When prescribing these medications, careful observation and follow-up testing are necessary to determine whether toxic liver injury occurs.

So far, I have explained the overview and causes of toxic liver injury. In the next part, we will look at symptoms and treatment of toxic liver injury.

Source: Korea Disease Control and Prevention Agency, National Health Information Portal