L35: Clinical Biochemistry

Question 1

Name factors that cause abnormal ECF osmolality and the ion that is best indicative of the serum oncotic pressure

Answer 1

• Sodium, chloride, glucose

Question 2

Contrast the two conditions that elevate serum alkaline phosphatase concentration: liver and bone disease

Answer 2

• Both liver and bone disease will show increased levels of alk phos
• Elevated bilirubin concentration will make call of liver disease

Question 3

Explain the possible reasons for and consequences of abnormal serum potassium concentrations

Answer 3

• Potassium loss (GI, renal issue) = low values

- Renal insufficiency = high values = hyperkalemia = cardiac arrest

Question 4

Explain the importance of monitoring serum phosphate levels in a patient with DKA

Answer 4

• Low phosphate concentration impairs glucose metabolism. Think about ez phosphorylation

Question 5

Explain the significance of high serum BUN/creatinine levels

Answer 5

• BUN: reflects balance between AA degradation and urea production/excretion. BUN rises after protein-rich meal, may indicate impaired renal excretion
• Creatinine is a measure of kidney function. Increase indicates a problem with glomerular filtration, insensitive marker for kidney disease

Question 6

Explain the significance of elevated serum and urine bilirubin concentrations

Answer 6

• Elevated serum bilirubin: liver failure

- Elevated urine bilirubin: biliary obstruction

Question 7

Explain the significance and possible causes of abnormal serum albumin concentrations

Answer 7

• Maintains oncotic pressure
• Low levels cause edema
• Most common cause of hypoalbuminemia = liver disease

Question 8

Explain the significance of CRP levels

Answer 8

• Secreted by liver and is marker for acute metabolic response to injury. Rises 6 hours after injury, peak at 48 hours then decay
• Sudden rises in CRP indicate complications in healing

Question 9

Name the serum markers of MI and describe the timing of their release
In order of detection:

Answer 9

• Troponins- TnC: most sensitive, detected as early as 12 hours after an MI
• CK-MB
• AST
• LDH: several days after

Question 10

Explain why it is important to determine the relative concentrations of ALT and AST aminotransferases

Answer 10

• Muscle: AST = 10 x higher than ALT
• Liver: equal concentrations of ALT:AST
• Muscle damage indicated by high AST:low ALT
• Liver damage indicated by high AST:high ALT (look at bilirubin to confirm)

Question 11

Name the 4 most important tests conducted during a urine analysis

Answer 11

• Glucose: indicates hyperglycemia
• Bilirubin (conjugated): indicates biliary obstruction
• Ketones: uncontrolled diabetes or starvation
• Protein: glomerular damage (if not from leukocytes or RBCs)

Question 12

Describe kidney and liver function tests

Answer 12

• LFTs: bilirubin, ALT/AST, alk phosp
  Bilirubin, alk phos: elevated = blockage of bile duct
  ALT and AST: elevated = hepatocellular damage
• Kidney: BUN, creatinine, Na, K, bicarb, Urine osmolality
  BUN/Creat = elevated in renal failure
  Urine osmolality = low in renal failure pts

Question 13

Explain the purpose of the BMP

Answer 13

• gives comprehensive info about kidney function, blood sugar, electrolyte and acid/base balance

Question 14

Name the tests that are commonly used to monitor a diabetic patient

Answer 14

• HbA1C
• Proteinuria
• C-peptide in serum

Question 15

Function of albumin

Answer 15

• Binding hydrophobic molecules: steroids, FAs, unconjugated bilirubin
• Binding calcium
• Maintenance of oncotic pressure

Question 16

What are possible causes of high / low serum calcium levels:

Answer 16

• Low calcium = hormonal disturbances
• High calcium = hormonal disturbances too, but signifies degradation of calcium stores in skeleton through bone dz or bone cancer

Question 17

What does high / low sodium values indicate?

Answer 17

• High = dehydration

- Low = water retention