Clinical Biochemistry Flashcards
What is hyperglycemia and what causes it?
Fasting blood glucose is greater than or equal to 7 mmol/L
Causes:
Insuffient insulin action - diabetes
Metabolism under acute stress (transient hyperglycemia)
What is fasting hypoglycemia? What are its symptoms?
Blood glucose below 3.5 mmol/L
Symptoms are sweating, tremor, nausea, coma, death
What causes fasting hypoglycemia?
Insulinoma - insulin producing beta cell tumors of the pancreas
What is an example of reactive hypoglycemia?
Response to stimulus
Insulin-induced - Type 1 Diabetes
What causes neonatal hypoglycemia?
Inborn errors of metabolism
What is creatinine and what is it a marker for?
Waste product of muscle creatine - depends on person’s skeletal mass
Creatinine release into blood is at constant rate.
Specific marker for kidney disease
What occurs with creatinine during kidney dysfunction?
Serum creatinine increases during kidney dysfunction because it is unable to excrete.
Creatinine in urine decreases during kidney dysfunction and can be measured by creatinine clearance test
What is a BUN and what does it reflect?
Blood Urea Nitrogen
Less specific indicator of kidney dysfunction
Reflects the balance between amino acid degradation and urea production/excretion
What occurs to BUN during kidney dysfunction and liver damage?
Serum BUN increases during kidney dysfunction
Serum BUN decreases during liver damage
What is uric acid?
Nitrogen containing waste of purine degradation
Humans cannot degrade uric acid
Hyperuricemia
Related to renal excretion problems and purine rich foods like meat, mushrooms, and spinach
What is Gout?
Formation of uric acid crystals in joints and tendons. Recurrent acute arthritis and inflammation
Ethanol intoxication, diabetic ketoacidosis, and starvation can exacerbate
What is bilirubin and the two forms?
Breakdown product of heme
Unconjugated (indirect) is bound to albumin
Conjugated (direct) with glucuronic acid is water soluble and excrete with bile
What does hyperbilirubinemia result from?
Hemolysis - unconjugated, indirect
Liver damage - unconjugated, indirect
Obstruction of the bile duct - conjugated, direct
Bilirubinuria
High direct bilirubin in the urine
Pathogical and turns the urine orange to dark amber (post hepatic jaundice)
What is albumin and its functions?
Albumin is produced by the liver and functions to transport fatty acids and bilirubin. Maintains the oncotic plasma pressure
Hypoalbuminemia
Results from liver damage, heart failure, or severe starvation
Leads to edema
Where are the different isoforms of alkaline phosphatase (AP) found?
Bones
Biliary tract
Liver
What are markers for a myocardial infarction?
Myoglobin (MG) - early marker
Creatine Kinase (CK-MB) - early marker
Cardiac Troponin - most sensitive marker, rises within hours after MI and sensitivty of troponin is 100% 12 hours after onset of symptoms
AST - mid response marker
Lactate dehydrogenase (LDH) - late response marker
What do increased serum levels of alkaline phosphatase indicate?
Obstruction of the bile duct most commonly
What is gamma-glutamyl transpeptidase a sensitive marker for?
Liver disease
High serum gamma-glutamyl transpeptidase indicates liver disease and cholestasis (reduction or stoppage of bile flow)
What are the concentration of ALT and AST in the liver and the heart and other muscles?
In liver - concentration of ALT and AST are roughly equal
In heart and other muscles - AST is much higher than ALT
What does a high serum AST and low ALT indicate?
Heart or other muscle damage
What does high serum AST and high ALT indicate?
Liver damage
