Liver Function Tests Flashcards by Tim Resch

What is the safe weekly alcohol limit?

0-21 units/wk for men
0-14 units/wk for women
Not drunk in 1/2 bouts
2-3 alcohol free days a week

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What are the signs and symptoms of Liver Disease?

Jaundice and Pruritis
Nausea/Vomiting
Hepatomegaly
Ascites
Dark urine and pale stools (cholestasis)
Spider naevi (alcoholic liver disease)

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What is the major infective cause of liver damage?

Viral hepatitis

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What are the major ADRs leading to liver damage?

Halothane
Paracetamol overdose
Clavulanic acid
Valproate
Amiodarone
Herbals

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What are the major lifestyle causes of liver disease?

Obesity

Alcohol abuse

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What cancerous conditions lead to liver disease?

Primary cancer

Secondary metastases

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What are the main factors measured in an LFT?

Hepatocellular
Obstruction
Synthetic Function
Bilirubin

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What values are measured when assessing hepatocellular health?

Alanine Aminotransferases (<45 iU/L)
Aspartate Aminotransferases (<50 iU/L)

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What values are measured when assessing obstruction?

Alkaline Phosphatase (39-117 iU/L)
Gamma-glutamyl transpeptidase/transferase (0-70 iU/L m, 0-40 iU/L f)

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What values are measured when assessing synthetic function?

Albumin (30-48 g/L)

INR (1-1.2)

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What are the normal values for Bilribuin?

5-17 umol/L

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Describe Bilirubin physiology

Produced from breakdown of RBCs
Haem-Biliverdin-Bilirubin
Liver conjugates, makes water soluble
Excreted as bile

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What is the main effect of increased levels of Bilirubin?

Jaundice

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When are levels of Bilirubin increased?

Bilary obstruction (cholestasis)
Hepatocellular damage
Haemolysis

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How is Bilirubin excreted?

5-10% as stercobilinogen in stools

Majority undergoes enterohepatic cycling

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When are the Aminotransferases raised?

Markedly raised in hepatocellular damage

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Which Aminotransferase is a more specific marker of liver damage?

Alanine Aminotransferase (ALT)

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What do levels of ALT >2x greater than upper limits correspond with?

Biopsy proven liver disease

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Where is Alkaline Phosphatase normally found?

Present in canalicular/sinusoidal membranes

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When is Alkaline Phosphatase raised?

Markedly raised in Cholestasis

What are Gamma Glutyltransferases?

Microsomal enzymes present in many tissues

When is Gamma Glutyltransferase raised?

Increased by induction
-Alcohol (even small amounts)
-Carbamazepine
-Barbiturates
-Phenytoin
-Rifampicin
Increased in cholestasis
Increased in cellular damage

What does Albumin represent?

Synthetic activity of Liver over the long term

What is the T1/2 of Albumin?

T1/2 = 16-24 days

What is the Prothrombin Time?

Measure of coagulation and synthetic activity

Does the Prothrombin Time indicate acute or chronic damage?

Both | Coagulation factors have a short half life

What LFT results would be typical of Acute Hepatitis?

``` ALT & AST - Increased ALP - Increased/Normal Bilirubin - Increased/Normal GGT - Increased/Normal Albumin - Normal INR - Increased/Normal ```

What LFT results would be typical of Cholestasis?

``` ALT & AST - Increased/Normal ALP - Increased Bilriubin - Increased GGT - Increased Albumin - Normal INR - Increased/Normal ```

What LFT results would be typical of Chronic Liver Disease?

``` ALT & AST - Increased/Normal ALP - Increased/Normal Bilirubin - Increased GGT - Increased Albumin - Decreased INR - Increased ```

What is Jaundice?

Hyperbilirubinaemia resulting in yellow colouration of the skin/sclera

What level of Bilirubin is found in Jaundice?

>35-50 umol/L

What further symptoms develop from Jaundice?

Pruritis | Nausea

What is Prehepatic Jaundice?

Jaundice occuring when water insoluble, unconjugated Bilirubin is produced faster than the liver can conjugate it

What are the main causes of Prehepatic Jaundice?

Haemoylsis/Haemolytic anaemias | Gilbert's Syndrome (reduced levels of UDP-glucuronosyl transferase)

What is Hepatocellular Jaundice?

Loss of transaminases Liver unable to conjugate Bilirubin Reduced Bilirubin excretion

What is Cholestasis?

Disorder where Bile cannot flow from the liver to the duodenum

What are the two types of Cholestasis?

Intrahepatic | Extrahepatic

Describe Intrahepatic Cholestasis

Cholestasis occurring within the liver - Primary bilary cirrhosis (autoimmune damage to bile ducts) - Hepatocellular damage - Pregnancy w/ unknown cause

Describe Extrahepatic Cholestasis

Cholestasis occurring outside the liver - Gallstones - Calcified head of pancreas

Describe Obstructive Jaundice

Jaundice caused by cholestasis Liver CAN convert insoluble-soluble bilirubin CANNOT excrete bilirubin in bile, only in urine

What are the signs/symptoms of Obstructive Jaundice?

GGT & ALP - Elevated Pale stools Dark urine Bilirubin in urine

What are the most common complications of liver disease?

Jaundice Ascites Encephalopathy

How does Jaundice present?

Nausea | Pruritis

How should Jaundice be treated pharmacologically?

Colestyramine

How does Ascites present?

Accumulation of fluid in the peritoneal cavity - Oedema - Sodium Retention - Portal Hypertension

How should Ascites be treated?

Sprinolactone + Furosemide + salt restriction

How does Encephalopathy present?

Changes in personality Disorientation Confusion/drowsiness

How should Encephalopathy be treated?

Neomycin/Metronidazole + Lactulose

What are less common complications of liver disease?

``` Impaired coagulation Gastric bleeding (Ranitidine) Bleeding oesophageal varices (B-Blockers, Octreotide) ```