EXAM 4 - Introduction to Clinical Chemistry

Question 1

Define clinical chemistry.

Answer 1

Qualitative (what?) and quantitative (how?) analysis of the components found in the bodily fluids
* blood and urine

In vitro analysis of biomarkers in blood and urine

Question 2

Define clinical chemistry.

Answer 2

Qualitative (what?) and quantitative (how?) analysis of the components found in the bodily fluids
* blood and urine

Question 3

Explain the significance of studying clinical chemistry.

Answer 3

Monitor changes to:
* diagnose a disease
* measure patient response to drug therapy
* analyze toxicities in clinical trials (during drug development)
* predict disease onset (ex: high glucose in blood –> diabetic/pre-diabetic

Question 4

Define biomarkers.

Answer 4

Any substance that can be used as an indicator of a biological state.
* ex: glucose, ions, proteins, hormones, lipids, metabolites, genes

Question 5

Describe the purpose of disease-related biomarkers.

Answer 5

• Identify threat of potential disease (indicator or predictor genes –> indicates potential development of disease)
• Identify present disease state (diagnostic)
• Development and progression of disease (prognostic)

Question 6

Explain the mechanism of glucose and glucose meters.

Answer 6

Glucose meters use electrochemistry to quantify glucose.
* glucose –> gluconic acid = produces H2O2
* H2O2 is used to convert ferricyanide to ferrocyanide (reversible reaction)
* ferrocyanide –> ferricyanide = produces measurable electric current

Question 7

Describe the electrolyte profile.

Answer 7

Common test to determine concentrations of Na+, K+, Cl-, and HCO3-
* measured with Ion Selective Electrodes (pH meter)

Question 8

What are Ion Selective Electrodes used for?

Answer 8

To determine how many electrodes are present.
* ex. you can use a Na+-selective pH meter to measure the amount of Na+ present.

Question 9

Acid-base homeostasis (blood pH) is intimately controlled by levels of ___.

Answer 9

circulating oxygen and carbon dioxide.

Question 10

What is the dynamic equillibrium that maintains acid-base homeostasis in the blood?

Answer 10

CO2 + H2O <-> H2CO3 <-> HCO3- + H+

Question 11

What is the difference between metabolic and respiratory acidosis/alkalosis?

Answer 11

Respiratory - effects levels of CO2
Metabolic - effects levels of HCO3-

Question 12

What is the difference between metabolic and respiratory acidosis/alkalosis?

Answer 12

Respiratory - effects levels of CO2
Metabolic - effects levels of HCO3-

Question 13

Explain what is expected with respiratory acidosis.

Answer 13

Impaired CO2 elimination from the lungs.
* increase of CO2
* pushes equation to the right
* more protons produced to balance equation
* result: acidic

Question 14

Explain what is expected with respiratory alkalosis.

Answer 14

Increased rate of respiration (elimination of CO2)
* less CO2 –> less H+ protons
* result: alkalosis (basic)

Question 15

Explain what is expected with metabolic acidosis.

Answer 15

Bicarbonate deficiency –> anion gap
* reduced acid excretion –> acid production exceeds acid elimination
* increased acids = increased H+ protons = decreased amount of bicarbonate
* result: increased anion gap (AG)

Question 16

Explain what is expected with metabolic alkalosis.

Answer 16

Excess of bicarbonate ion
* result: depletion of H+ protons

Question 17

What is the formula to calculate the anion gap?

Answer 17

AG = [NA+] - [Cl-] - [HCO3-]

Question 18

What is the ratio of cations to anions at blood’s normal charge?

Answer 18

total anion = total cation
* charge is neutral

Question 19

What anion gap value is considered normal?

Answer 19

12 nM

Question 20

What is a high anion gap predictive of?

Answer 20

Metabolic acidosis
* because HCO3- concentration is low –> when you plug into AG formula = larger number

Question 21

Describe how enzymes are used to identify which tissues/organs are damaged.

Answer 21

Enzymes are usually cystolic and membrane-bound (not found in the bloodstream)
* when cells are damaged, their membrane becomes compromised and “leaky”
* enzymes leak from the cell to the blood stream
* you can measure activity of functional enzyme and correlate to amount

Question 22

Describe what can be concluded from analysis of renal function.

Answer 22

renal function - eliminate produces of cellular metabolism
* high levels of urea or uric acid = low renal function
* creatinine clearance = GFR

Question 23

Explain the process of measuring how much creatinine is present in the plasma.

Answer 23

Jaffe Reaction
* creatinine reacts with picrate (yellow) to produce a complex structure (red)
* more creatinine = higher absorbance (more red)

Question 24

What is the purpose for measuring lipid levels?

Answer 24

High levels of lipids can be predictive or diagnostic for coronary heart disease
* measured through coupled enzyme assays

Question 25

When measuring cholesterol levels, what should you expect the output to be if there is high cholesterol? Low cholesterol?

Answer 25

High cholesterol –> increased H2O2 –> increased production of quinoneimine (red)
* @ 500nm –> higher levels of absorbance

Low cholesterol = low absorbance levels

Question 26

When measuring tryglyceride levels, what should you expect the output to be if there is high glycerol levels verus low glycerol levels?

Answer 26

glycerol –> production of H2O2 –> H2O2 is used to produce quiunoneimine (red)
* high glycerol = higher absorbance
* low glycerol = lower absorbance

Question 27

Explain the difference between LDL and HDL.

Answer 27

LDL - low density lipoprotein (“bad cholesterol”)
HDL - high density lipoprotein (“good cholesterol”)

Question 28

Describe the process of determining HDL and LDL in blood sample.

Answer 28

HDL and LDL can be seperated from blood sample by chemical precipitation or centrifugation.
* once seperated LDL and HDL fractions are seperated and total cholesterol is measured through one of the coupled-enzyme assays

Question 29

Explain what therapeutic drug monitoring is and what it is for.

Answer 29

Special branch of clinical chemistry that measures medication concentrations in the blood.

Why?
drugs with narrow therapeutic window
* each patient is different –> is therapeutic window maintained at all times?

drugs taken over an extended period of time
* change dose as needed
* monitor compliance –> make sure the patient is taking the drug (is it in the bloodstream?)

Question 30

Answer 30