Week 4 Flashcards
Functions of plasma enzymes
Plasma enzymes have physiological functions, help diagnose inherited metabolic diseases, and are present in small amounts due to normal cell turnover.
What causes an increase in plasma enzyme activity?W
Causes include necrosis, increased cell turnover, enzyme induction due to disease or drugs, obstruction to secretion, and decreased clearance.
What factors influence reference ranges for enzyme assays?
Assay conditions (e.g., temperature, pH) and physiological factors (e.g., age, gender).
What are some clinically significant plasma enzymes?
ALP, AST, ALT, GGT, LDH, CK, α-amylase, and acid phosphatase.
What are the physiological and pathological causes of increased alkaline phosphatase (ALP)?
Physiological: Pregnancy, childhood growth.
Pathological: Cholestatic liver disease, bone diseases (Paget’s, rickets, osteomalacia), liver tumors.
What is the most sensitive and specific marker of ventricular function in heart failure?
Brain Natriuretic Peptide (BNP)
hormone secreted in response to ventricular pressure overload, making it a sensitive and specific marker for heart failure..
What are tumour markers used for?
Monitoring treatment, detecting recurrence, diagnosis, screening, and prognosis.
Name common tumour markers and their associated cancers.
PSA: Prostate cancer
AFP: Hepatocellular carcinoma, testicular cancer
β-HCG: Choriocarcinoma, testicular cancer
CEA: Colorectal, GI, lung, breast cancer
CA 19-9: Pancreatic cancer
CA 125: Ovarian cancer
CA 15-3: Breast cancer
Isoenzymes
Isoenzymes are molecular variants of an enzyme with similar catalytic activity but different chemical structures.
What does AST indicate when elevated?
> 10x ULN: Acute hepatitis, major crush injuries, severe tissue damage.
Why is ALT more liver-specific than AST?
ALT is primarily found in the liver, while AST is present in multiple tissues, including muscle and the heart.
What conditions cause an inc in GGT
Liver disease, alcohol consumption, and drug induction (e.g., phenytoin use).
Use of LDH
As a marker for muscle damage, liver and kidney damage, and lymphoma prognosis.
What conditions cause an inc in CK
Myocardial infarction, muscle trauma, surgery, prolonged exercise, diabetic ketoacidosis, acute renal failure.
Which cardiac enzymes peak first in an MI?
Myoglobin rises first, followed by CK-MB, then troponins.
Why are troponins preferred over CK-MB for MI diagnosis?
Troponins are highly specific to cardiac muscle, while CK-MB can be found in other muscle types.
What are tumour markers used for?
Diagnosis, prognosis, treatment monitoring, and detecting recurrence.
In which conditions is AFP elevated?
Hepatocellular carcinoma
Which cancers secrete β-HCG?
Choriocarcinoma and some testicular teratomas.
Why is CEA not useful for cancer screening?
CEA can also be elevated in benign conditions like liver disease and pancreatitis.
What are some key carbohydrate antigen tumour markers?
CA 19-9: Pancreatic cancer.
CA 50: Colorectal cancer.
CA 15-3: Breast cancer (prognostic).
CA 125: Ovarian cancer (monitoring response to treatment).
How is CA 125 detected in ovarian cancer?
The OC-125 antibody detects a mucin-like glycoprotein present in ovarian cancer tissues.
