There are dozens of diseases that affect the liver. The two most common causes of liver diseases are viral infections and drugs. Though there are different causes of liver diseases, the clinical signs and symptoms are divided in to two categories.

Due to liver cell damage

Due to obstruction to bile flow

Signs and symptoms due to liver cell damage:

In liver cell damage there is defective synthesis of proteins and defective detoxification. The signs and symptoms include

Jaundice

Dark urine

Vague abdominal pain

Loss of appetite

Fever occasionally

Bleeding

Fluid collection - Late manifestation

Brain, lung and kidney dysfunction in the final stages

Signs and symptoms due to obstruction to bile flow:

In bile flow obstruction there is defective excretion from the liver and defective absorption of fat and fat soluble vitamins from the intestines. The signs and symptoms include

Jaundice

Itching

Bleeding

Pale stools

Dark urine

Vitamin A,D,E and K deficiency

Common Liver Diseases:

Viral hepatitis:

Among the different viruses that affect the liver, the most significant ones are the hepatitis viruses. The types of hepatitis viruses affecting the liver are Hepatitis A, B, C, D and E. Of these, the Hepatitis B infection is the most dangerous. Hepatitis B virus infection is acquired by sexual contact and by blood transfusion. It damages the liver cells and causes minimal bile flow obstruction. There are a few drugs which can control the disease to a certain extent, including lamivudine and interferon. The complications of a hepatitis B infection include cirrhosis and liver cancer. There are however, vaccines available to prevent Hepatitis B and A infections.

Drug induced hepatitis:

Some drugs can cause liver damage either in the normal doses or in higher than normal doses. These drugs can cause liver cell damage or bile flow obstruction, depending on the medication. Some of the common drugs implicated in liver damage are

Anti TB drugs like INH, rifampicin and pyrizinamide

Antibiotics like erythromycin

Anesthetic drugs like halothane

Anti pyretics like paracetamol ( in high doses)

Cirrhosis:

Cirrhosis is condition characterized by irreversible damage to liver cells. The cells are destroyed and are replaced by non-functioning nodules. Some of the causes of cirrhosis are chronic alcohol intake, hepatitis B and C infection, hemochromatosis, Wilson's disease and alpha 1 anti trypsin deficiency. Cirrhosis later leads to cancer liver.

Liver Cancer:

Cancer liver is fatal condition affecting the liver. There are different types of liver cancer. The most common one being the HCC or the hepatocellular carcinoma. HCC is a final complication of cirrhosis.

Some of the other diseases affecting liver are

Tuberculosis

Connective tissue disorders

Blood malignancies

Malaria

Evaluation of patients with liver disease should be directed at

(1) Establishing the etiologic diagnosis

(2) Estimating the disease severity (grading)

(3) Establishing the disease stage (staging).

Diagnosis should focus on the category of liver disease, such as hepatocellular versus bile flow obstruction injury, as well as on the specific etiologic diagnosis. Grading refers to assessing the severity or activity of disease - active or inactive, and mild, moderate, or severe. Staging refers to estimating the place in the course of the natural history of the disease, whether acute or chronic; early or late; pre-cirrhotic, cirrhotic, or end-stage.