Final Exam Study Guide
Unit 1: Unit Conversions and Calculations
A. SI Unit Conversions (U1L1-O1)
Key Concept:
International System of Units (SI) is the standard measurement system in science.
Importance of understanding prefixes and corresponding powers of ten for accurate unit conversions.
Review Topics:
Common SI base units: meter, gram, liter.
Common SI prefixes: kilo (10^3), milli (10^-3), micro (10^-6), nano (10^-9), pico (10^-12).
Conversion techniques: dimensional analysis or conversion factors.
Self-Assessment Questions:
What is the SI base unit for mass and volume?
What does "milli" represent in powers of ten?
Steps for converting micrograms to kilograms.
B. Primary Standard Reference Materials (U1L1-O2)
Key Concept:
Primary standard reference materials are highly purified substances with known compositions used for solution standardization and instrument calibration.
Review Topics:
Definition of standard solution and its importance.
Characteristics of primary standards: high purity, stability, known composition, high molecular weight.
Differences between primary and secondary reference materials.
Organizations certifying primary standards (e.g., NIST).
Role of primary standards in lab calibration and quality control.
Self-Assessment Questions:
Why is high purity essential for a primary standard?
Difference between a primary standard and a routine assay reagent.
Example of a primary standard in acid-base titrations.
C. Dilution Calculations (U1L1-O3)
Key Concept:
Dilution reduces the concentration of a solution by adding solvent. Important for reagent preparation and accurate patient reporting.
Review Topics:
Dilution factor understanding and calculation.
Use of formula M1V1 = M2V2 for molarity-based dilutions.
Calculating volumes for stock solutions and final concentrations.
Determining original concentrations after dilution.
Self-Assessment Questions:
What does a "1:10 dilution" mean?
Concentration of a diluted solution from a 5 M solution diluted to 100 mL?
Find undiluted sample concentration from a 1:5 dilution yielding a result of 20 mg/dL.
D. Concentration Calculations (U1L1-O4)
Key Concept:
Clinical chemistry requires accurate concentration calculations in different units (molarity, percentage).
Review Topics:
Definition and calculation of molarity (M).
Understanding percentage concentrations (w/v, v/v, w/w).
Serial dilution calculations.
Converting concentrations (requires molar mass knowledge).
Self-Assessment Questions:
How to calculate molarity with known solute mass and solution volume?
Difference between 10% (w/v) and 10% (v/v)?
Performing two-fold serial dilution.
E. Laboratory Glassware (U1L1-O5)
Key Concept:
Laboratory glassware types are designed for specific purposes to ensure accuracy and precision in volume measurement.
Review Topics:
Common laboratory glassware: beakers, graduated cylinders, volumetric flasks, burettes, pipettes.
Intended use and accuracy/precision levels of each type.
Differences between holding/mixing glassware and accurate volume measurement glassware.
When to use volumetric glassware.
Self-Assessment Questions:
Which glassware for precise standard solution preparation? Why?
When is a graduated cylinder suitable for measuring liquid volume?
Purpose of a burette.
F. Clinical Chemistry Lab Equipment (U1L1-O6)
Key Concept:
Understanding the principles of operation, usage, and maintenance of lab instruments is crucial for accuracy.
Review Topics:
Basic principles and uses of clinical chemistry equipment: centrifuges, spectrophotometers, electronic balances, pipettes, water purification systems, pH meters.
Differences between swinging-bucket and fixed-angle centrifuges.
Steps for proper equipment use, maintenance, and cleaning.
Self-Assessment Questions:
Purpose of balancing a centrifuge? Consequences of imbalance?
Cuvette handling for accurate spectrophotometric readings?
Importance of electronic balance calibration?
G. Clinical Chemistry Samples (U1L1-O7)
Key Concept:
Understanding sample types and factors affecting their integrity is essential for accurate test results.
Review Topics:
Common clinical chemistry sample types: blood (serum, plasma, whole blood), urine, cerebrospinal fluid.
Key differences between serum and plasma.
Proper collection, handling, and storage for each sample type.
Causes and effects of pre-analytical errors (e.g., hemolysis, lipemia, icterus).
Self-Assessment Questions:
Typical anticoagulant for plasma samples?
Visual characteristic of hemolyzed blood samples? Effects on potassium results?
Meaning of turbid serum appearance?
II. Quality Control and Assurance
A. Quality Control and Assurance Terms (U1L2O1)
Key Concept:
QC and QA ensure accuracy, reliability, and consistency of test results in the lab. Understanding QC and QA terms is fundamental.
Review Topics:
Definitions and differences between QC and QA.
Accuracy, precision, analytical sensitivity, analytical specificity explained.
Random error vs systematic error with examples.
Definitions of reference range, analytical measurement range (AMR), clinically reportable range (CRR), and limit of detection (LOD).
Purpose of confidence intervals and medical decision levels.
Linearity and descriptive statistics in lab testing.
Self-Assessment Questions:
Difference between accuracy and precision?
Example of systematic error in a lab?
Clinical significance of the clinically reportable range?
B. Mean, Standard Deviation, and Coefficient of Variation (U1L2O2)
Key Concept:
Basic statistical concepts for evaluating data central tendency and variability are essential for QC.
Review Topics:
Definition and calculation of mean (average).
Significance of standard deviation as a measure of dispersion.
Coefficient of variation (CV) and its usefulness for comparing data variability.
Interpretation of large vs small standard deviation or CV.
Self-Assessment Questions:
Mean calculation?
High standard deviation significance?
CV usefulness for comparing assay precision?
C. Westgard Rules (U1L2O3)
Key Concept:
Westgard Rules are statistical criteria for evaluating quality control data acceptability.
Review Topics:
Common Westgard Rules: 1-2s, 1-3s, 2-2s, R4s, 4-1s, 10x explained.
Type of errors (random/systematic) indicated by each rule violation.
Actions upon Westgard Rule violations (e.g., no action, warning rule).
Advantages of using a multi-rule QC plan.
Self-Assessment Questions:
What does a "1-3s" violation indicate? Actions?
2-2s rule significance?
Purpose of warning rules in the Westgard system?
D. Quality Control Ranges and Confidence Intervals (U1L2O6)
Key Concept:
QC ranges are based on expected assay variability. Confidence intervals give statistical estimates for mean ranges.
Review Topics:
Determining QC ranges (mean ± 2 or 3 standard deviations).
Definition of confidence interval and its relationship to standard deviation.
Calculation of QC ranges using mean and standard deviation.
Confidence intervals for assessing QC result acceptability.
Self-Assessment Questions:
Given mean of 100 and standard deviation of 2, what is 2 SD QC range?
Definition of 95% confidence interval?
E. Patient Results and Test System Accuracy (U1L2O7)
Key Concept:
Reviewing patient results can signal test system accuracy and potential analytical errors.
Review Topics:
Concept of delta checks: current vs previous patient results.
Unexpected results indicating potential test system problems (calibration, reagent issues).
Importance of correlating patient results with clinical data.
Patient result reviews in overall quality assurance.
Self-Assessment Questions:
What is a delta check, and why use it?
Reasons to investigate significantly different glucose results?
Reviewing related tests for accuracy assessment?
III. Amino Acid Structure and Properties
Fundamental structure of an amino acid: Contains an amino group and a carboxyl group.
Influence of the R group on amino acid properties and behavior in biological systems.
IV. Ammonia Specimen Collection and Handling
Importance of keeping ammonia specimens on ice and prompt processing for accuracy.
Recommended blood collection tube and significance of anticoagulant choice.
V. Carbohydrate Chemistry Basics
Differentiate between monosaccharide (glucose), disaccharide (sucrose), and polysaccharide (glycogen).
Glycosidic bond links monosaccharides in larger structures.
VI. Clinical Enzymology: Diagnostic Markers
Serum enzymes (AST, ALT) are vital for liver disease diagnosis.
Amylase and lipase levels serve as key indicators for pancreatitis.
VII. Coronary Risk Factors and Atherosclerosis
HDL vs LDL cholesterol levels correlate with coronary heart disease risk.
Define metabolic syndrome as a risk factor for atherosclerotic disease.
VIII. Creatinine Clearance Calculation Problems
Understand creatinine clearance as a kidney function measure.
Timed urine collection is necessary for accurate calculation.
IX. Diabetes Mellitus Fundamentals
Key distinctions between type 1 and type 2 diabetes.
Three criteria for diabetes diagnosis: fasting plasma glucose, oral glucose tolerance test, A1C.
X. Enzyme Classes and Functions
Function of hydrolases (e.g., catalyze hydrolysis reactions).
Ligases join substrates using energy from ATP.
XI. Enzyme Kinetics
Zero-order vs first-order kinetics based on substrate concentration effects.
Zero-order kinetics occur when enzymes are saturated.
XII. Enzyme Factors and Activity
Major factors influencing enzyme-catalyzed reactions: temperature, pH, substrate concentration.
Competitive inhibitors bind to the active site, blocking substrate access.
XIII. Enzyme Structure
Primary structure defined by amino acid sequences.
The active site is crucial for substrate binding and catalysis.
XIV. Glucose Metabolism
Differences among glycogenesis, glycogenolysis, and gluconeogenesis.
Increased serum acetone indicates ketosis or uncontrolled diabetes.
XV. HbA1c and Long-Term Glucose Control
HbA1c indicates long-term glucose levels over 3 months.
Recent behaviors can affect HbA1c readings prior to medical appointments.
XVI. Hormones and Blood Glucose
Insulin is the primary hormone reducing blood glucose levels.
Glucagon and epinephrine stimulate glycogenolysis, raising glucose levels.
XVII. Key Clinical Proteins
Transferrin transports iron.
C-reactive protein measures inflammation.
XVIII. Lipid Panel Interpretation
Increased triglycerides cause hazy serum appearance.
Fasting before lipid tests is essential for accurate results.
XIX. Lipid Profile Calculation
Friedewald formula estimates LDL using total cholesterol and HDL, triglycerides.
Unreliable LDL estimation occurs if triglycerides are elevated (>400 mg/dL).
XX. Lipids and Fatty Acids
Saturated vs polyunsaturated fatty acids: saturated have no double bonds.
Lipid storage occurs mainly as triglycerides in adipose tissue.
XXI. Lipoprotein Metabolism
Chylomicrons transport dietary fat from intestines to tissues.
HDL functions to transport cholesterol for excretion.
XXII. Metabolism Inborn Errors and Hypoglycemia
Galactosemia caused by a defect in galactose metabolism.
Clinical triad for diagnosing hypoglycemia includes tremors, sweating, confusion.
XXIII. Nitrogen Metabolism Products
Major nitrogenous waste in protein metabolism: urea.
Nonprotein nitrogen compounds include creatinine, ammonia, uric acid.
XXIV. Nonprotein Nitrogen Compounds and Kidney Function
Urea used to assess kidney function due to its blood concentration.
Urea is synthesized in the liver from ammonia and carbon dioxide.
XXV. Plasma Glucose Analysis
Sodium fluoride prevents glycolysis in plasma glucose samples.
Glucose stability decreases if blood samples are left at room temperature.
XXVI. Plasma Levels and Pathology
Elevated urea and creatinine associated with kidney dysfunction.
Elevated uric acid linked to gout or other conditions.
XXVII. Protein Structure and Function
Primary structure maintained by peptide bonds; secondary structure by hydrogen bonds.
Diverse functions: enzymes, transport proteins, antibodies.
XXVIII. Protein Synthesis and Metabolism
Liver is the primary organ for protein synthesis.
Deamination is crucial for amino acid catabolism.
XXIX. Renal Azotemia Causes
Identify prerenal, renal, and postrenal azotemia causes.
Intrinsic kidney disease directly relates to renal azotemia.
XXX. Routine Lipid Profile Interpretation
Key components: total cholesterol, LDL, HDL, triglycerides.
Fasting is important because it influences lipid concentration.
XXXI. Serum Albumin Concentration
Increased in dehydration; decreased in liver disease and nephrotic syndrome.
Unit 3: Electrolyte Physiology (U3L1O1 & U3L1O2)
A. Sodium (Na+)
Primary Role:
Maintains water distribution and osmotic pressure; essential for nerve function and muscle contraction.
Regulation:
Controlled by the renin-angiotensin-aldosterone system (RAAS) and ADH affecting sodium levels.
Imbalances:
Hyponatremia: Low sodium, can lead to cellular swelling and altered CNS function.
Hypernatremia: High sodium, typically from water loss; can lead to cellular dehydration.
B. Potassium (K+)
Primary Role:
Major intracellular cation for cardiac and neuromuscular functions.
Regulation:
Controlled primarily by kidney excretion, influenced by aldosterone and insulin.
Imbalances:
Hypokalemia: Low potassium causes cardiac arrhythmias and muscle weakness.
Hyperkalemia: High potassium risks cardiac arrest and is often seen in renal failure.
C. Chloride (Cl-)
Primary Role:
Helps maintain osmotic balance; vital for acid-base homeostasis via chloride shift.
Regulation:
Regulated indirectly through sodium levels.
Imbalances:
Hypochloremia: Low chloride associated with metabolic alkalosis.
Hyperchloremia: High chloride linked to metabolic acidosis.
D. Bicarbonate (HCO3-)
Primary Role:
Buffering acid in the blood; maintains pH balance.
Regulation:
Controlled by renal excretion and reabsorption.
Imbalances:
Decreased Bicarbonate: In metabolic acidosis.
Increased Bicarbonate: Indicates metabolic alkalosis.
E. Calcium (Ca2+)
Primary Role:
Vital for muscle contraction, blood clotting, and bone structure.
Regulation:
Controlled by PTH, vitamin D, and calcitonin.
Imbalances:
Hypocalcemia: Low levels can cause neuromuscular excitability.
Hypercalcemia: High levels commonly seen in malignancies; causes lethargy.
F. Magnesium (Mg2+)
Primary Role:
Co-factor in enzymatic reactions and energy production.
Regulation:
Regulated by renal mechanisms.
Imbalances:
Hypomagnesemia: Causes cramps and arrhythmias.
Hypermagnesemia: Leads to hypotension and respiratory depression.
G. Phosphate (PO43-)
Primary Role:
Crucial in energy metabolism and bone health.
Regulation:
Regulated by PTH and renal processes.
Imbalances:
Hypophosphatemia: Can occur due to malabsorption or renal excretion.
Hyperphosphatemia: Often associated with renal disease.
H. Lactate
Physiology:
Byproduct of anaerobic metabolism; can be converted back to glucose.
Elevated Levels:
Associated with hypoxia, strenuous exercise, and sepsis.
II. Acid-Base Balance (U3L2O1, U3L2O6, U3L2O7)
A. Buffer Systems
Bicarbonate Buffer System:
Primary blood buffer.
Reaction: CO2 + H2O ⇌ H2CO3 ⇌ H+ + HCO3-.
Phosphate Buffer System:
Important in urine and intracellular fluid buffering.
Protein Buffer System:
Proteins like hemoglobin and albumin buffer due to their charge properties.
B. pH Regulation
Respiratory Regulation:
Adjusts blood pH by CO2 retention/excretion via breathing.
Renal Regulation:
Slow but effective in controlling bicarbonate and H+ ion balance.
C. pH-Hydrogen Ion Relationship
pH is the negative log of [H+].
Inverse relationship: Higher [H+] leads to lower pH (more acidity).
D. Gas Transport
Oxygen Transport:
Mostly bound to hemoglobin; diffuses into tissues.
Carbon Dioxide Transport:
Mainly as bicarbonate; some bound to hemoglobin.
III. Acid-Base Imbalance States (U3L2O3)
A. Metabolic Acidosis
Cause:
Bicarbonate deficit or excess non-volatile acids.
Characteristics:
Decreased pH and HCO3-.
Common Causes:
Diabetic ketoacidosis, lactic acidosis, diarrhea.
Compensation:
Hyperventilation for pH correction.
B. Metabolic Alkalosis
Cause:
Bicarbonate excess or loss of acids.
Characteristics:
Increased pH and HCO3-.
Common Causes:
Vomiting, diuretics.
Compensation:
Hypoventilation to raise CO2 levels.
C. Respiratory Acidosis
Cause:
CO2 retention from hypoventilation.
Characteristics:
Decreased pH and increased PaCO2.
Common Causes:
Respiratory failure from COPD, overdose.
Compensation:
Renal adjustment of bicarbonate.
D. Respiratory Alkalosis
Cause:
Decreased CO2 from hyperventilation.
Characteristics:
Increased pH and decreased PaCO2.
Common Causes:
Anxiety, fever, hypoxia.
Compensation:
Renal excretion of bicarbonate.
IV. Compensation Mechanisms (U3L2O5)
Compensation in metabolic and respiratory imbalances involves secondary systems to restore pH.
Metabolic Acidosis: Respiratory compensation through hyperventilation.
Metabolic Alkalosis: Respiratory compensation through hypoventilation.
Respiratory Acidosis: Renal compensation via increased bicarbonate reabsorption.
Respiratory Alkalosis: Renal compensation with bicarbonate excretion.
Compensation may be partial or complete based on pH restoration.
V. Anion Gap (U3L1O3, U3L1O4AG)
Calculation: Anion Gap = [Na+] - [Cl-] - [HCO3-]
Normal Range: 8-12 mEq/L.
Usefulness: Evaluates metabolic acidosis.
High Anion Gap: Indicates unmeasured anions (e.g., lactic acid).
Normal Anion Gap: Often secondary to bicarbonate loss.
VI. Osmolality and Osmol Gap (U3L1O3, U3L1O4Osm, U3L1O4OG)
Osmolality: Concentration of solutes in serum fluid.
Calculation: Serum Osmolality ≈ 2[Na+] + [Glucose]/18 + [BUN]/2.8
Clinical Usefulness: Assessing dehydration or solute concentration.
Osmol Gap: Difference between measured and calculated osmolality; important for detecting unmeasured substances.
VII. Henderson-Hasselbalch Equation (U3L2O2)
Equation: pH = pKa + log ([HCO3-]/[H2CO3])
Usefulness: Describes pH dynamics in buffer systems.
VIII. Electrolyte Concentration Assessment Techniques (U3L1O5)
A. Ion-Selective Electrodes (ISE)
Principle: ISEs use selective membranes that respond to specific ions generating measurable potentials.
Advantages: Rapid and direct measurements of electrolytes in fluids.
Types:
Direct ISE: measures in whole blood.
Indirect ISE: dilution-based measurements in serum or plasma.