IVER FUNCTION TESTS (LFTS) :-
■ Normal LFT’s do not exclude the possibility of chronic liver disease.
■ typical set of LFTS will include:
- ALANINE – AMINOTRANSFERASE(=ALT =SGPT) –
● Normal (5-45 U/L)
● high level suggests----- viral or drug induced hepatitis, or extensive hepatitis with necrosis of another source.
●Normal levels in infants are 2-times that of adults
● Found mainly in liver
● It is fairly specific for liver damage.
●Levels will be raised before jaundice appears.
● Levels of ALT fluctuate slightly throughout the day, and are particularly raised after exercise.
● It is generally raised in liver problems, and less so in problems with the bile duct. It may also be raised in heart problems.
● More specific for liver damage than AST.
●Levels of ALT and AST both raised above 2x normal then this is significant.
●If transferases are very high (greater than 1000 U/L) then the diagnosis is almost certainly hepatitis
● Alcoholic liver disease will never cause an AST of >1000 u/L
- ASPARTATE TRANSAMINASE (=AST =serum glutamic oxaloacetic transaminase (SGOT)
● Normal ( 5-45 U/L )
●Raised in— viral hepatitis, severe skeletal muscle trauma, extensive surgery, drug induced hepatic trauma,
●Levels from 10-20x normal may suggest MI, and alcoholic cirrhosis.
●5-10x normal may suggest chronic cirrhosis
● Mildly raised levels are often found it fatty liver (steatosis), liver metastasis and PE.
●These enzymes are found in the liver, RBC’s, cardiac and skeletal muscle, kidney and brain tissue. As a result, damage to any of these areas can result in an increased level on test result.
● Remember, high levels are likely to be liver OR heart problems OR muscle damage .
- ALKALINE PHOSPHATASE (=ALP) -
●Normal (25-110 U/L )
● found in cells lining bile duct and in bone.
●physiologically elevated level in high bone turnover(=adolescence ) and in third trimester of pregnancy.
● largely elevated in bile duct blockage, and slightly raised in liver disease (e.g. hepatitis or liver cancer)
- GAMMA-GLUTAMYL TRANSPEPTIDASE GGT)
●Normal (<65 U/L )
● more sensitive marker for cholestatic damage than ALP, Gamma glutamyl transpeptidase (GGT)
●Raised levels ---- in obstruction of the bile ducts.
●GGT is often used to confirm that AST readings are due to liver damage.
● used to monitor cirrhosis caused by alcoholism.
●Normal (0.1–1.0 mg/dL)
● Most commonly used to asses for obstructive jaundice.
● raised in liver damage and in cases of severe RBC damage.
●Test for urobillogen can be useful in determining whether it is due to RBC’s or a problem with the liver / bile system.
- ALBUMIN –
●Normal (3.5 to 5.3 g/dL)
●major protein constituent of plasma, and accounts for over 50% of all plasma proteins.
●It is manufactured in the liver from ingested amno-acids. It helps to regulate osmotic pressure as well as transport nutrients and waste products.
- albumin —2 weeks
- pre-albumin -----2 days
● It may often be reduced as a result of;
INR (=INTERNATIONAL NORMALIZED RATIO)
● INR are measures of the extrinsic pathway of coagulation.
●also called “ProTime INR” and “INR PT”.
● used to determine the clotting tendency of blood, in the measure of warfarin dosage, liver damage, and vitamin K status.
●specific for cholestasis or damage to the intra or extrahepatic biliary system
●used as a substitute for GGT for ascertaining whether an elevated ALP is of biliary or extra-biliary origin.
ALP raised, ALT slightly raised – likely to be a problem in bile duct.
ALT raised, ALP slightly raised – likely to be a problem in liver.
Very high ALT, slightly raised AST – suggests viral / drug induced / sever necrosis of liver
ASP raised, ALT slightly raised – suggests alcoholic or drug induced cirrhosis.
RATIO OF AST AND ALT CAN BE USEFUL IN DIFFERENTIAL:-
■ ALT is more specific for liver damage than AST
- AST: ALT =1
Associated with ischaemia (CCF and ischaemic necrosis and hepatitis)
- AST: ALT >2.
a. Associated with Alcoholic hepatitis
b. Alcohol induced deficiency of pyridoxal phosphate
- AST: ALT <1
a. High rise in ALT specific for Hepatocellular damage
b. Paracetamol toxicity with hepatocellular necrosis
c. Viral hepatitis, ischaemic necrosis, toxic hepatitis