LFTs Flashcards
What are the homeostatic functions of the liver?
Gluconeogenesis Protein metabolism. Fat metabolism Bilirubin metabolism. Acid/Base Balance. Heat production.
What is stored within the liver?
Glycogen. Iron. Fat. Vitamins A, B12, D, E, K. Copper and Selenium.
What are the metabolic functions of the liver?
Amino acid metabolism creates Ammonia
Ammonia + CO2 = UREA
UREA excreted renally.
Nucleoprotein from worn out cells is broken down to form uric acid, which is renally excreted.
The liver processes hormones such as insulin, glucagon, oestrogens and growth hormones.
It is the most important site for the metabolism of drugs and alcohol. Fat-soluble drugs are converted to water-soluble substances to facilitate excretion in bile or urine.
what are the synthetic functions of the liver
Albumin. Coagulation factors. Acute Phase Proteins. Vitamin A (but not in the building it sense) Bile.
Define Pre-Hepatic Jaundice
Increased destruction of red blood cells = increased amounts of bilirubin.
red cell abnormalities (sickle cell), hemolysing diseases such as malaria, very rarely drugs such as levodopa, NSAIDs and some antibiotics.
Define Hepatocellular Jaundice.
Results from the livers inability to transport bilirubin into bile. Causes are related to liver cell damage. For example alcohol use, hepatitis, potential certain drugs (salicylates, oral contraceptives, rifampicin).
Define post hepatic jaundice
Obstructive Jaundice.
Results from obstruction to the excretion of bilirubin.
Causes of large duct obstruction include gallstones, biliary duct strictures, sclerosing cholangitis (inflammation of the bile ducts) and carcinoma (particularly head of pancreas).
Causes of small duct obstruction include, damage to liver cells (by drugs and alcohol), viral hepatitis, bacterial infections and primary biliary cirrhosis.
Define Hepatitis
Inflamation of the liver with accompanying liver cell damage or death. Associated with viral infection, certain drugs or auto-immune
symptoms of hepatitis
Symptoms include jaundice, nausea, vomiting, loss of appetite, tenderness in the right upper abdomen, aching muscles, and joint pain. In severe cases, liver failure may result.
Define Cirrhosis
chronic damage to liver cells and the eventual formation of scar tissue (fibrosis).
Symptoms of cirrhosis
mild jaundice, oedema, confusion and haematemasis.
What causes a rise in ALT/AST
Hepatitis (viral or auto-immune) Excessive alcohol intake or alcohol related liver disease Liver inflammation. Inherited liver diseases Liver tumours Heart failure
What is ALT
Alanine aminotransferase (ALT)
an enzyme necessary for energy production.
It is present in a number of tissues, including the liver, heart, and skeletal muscles, but is found in the highest concentration in the liver.
What conditions would you expect a significant rise in ALT
The highest ALT levels are associated with acute and massive liver cell necrosis. E.g acute viral hepatitis, acute shock, paracetamol OD)
A persistent moderately raised ALT (10 x normal) is associated with chronic liver disease.
What is AST
Aspartate aminotransferase (AST)
] is also necessary for energy production
It is found primarily in the liver, but is in other organs as well. High levels in the blood can indicate liver disease, but may also indicate other systemic diseases.
What causes a rise in ALP and GGT
Primary biliary cirrhosis, Fatty liver (steatosis), Alcoholic liver disease, Liver inflammation, Liver tumours, Gallstones or gall bladder problems.
Define ALP and GGT
GGT and ALP are also called cholestatic liver enzymes. Chloestasis is a term used for partial or full blockage of the bile ducts. If the bile duct is inflamed or damaged, GGT and ALP back up into the liver and then the blood.
What is GGT
Gamma-glutamyltranspeptidase (GGT) is found in the liver. The normal range is 5 – 80 U/L. GGT levels may be elevated in patients taking phenytoin and can be lower in those taking oral contraceptives.
Elevated GGT levels are induced by alcohol so it can be used to monitor alcohol abuse (in the absence of liver disease)
What is ALP
Alkaline phosphatase (ALP) is formed in the bones, intestines (cells lining the bile duct), kidneys and placenta as well as the liver.
What is ALP
Alkaline phosphatase (ALP) is formed in the bones, intestines (cells lining the bile duct), kidneys and placenta as well as the liver. Diseases of impaired bile formation - cholestatic
If ALP is raised but GGT is normal
Bone disease or metastatic spread
What are the two forms of bilirubin
Unconjugated - formed in the spleen and is not water-soluble
Conjugated - soluble form, converted in the liver from the unconjugated form. Secreted into bile
What are the two forms of bilirubin
Unconjugated - formed in the spleen and is not water-soluble
Conjugated - soluble form, converted in the liver from the unconjugated form. Secreted into bile
What can cause a rise in bilirubin?
Haemolysis
Gilberts syndrome
Certain drugs - anabolic steroids, antibiotics, antimalarials, ascorbic acid, codeine, adrenaline, oral contraceptives, vitamin A
In split monitoring of bilirubin - what causes a rise in unconjugated bilirubin
Unconjugated (indirect-reacting) bilirubin. The normal is < 10 umol/L. Elevated levels of indirect reacting bilirubin are usually caused by haemolysis and impaired conjugation from liver cell dysfunction (e.g. hepatitis)
In split monitoring of bilirubin - what causes a rise in conjugated bilirubin
Conjugated (direct reacting) bilirubin testing measures bilirubin made in the liver. The normal value is < 7 umol/L. Elevated levels typically result from obstruction either within the liver (intrahepatic) or a source outside the liver such as gallstones or cancer of the pancreas.
Isolated rise in Bilirubin?
Gilberts syndrome
Haemolysis - specifically in patients with anaemia
Rise in ALP/GGT - Cholestatic
Common – Primary biliary cirrhosis, Primary sclerosing cholangitis, biliary obstruction, hepatic congestion, drug-induced liver injury
Isolated raised ALP may be Vit D deficiency
Rise in AST/ALT
Hepatic – predominantly raised ALT and AST indicate hepatocellular liver injury (hepatitis)
Common – viral, NAFLD, Alcohol-Related LD, AutoImmune Hepatitis, drug-induced
What are the causes of acute liver failure?
Viral Drugs and toxins Pregnancy Metabolic Other
Causes of chronic liver disease
Alcoholic liver disease Primary biliary cirrhosis Sclerosing cholangitis Post viral hepatitis Cryptogenic cirrhosis
What is the clinical significance of portal hypertension
Hypertension within the portal vein, causing back pressure within the abdomen
Portal hypertension leads to increased hydrostatic pressure leading to ascites, oedema and potential for oesophageal varices
NB. Ascites and oedema are also related to ;
Decreased renal blood flow = sodium and water retention.
Impaired synthesis of albumin = reduced osmotic pressure.
