EXAM 4 - Introduction to Clinical Chemistry Flashcards
Define clinical chemistry.
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
Define clinical chemistry.
Qualitative (what?) and quantitative (how?) analysis of the components found in the bodily fluids
* blood and urine
Explain the significance of studying clinical chemistry.
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
Define biomarkers.
Any substance that can be used as an indicator of a biological state.
* ex: glucose, ions, proteins, hormones, lipids, metabolites, genes
Describe the purpose of disease-related biomarkers.
- 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)
Explain the mechanism of glucose and glucose meters.
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
Describe the electrolyte profile.
Common test to determine concentrations of Na+, K+, Cl-, and HCO3-
* measured with Ion Selective Electrodes (pH meter)
What are Ion Selective Electrodes used for?
To determine how many electrodes are present.
* ex. you can use a Na+-selective pH meter to measure the amount of Na+ present.
Acid-base homeostasis (blood pH) is intimately controlled by levels of ___.
circulating oxygen and carbon dioxide.
What is the dynamic equillibrium that maintains acid-base homeostasis in the blood?
CO2 + H2O <-> H2CO3 <-> HCO3- + H+
What is the difference between metabolic and respiratory acidosis/alkalosis?
Respiratory - effects levels of CO2
Metabolic - effects levels of HCO3-
What is the difference between metabolic and respiratory acidosis/alkalosis?
Respiratory - effects levels of CO2
Metabolic - effects levels of HCO3-
Explain what is expected with respiratory acidosis.
Impaired CO2 elimination from the lungs.
* increase of CO2
* pushes equation to the right
* more protons produced to balance equation
* result: acidic
Explain what is expected with respiratory alkalosis.
Increased rate of respiration (elimination of CO2)
* less CO2 –> less H+ protons
* result: alkalosis (basic)
Explain what is expected with metabolic acidosis.
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)
Explain what is expected with metabolic alkalosis.
Excess of bicarbonate ion
* result: depletion of H+ protons
What is the formula to calculate the anion gap?
AG = [NA+] - [Cl-] - [HCO3-]
What is the ratio of cations to anions at blood’s normal charge?
total anion = total cation
* charge is neutral
What anion gap value is considered normal?
12 nM
What is a high anion gap predictive of?
Metabolic acidosis
* because HCO3- concentration is low –> when you plug into AG formula = larger number
Describe how enzymes are used to identify which tissues/organs are damaged.
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
Describe what can be concluded from analysis of renal function.
renal function - eliminate produces of cellular metabolism
* high levels of urea or uric acid = low renal function
* creatinine clearance = GFR
Explain the process of measuring how much creatinine is present in the plasma.
Jaffe Reaction
* creatinine reacts with picrate (yellow) to produce a complex structure (red)
* more creatinine = higher absorbance (more red)
What is the purpose for measuring lipid levels?
High levels of lipids can be predictive or diagnostic for coronary heart disease
* measured through coupled enzyme assays
When measuring cholesterol levels, what should you expect the output to be if there is high cholesterol? Low cholesterol?
High cholesterol –> increased H2O2 –> increased production of quinoneimine (red)
* @ 500nm –> higher levels of absorbance
Low cholesterol = low absorbance levels
When measuring tryglyceride levels, what should you expect the output to be if there is high glycerol levels verus low glycerol levels?
glycerol –> production of H2O2 –> H2O2 is used to produce quiunoneimine (red)
* high glycerol = higher absorbance
* low glycerol = lower absorbance
Explain the difference between LDL and HDL.
LDL - low density lipoprotein (“bad cholesterol”)
HDL - high density lipoprotein (“good cholesterol”)
Describe the process of determining HDL and LDL in blood sample.
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
Explain what therapeutic drug monitoring is and what it is for.
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?)
