

Part One: Tests that detect injury to hepatocytes (serum enzyme tests)
1. ALT/SGPT
Primarily marker of hepatocellular injury (most sensitive, more specific than AST),
Liver cell death —> leaks in blood.
No correlation with extent of damage.
A) High ALT (>15-20 times)
- Ischaemia (Much Higher) (Shock, hypotension, CCF, comes down rapidly)
- Viral hepatitis, Autoimmune
- Drug toxicity (PCM), Severe toxic hepatitis
- Acute budd chiary syndrome
- Liver – Chronic Liver disease (eg Chronic hepatitis)
- Cholestasis (with ALP, GGT)
- Cardiac –Severe hepatic congestion in cardiac failure
- Other: Muscle injury, Kidney injury
- Liver: Neonatal hepatitis
- Hemochromatosis
- Autoimmune hepatitis
- NASH, EHBA
- Alpha1-antitrypsin deficiency, Wilson’s disease
- Infection: Infectious mononucleosis
- Drugs: Almost any drug. (ATT, AED, Antibiotics, NASAIDS), PCM therapeutic doses.
Note: Drugs more likely to cause an asymptomatic abnormality in liver function.
2) AST/SGOT
Origin: Liver, cardiac, skeletal muscle, kidney, brain, pancreas.A) High AST (>20 times)
Reflects damage to the hepatic cell , but less specific for liver disease.
- Ischaemic liver injury(Shock, hypoperfusion)
- Acute viral hepatitis
- Drug induced hepatic injury
- CVS: (CCF)
- Infection: (Infectious mononucleosis)
- Liver: (Alcoholic cirrhosis)
- Liver: Chronic hepatitis Specially alcoholic
- Skeletal muscle: DMD, Dermatomyositis, Infl. B calf muscle myositis
- Blood: Haemolytic anaemia, haemolysis
- Liver; Fatty liver, Metastatic hepatic tumour
- Drugs: Almost any drug
Ratios between AST and ALT are useful in differentials
AST: ALT =1 (Equal rise)
1. Ischaemia ( Shock, hypoxia, hypoperfsion injury)
AST: ALT <1 ( More ALT, specific for Hepatocellular damage )
2. Viral hepatitis, toxic hepatitis, Cholestatic hepatitis
3. Chronic active hepatitis, NASH
AST: ALT >2.5 (More AST)
2. Wilsons disease, cirrhosis
3. Bile duct obstruction, Tumours
(Adults:Alcoholic liver disease)
WHY: Depletion of vitamin B6 in chronic alcoholics. ALT and AST both use B6 as a coenzyme, but the synthesis of ALT is more strongly inhibited by pyridoxine deficiency than is the synthesis of AST. Alcohol also causes mitochondrial injury, which releases the mitochondrial isoenzyme of AST.Asymptomatic Transaminitis
Slight AST or ALT elevations (within 1.5 × normal) do not necessarily indicate liver disease.
WHY: unlike the values in many other biochemical tests, AST and ALT levels do not follow a normal bellshaped distribution in the population.They have a skewed distribution characterized by a long “tail” at the high end of the scale.
3. ALKALINE PHOSPATASE (ALP)
Source: liver, bone, placenta and intestine
Result of increased synthesis of the enzymes by cells lining the bile canaliculli, in response to cholestasis (intra or extra-hepatic)
Primary value: cholestatic disorders (Even before a rise in bilirubin.)
# Increased ALP : (n: 30 – 120 IU/L)
1. Liver (Sensitive for biliary obstruction, cholestasis)
Intrahepatic/Extrahepatic cholestasis. (Highest levels)
EHBA (Marked rise)
Viral hepatitis
2. Renal: Renal failure
3. Infiltration: Hepatic metastasis, amyloidosis, granulomatous diseases
4. CVS: Heart failure (Milder)
5. Infections: Inf mononucleosis, Fungal infection (Marked rise)
6. Bone (Usually non-pathological in growing children)
Osteomalacia, Bone metastasis, Pagets disease (very very high)
Deficiency induced Ricket’s, Rapid bone growth
Hyperparathyroidism
7. Physiological: Pregnancy Released to serum from placenta in late pregnancy.
8. Blood type O and B: Released from small intestine after fatty meal.
1. Drugs: Cimetidine, furosemide, phenobarb (Enzyme induction )
2. CCF (Often associated with AST and ALT rise)
3. Diabetes
4. Hyperthyroidism
# Low ALP
- Malnutrition
- Zn deficiency
- Vit c Deficiency
- Hypothyroidism
- Pernicious anemia
- Congenital Hypophosphatasia
- Isoenzymes (60 types) of ALP can be separated by electrophoresis (Expensive)
- Raised GGT and 5′-nucleotidase , deranged LFT (Easy)
Note:ALP levels vary with age. ALP levels are generally higher in children and adolescents because of physiological osteoblastic activity.
Levels may be up to 3 times higher than in healthy adults, coinciding with periods of maximum bone growth velocity
Test Cholestatic Infiltrative Hepatocellular
AST, ALT > ALP Typical - -
ALP > AST, ALT - Typical -
Elevation ALP ,
normal AST, ALT levels - Typical Typical
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