Chemical Pathology 2 Flashcards
1
Q
Albumin - Definition and Role
A
Major plasma protein synthesised in the liver. Contributes to oncotic pressure so low levels result in oedema.
2
Q
Causes of Low Albumin
A
- Decreased synthesis - malnutrition, malabsorption or in chronic liver disease.
- Abnormal distribution - enters interstitial space if increased vascular permeability e.g. sepsis.
- Excess excretion - nephrotic syndrome, protein losing enteropathy, burns or haemorrhage.
3
Q
Creatinine Kinase
A
- 3 forms - CK-MM in skeletal muscle, CK-BB in brain and CK-MB in cardiac muscle.
- No longer routinely used to detect MI.
- Raised CK - statin related myopathy, muscle damage from any cause e.g. strenuous exercise, myopathy e.g. muscular dystrophy or can be physiological in Afro-Caribbean’s.
4
Q
Alkaline phosphatase
A
- Present in liver, bone, intestine and placenta but pathological rises usually due to liver or bone disease.
- Causes of raised ALP (<5 times normal) - fracture, tumour, osteomyelitis or hepatitis.
- Causes of raised ALP (>5 times normal) - physiological in 3rd trimester or during a growth spurt, Pagets, osteomalacia, cholestasis or cirrhosis.
5
Q
Troponin
A
- A structural protein complex (troponin I, T and C) in the actin-myosin contractile apparatus.
- Troponin I and T measured in suspected MI.
- Levels rise at 4-6 hours post MI.
- Levels peak at 12-24 hours.
- Levels remain raised for 3-10 days.
6
Q
LFTs - Obstructive Picture
A
Raised serum bilirubin and ALP
7
Q
Bilirubin
A
- Derived from haem in red blood cells.
- Transported almost completely bound to albumin.
- Taken up by the liver and conjugated to form mono and di-glucuronides.
- Conjugated bilirubin is broken down by bacteria to form stercobilinogens - excreted in faeces.
- Also enters enterohepatic circulation and is excreted as urobilinogen in urine.
8
Q
LFTs - Acute Hepatocellular Damage
A
- Raised serum aminotransferase activity - AST and ALT are non-specific indicators of acute damage to hepatocytes.
- Causes - hepatitis, toxic injury, drug overdose, hypoxia or secondary to right heart failure.
9
Q
LFTs - Chronic Liver Disease
A
Serum albumin concentration and prothrombin time can be used to measure synthetic capacity.
10
Q
Gamma-glutamyl Transpeptidase
A
A microsomal enzyme that is raised with cholestasis, acute hepatocellular damage and ingestion of alcohol and some drugs e.g. phenytoin.
11
Q
Alpha-fetoprotein
A
- Synthesised by the fetal liver and present in low concentrations in healthy adults.
- Increases by 80-90% in hepatocellular carcinoma.
12
Q
Causes of Jaundice
A
- Pre-hepatic - haemolysis.
- Hepatic - viral hepatitis, drugs, alcoholic hepatitis, cirrhosis, pregnancy and cholestasis.
- Post-hepatic - common bile duct stones, malignancy e.g. bile duct, head of pancreas, biliary stricture, sclerosing cholangitis or pancreatic pseudocyst.
13
Q
Insulin - Definition
A
- A protein synthesised in Beta cells in the islets of Langerhans in the pancreas.
- Main targets - liver, muscle and adipose tissue.
14
Q
Insulin - Actions
A
- Lower blood glucose levels
- Promotes - glucose uptake in muscle and adipose tissue, glycolysis (glucose degradation), glycogen synthesis, protein synthesis and the uptake of potassium and phosphate.
- Inhibits - gluconeogenesis, glycogenolysis, lipolysis, ketogenesis and proteolysis.
15
Q
Calcium Homeostasis
A
- Parathyroid hormone is released in response to low levels of circulating unbound calcium.
- PTH causes bone reabsorption.
- PTH causes increased renal Ca reabsorption.
- PTH causes hydroxylation of vitamin D in the liver and kidneys which leads to production of 1,25-DHCC which promotes intestinal reabsorption of Calcium.
