What is liver?
Liver is one of the vital organs of our body with wide range of functions. The liver consists of highly specialized tissues that regulate a wide variety of biochemical reactions necessary for vital functions of our body.
Where is the liver located in our body?
The liver is located just beneath the right rib cage below the right diaphragm and the right lung. The lower border can be felt 2 cm below the right rib cage in infants and younger children. The liver is surrounded by right diaphragm, stomach, intestine (duodenum) and gall bladder.
What is the structure of liver?
Liver is a reddish brown pyramid shaped organ. It weighs around 150gms at birth and increases to 1200-1500 grams in adult. It is the largest internal organ. The liver is made of multiple cells which are called hepatocytes (liver cell) which is arranged to form lobule which is the functional unit of the liver. Within the lobule there are spaces between the hepatocytes which are called sinusoids through which the blood flows.
The liver gets a dual blood supply. Twenty percent of the blood supply comes from hepatic artery which is a branch of the celiac artery which arises from the aorta (main blood vessel arising from the heart). Eighty percent of the blood supply comes from portal vein. The portal vein carries blood containing digested nutrients from entire intestine, spleen and pancreas. The blood circulates in the liver through the sinusoids and then reaches the smaller veins which combine to form hepatic veins. There are three hepatic veins which drain the blood from the liver to the right side of the heart.
The liver is also the largest gland in the body. It produces bile juice which is important for digestion of fat in our food. The bile juice produced in the liver is collected in the small bile ducts (bile cannaliculi) which merge to form hepatic ducts (tube like structure for drainage). The right hepatic duct arises from the right lobe and the left hepatic duct arises from the left lobe of the liver. They join together to become the common hepatic duct which joins the duct from the gall bladder to become common bile duct. This duct finally drains into the first part of small intestine (duodenum). The gall bladder is a pear shaped organ which rest beneath the liver. The bile juice gets collected in the gall bladder and is released whenever the food enters the small intestine.
What are the functions of liver?
Liver performs a wide range of functions which are important for normal functioning of our body.
The liver has multiple synthetic functions. Liver is involved in the processing of the digested nutrients from our food which goes to the liver via the portal vein. This processing is called metabolism. The final products are used for the energy and growth of our body.
The liver produces various amino acids which are the building blocks of every cell in our body. Gluconeogenesis is the synthesis of glucose which maintains blood sugar level during the period in between the meals and during fasting. Liver also stores glucose released from digestion of carbohydrate in the diet in the form of glycogen. It breaks down glycogen which is the instant source of glucose especially during exercise. Liver is involved in metabolism of various amino acids to simpler nitrogen compounds so that it can be excreted by the kidneys.
Liver also produce cholesterol and triglycerides. Cholesterol helps in formation of bile juice.
It is the only organ producing protein called albumin as well as substances which prevent the blood from clotting. Liver stores important micronutrients like vitamin A, D, B12, iron and copper.
Liver helps in the detoxification (purification) of blood. It removes the unwanted substances absorbed from our food. It metabolizes drugs and toxins so that it is excreted either in the bile or via the kidneys. It converts ammonia which is produced from metabolism of proteins to urea which is easily excreted in the urine.
Liver is involved in the excretion of bilirubin which is produced from the breakdown of hemoglobin present in the red blood cells. Bilirubin is converted into a direct form (conjugated) which is excreted in the bile.
Liver is also important for the immune functions of our body. The kupffer cells present within the liver removes various bacteria and antigens absorbed from the intestine.
Liver releases thrombopoetin which regulates production of platelets by the bone marrow.
It controls blood pressure by playing a role in formation of angiotensin (hormone which increases BP). It also plays important role in the production of vitamin D. It metabolizes various hormones like insulin, steroid hormones and hence controls their levels in the body.
How does the liver get affected in disease?
The liver may get affected by any one of following process:
- Infections: common infections are viral hepatitis A to E;
- bacterial infections : typhoid, tuberculosis, brucellosis; parasitic infections : malaria and amoebiasis
- Intrauterine infection belonging to TORCH group can cause hepatitis (inflammation of liver)
- Metabolic disorder: Liver is involved in multiple metabolic processes. Genetic defects in any enzymes can result in abnormal biochemical products which can damage the liver. E.g: Wilson disease, Galactosaemia, Tyrosinemia, cystic fibrosis.
- Abnormal blood blow: abnormal formation of the hepatic veins can lead to back pressure within the liver and result in a disease known as Budd chiari syndrome. Diseases of the right side of heart can cause similar problems.
- Defect in excretion of bile: This can lead to cholestatic jaundice and biliary cirrhosis (permanent damage of the liver tissues)
- Neoplasms (Cancer): Leukemia (Blood cancer), Lymphoma (cancer of the lymphoid tissues), Hepatoma, hepatoblastoma (malignancy of the liver cells) and secondary malignant deposits in the liver
- Toxins and Drugs: Paracetamol over dosage is a common cause of liver failure. Certain herbal medications, phosphorous, mushrooms can damage the liver.
- Autoimmune diseases: Autoimmune hepatitis due to antibodies production by the immune system ( anti sm, anti LKM antibodies)
What are the clinical presentations of liver diseases?
The following are the common symptoms:
Yellowish discoloration of the eyes and/or urine (jaundice)
Vomiting, nausea and loss of appetite
Pain in the right side of abdomen
Distension of abdomen either due to enlargement of liver/spleen or collection of fluid in abdomen
Blood in vomitus or black colored stools
Pale colored stools
Altered mental status
What are the tests performed to evaluate liver diseases?
Multiple tests are available to evaluate liver diseases in children.
Liver enzymes: This simple blood test estimates the level of various liver enzymes like SGPT (ALT), SGOT (AST) and serum alkaline phosphatase (SAP). SGPT and SGOT increases when the liver cells (hepatocytes) are damaged while SAP increases when there is obstruction to the bile flow.
Bilirubin level: This is done to assess the severity of jaundice. This increases when there is liver dysfunction or there is bile outflow obstruction.
Prothrombin time: This assesses the clotting mechanism of blood. It gets prolonged in liver disorder as the synthesis of clotting factors decreases. This is important test as it is the first to get affected in liver disorder.
Serum albumin: It is one of the important proteins produced by the liver and it decreases in liver dysfunction especially in chronic liver diseases.
Viral markers: As viral infection of the liver is common, viral markers study is done to diagnose infection due to Hepatitis A, B, C and E virus.
Imaging studies: USG abdomen is the basic imaging study to evaluate the size, shape and texture of liver. USG can detect mass in the liver; bile duct and gall bladder problems; cavity containing pus (liver abscess); portal vein obstruction etc. CT scan and MRI are helpful in further detailed study of liver and bile tract.
Metabolic tests: Multiple enzyme tests are available to detect abnormality of various biochemical reactions due to genetic disorder.
Liver biopsy: This is done to assess the status of liver cells, surrounding tissues, signs of liver damage and cause and severity of liver damage.
When does one need a Pediatric Gastroenterologist?
Usually the initial evaluation of liver disease is done by the pediatrician (child specialist). He can manage common liver disorder like viral hepatitis A, liver abscess and bacterial infections. But diseases which have a longer course like Hepatitis B,C, Wilson disease, Budd chiari syndrome or difficult to manage conditions like blood in vomitus, metabolic disorder, liver failure, requirement of liver transplantation etc are best managed by pediatric gastroenterologists or hepatologist. Timely referral to specialized centre can help in early diagnosis and prompt management of liver disorder.
Which are the best centers for managing pediatric liver diseases in India?
- Sanjay Gandhi post graduate institute, Lucknow
- Apollo Hospital, New Delhi
- Institute of Liver and Biliary Sciences, New Delhi
- Sir Ganga Ram Hospital, New Delhi
- Medanta Hospital, Gurgaon
- Post graduate institute, Chandigarh
- Jaslok Hospital, Mumbai
- Wadia hospital, Mumbai
- Kanchi Kamakoti Childs Trust Hospital, Chennai
- PSG institute of Medical Sciences, Coimbatore
- Christian Medical College, Vellore
- Institute of Post-Graduate Medical Education and Research, Kolkata
- Calcutta Medical research institute, Kolkata