Liver function tests - Kumar Flashcards
What is serum albumin a marker of?
- Synthetic function
- Gauging severity of chronic liver disease
- Falling albumin is a poor prognostic sign
Why is interpretation of low albumin difficult?
- Many other causes of hypoalbuminaemia
* Malnutrition / urinary protein loss / sepsis
When is differentiation between conjugated or unconjugated bilirubin important?
- In congenital disorders of bilirubin metabolism
* Or to exclude haemolysis
What is prothrombin time a marker of?
•Synthetic function
Why is prothrombin time a sensitive marker of both acute and chronic liver disease?
• It has a short half-life
How is vitamin K deficiency excluded as a cause of a prolonged prothrombin time?
•By giving an IV bolus (10mg) of vitamin K.
When does vitamin K deficiency commonly occur?
• binary obstruction: low conc. of bile salts = poor absorption of vitamin K
What two transaminases are contained hepatocytes and leak into the blood with liver cell damage?
- Aspartate aminotransferase
* Alanine aminotransferase
What is more specific to the liver, AST or ALT?
- ALT is more specific
* (AST is also present in heart, muscle, kidney and brain)
High levels of AST may indicate what conditions?
• Hepatic necrosis / myocardial infarction / muscle injury / congestive cardiac failure
What does a rise in ALT indicate?
• ONLY liver disease
In viral hepatitis what is the ALT: AST ratio?
- ALT > AST
* UNLESS cirrhosis is present, in which case AST > ALT
In alcoholic liver disease what is the ALT: AST ratio?
•AST > ALT
In patients with liver disease without cirrhosis and have AST > ALT what is likely astrological agent?
•Alcohol or obesity
Where is alkaline phosphatase present?
- Hepatic canalicular and sinusoidal membranes
* Bone / intestine / placenta
Abnormal ALP is presumed to be from the liver when what other abnormal finding is present?
• Abnormal gamma-GT
What happens to serum ALP levels in both intrahepatic and extra hepatic cholestatic disease?
• It is raised due to increased synthesis
What has happens to serum ALP levels as result of hepatic infiltrations and cirrhosis?
- Raised
* (frequently in absence of jaundice)
What are the two likely causes for very high ALP serum levels (>1000IU/L)?
•Hepatic metastases and PBC
What liver biochemistry marker can be a useful indicator of alcohol intake?
• gamma-GT
Is a slightly raised gamma-GT in the absence of other abnormal liver function markers a cause for concern?
- No
* Mild elevations of gamma-GT are common. Can occur with minimal alcohol consumption.
In cholestasis, why do gamma-GT and ALP levels rises in parallel?
•They have a similar pathway of excretion
What occurs to the globulin fraction in autoimmune hepatitis?
- It is raised
* (if it falls it indicates successful therapy)
What does thrombocytopenia suggest (<150 x10^9/L)?
• Indicative of cirrhosis, unless another cause can be found.
In alcohol excess how do RBCs often present?
• Macrocytic
What does high levels of alpha-fetoprotein in non-pregnant adults suggest?
- Hepatocellular carcinoma
* Slightly raised with regenerative liver tissue in patients with hepatitis, chronic liver disease and teratomas
What does high levels of serum and amniotic alpha-fetoprotein in pregnancy suggest?
• Fetal neural tube defects
Raised urinary copper, and low serum copper and caeruloplasmin indicate what disease?
•Wilson’s disease
