Viral Hepatitis Pathophysiology

 

NORMAL LIVER FUNCTION

The liver is one of many organs that aids in digestion and nutrition. It is located under the right diaphragm and is divided into right and left lobes. The liver weighs approximately 1.2 to 1.6 kg and is the largest organ in the body. It produces bile which is utilized for fat emulsification and absorption (McCance & Huether, 2019). The liver is a highly vascular organ. It has many metabolic and immune functions (McCance & Huether, 2019). For example, the liver converts glucose during fasting and stores glycogen as muscle fuel. It produces plasma proteins and filters and detoxifies the blood by removing and harmful or toxins from the body. Also, the liver receives nutrients then metabolizes or synthesizes them into forms that the body’s cells can absorb. In addition, the liver removes ammonia from the body and converts it to urea that excreted by the urine (Berkowitz, 2007).

Figure 1. Anatomy of Liver (John Hopkins, 2019).

Unfortunately, when there is liver failure or damage to the liver cells; many areas in the body are affected. The body will have an increased risk of bleeding due to decreased in protein production. Fasting hypoglycemia may occur due to decrease in gluconeogenesis. A decrease

in detoxification reaction may cause a buildup of toxins in the blood which can lead to hepatic encephalopathy. Lastly, jaundice may occur because of the failure of the liver to secrete conjugated bilirubin (Berkowitz, 2007).

Figure 2. End Stage Liver Disease (UCSF, 2019).

PATHOPHYSIOLOGY OF THE LIVER AND VIRAL HEPATITIS

Viral hepatitis is a disease which initially affects the liver. Hepatitis has several different routes of transmission and comes in several different forms such as Hepatitis A, B, C, D and E. It is triggered by many microorganisms such as cytomegalovirus (CMV), Epstein-Barr virus (EBV) and Herpes Simplex virus (HSV) (McCance & Huether, 2019). Below are more details on the pathophysiology of disease.

Viruses enter the blood stream and spread to the liver. They infect the hepatocytes and multiply. They change the antigen structure on the virus site. The body begins to use self-mediated immune response attempting to damage the hepatocytes. In Hep B and C, they can continue this process over and over for years.

STAGES OF VIRAL HEPATITIS

There are three stage of symptoms: prodromal, icteric and convalescent. Based on which phase the patient is in, the symptoms will vary. In the prodromal stage, the virus is in the blood and will release chemicals. These chemicals will create symptoms such as fever, headache, fatigue, nausea, vomiting, skin rashes and joint pains. In the icteric stage, conjugated bilirubin and transaminases spills into the blood because of damage of bile ducts and hepatocytes. The conjugated and unconjugated bilirubin make the patient appear yellow and present with dark urine. The liver may become enlarged in this state as well which is termed hepatomegaly. In the convalescent stage, the symptoms become better or the patient returns to normal (McCance & Huether, 2019).

HEPATITIS A

Hepatitis A is a RNA virus of the family Picornaviridae. It has a 30 to 50 day incubation period. The virus is secreted for 2 weeks prior to the appearance of symptoms and up until 3 months later. It is spread via fecal/oral route, transfusion of blood or men having sex with men. It is highly contagious and is prevalent in crowded areas, unsanitary areas and areas with contaminated food and water. The symptoms appear like food poisoning symptoms. The severity is mild and the disease is not chronic. Vaccination is available and typical given with Hepatitis B vaccine to improve outcomes. The best prevention is washing hands, wearing gloves and keeping meticulous hygiene (McCance & Huether, 2019).

HEPATITIS B

Hepatitis B a DNA virus with 8 different genotypes. It has a 3 to 8 week incubation period. It is transmitted parenterally, sexually or through mother to baby. Mother to baby occurs only if the mother was exposed to the virus during the third trimester of pregnancy. The disease can cause liver injury low grade fever, inflammation, risk for Hepatitis C, risk for cirrhosis, risk for liver failure and risk for hepatocellular carcinoma. The disease could be severe and chronic. Treatment is with nucleotide analogs and interferons and a preventative vaccination is available (McCance & Huether, 2019).

HEPATITIS C

Hep C is a RNA virus with 10 different genotypes. It has a 40 day incubation period. It is spread via parenteral route. Sometimes there may not be any symptoms to aid in diagnosis but liver enzymes will be elevated. It can increase the risk for chronic liver disease, cirrhosis, hepatocellular carcinoma, esophageal varices and potential need for liver transplant. Severity is mostly mild. Treatment is with antivirals drugs and sometimes drug resistance can develop when disease becomes more severe. There is no vaccination. The CDC says that people who are born from 1945 to 1965 should be screened for the virus (McCance & Huether, 2019).

HEPATITIS D

Hepatitis D is a defective single stranded RNA virus and usually occurs with Hepatitis B. It is spread parenterally. Drug users are most at risk. It could be mild or severe and lead to liver failure. Treatment is with pegylated interferon alpha and treatment has a high failure rate (McCance & Huether, 2019).

HEPATITIS E

Hepatitis E is a RNA virus in the family Hepeviridae. It has a 50 day incubation period. It is spread via fecal oral route, through contaminated water or uncooked meat. It is most common in Asia and Africa. The severity is mild and disease is usually not chronic but if severe enough can lead to acute liver failure of chronic hepatitis. It resembles Hepatitis A but could be asymptomatic. It can produce neurological symptoms and impair kidney function. Treatment is with ribavirin and pegylated interferons (McCance & Huether, 2019).