Serum Enzymes Flashcards
What are the two main types of serum enzymes?
- Functional enzymes (e.g., coagulation enzymes)
- Cell-derived enzymes (released due to organ damage)
Why are serum enzymes clinically useful?
They help detect organ damage earlier than symptoms appear.
What is the most liver-specific enzyme?
ALT (Alanine Aminotransferase).
Which enzyme rises within 3–8 hours of a heart attack (MI)?
CK-MB (Creatine Kinase-MB).
Which enzyme is better than amylase for diagnosing pancreatitis?
Lipase.
What does a combination of ALP and GGT indicate?
Cholestasis (bile duct blockage).
What is the role of 5’-Nucleotidase (5’-NT)?
Differentiates liver vs. bone causes of high ALP.
Which enzyme is best for monitoring chronic alcoholism?
GGT & CDT (Carbohydrate-Deficient Transferrin).
What is the main function of Lactate Dehydrogenase (LDH)?
Converts lactate to pyruvate (glycolysis).
What is the difference between Creatine and Creatinine?
Creatine is a stored energy molecule, while creatinine is its waste product used to assess kidney function.
What is the best enzyme for detecting liver disease?
ALT (Alanine Aminotransferase).
What pattern of enzyme elevation is seen in hepatitis?
ALT & AST ↑↑, ALT > AST.
What is the enzyme pattern in alcoholic hepatitis?
GGT & AST ↑↑, AST > ALT.
Which enzymes indicate bile duct obstruction (cholestasis)?
ALP & GGT ↑↑.
What happens to enzyme levels in liver cirrhosis?
Moderate AST & ALT increase (irreversible damage).
Why should hemolysis be avoided in blood samples?
It falsely elevates LDH, AST, and ALT.
What enzyme rises in toxic or drug-induced hepatitis (e.g., paracetamol overdose)?
ALT & AST.
Why is ASAT (AST) no longer used for MI diagnosis?
More specific cardiac markers like Troponins & CK-MB are preferred.
What does a high ALP level in children indicate?
Normal bone growth.
Which enzyme is useful in monitoring liver metastases?
LDH-5.
What is the best early enzyme marker for a heart attack?
CK-MB (3–8 hours post-MI).
What enzyme is useful for retrospective MI diagnosis?
LDH (peaks at 10–72 hours).
Why should physical exercise be avoided before CK testing?
It can falsely elevate CK levels.
What enzyme is the gold standard for detecting MI today?
Troponins (TnI, TnT).
What enzyme is best for detecting muscle diseases like rhabdomyolysis?
CK-MM (>100,000 IU/L in severe cases).
A patient has chest pain for 6 hours. What enzyme should be tested?
CK-MB (rises within 3–8 hours).
What enzyme rises in hemolytic anemias and leukemias?
LDH.
What does an isolated AST elevation suggest?
Cardiac or muscle damage (e.g., MI, rhabdomyolysis).
A patient with chronic alcohol use has high GGT & CDT. What does this suggest?
Alcoholic liver disease.
What enzyme combination is best for differentiating muscle from liver injury?
AST, ALT (liver) vs. CK (muscle).
Which enzyme is better for diagnosing pancreatitis?
Lipase (more specific than amylase).
When does amylase increase besides pancreatitis?
Mumps & bowel obstruction.
A patient with suspected pancreatic cancer has elevated lipase. What does this suggest?
Possible pancreatic tumor.
What enzyme is best for diagnosing bone diseases (e.g., Paget’s, Rickets)?
ALP (Alkaline Phosphatase).
Why is 5’-NT useful in liver disease?
It helps differentiate liver from bone causes of high ALP.
A child has high ALP but no symptoms. What is the cause?
Normal bone growth.
What enzyme is elevated in prostate cancer?
PSA (preferred over Prostatic Acid Phosphatase - PAP).
Which enzyme is highly specific for bile duct obstruction?
GGT.
What enzyme is used in the Guthrie test for newborn screening?
Phenylalanine hydroxylase (PKU test).
What is the best single enzyme test for liver disease?
ALT.
A patient with muscle weakness and myalgia has elevated CK. What is the likely diagnosis?
Muscle disease (e.g., myositis, rhabdomyolysis).
A patient with fever and jaundice has ALT & AST > 1000 IU/L. What is the likely cause?
Acute viral hepatitis.
A patient has high CK, dark urine, and muscle pain. What is the most likely cause?
Rhabdomyolysis.
What enzyme is best for detecting obstructive jaundice?
GGT & ALP.
A patient with high ALP but normal GGT likely has what condition?
Bone disease.
