What prolonged treatment can borosilicate glass tolerate?
Prolonged heating and sterilization.
How do volumetric transfer pipettes differ from graduated pipettes?
Transfer pipettes have one calibration mark; graduated pipettes have subdivisions for measuring and delivering fractions of their capacity.
How does an air-displacement micropipette separate its piston from the sample?
With an air cushion.
What samples are positive-displacement micropipettes recommended for?
Viscous, dense, or problematic samples.
Which reagents suit most analytical procedures, and which are used for maximum purity?
ACS analytical-grade reagents suit most procedures; ultrapure spectrograde or nanograde reagents minimize interference.
Which reagent water type is purest and used for high-accuracy standards?
Type I reagent water.
What is Type II reagent water suited for?
Most laboratory procedures.
How should a body-fluid spill be disinfected, and for how long?
Apply 5.25% sodium hypochlorite or 10% bleach diluted 1:10 for at least 20 minutes.
Which hazards do Class II biological safety cabinets protect against?
They protect both the worker and the work using two HEPA filters.
How are Class III biological safety cabinets constructed for hazardous organisms?
They are gas-tight, negative-pressure enclosures with glove ports.
How is molarity calculated from solute concentration in g/L and molecular weight?
How is equivalent weight calculated from molecular weight and valence?
How are the quantities in diluted-solution calculations related?
How do you convert a conventional unit to an SI unit?
Multiply by the listed conversion factor.
How do you convert an SI unit to a conventional unit?
Divide by the listed conversion factor.
How is the coefficient of variation calculated?
What does a lower coefficient of variation indicate?
Greater precision.
What percentages of normally distributed observations fall within one, two, and three standard deviations?
Approximately 68%, 95%, and 99%, respectively.
What does accuracy describe in measurement?
Closeness to the true value.
What does precision describe in measurement?
The ability to produce results that agree closely with one another.
What does random error affect unpredictably?
Precision.
What pattern defines a shift in control values?
An abrupt change that remains on one side of the mean for six consecutive days.
How long should a tourniquet remain applied during blood collection?
Less than one minute.
What is the evacuated-tube order of draw?
Sterile culture, light blue, red, serum separator, plasma separator, green, lavender, then gray.
Which analytes may hemolysis increase?
Potassium, magnesium, phosphate, iron, LD, AST, ALT, ALP, and CK.
Which measurements can hemolysis decrease?
Lipase and glucose measured by hexokinase.
What does the Beer-Lambert law state about absorbance?
Absorbance is directly proportional to concentration and path length.
What does a blank do in spectrophotometry?
It subtracts non-analyte absorbance and sets zero absorbance.
What distinguishes a standard from a control in spectrophotometry?
A standard has known purity and concentration for calibration or quantitation; a control has target values for monitoring assay performance.
What distinguishes turbidimetry from nephelometry?
Turbidimetry measures blocked light; nephelometry measures scattered light.
How is diagnostic sensitivity calculated?
How is diagnostic specificity calculated?
What does a positive predictive value represent?
The probability that a positive result indicates disease.
What does a negative predictive value represent?
The probability that a negative result indicates absence of disease.
How does MEIA differ from FPIA in separation and target molecular size?
MEIA requires separation and targets high-molecular-weight substances; FPIA requires no separation and targets low-molecular-weight substances.
Which mass spectrometry method is the gold standard for drug analysis?
GC-MS.
Which mass spectrometry method identifies microbes and analyzes biomolecules?
MALDI-TOF MS.
Which analysis method uses separate containers for random-access and STAT testing?
Discrete analysis.
Which pancreatic cells produce insulin, the only hypoglycemic hormone?
Pancreatic islet beta cells.
What does insulin promote in cellular glucose handling?
Glucose uptake, glycolysis, glycogenesis, and lipogenesis.
Which pancreatic cells produce glucagon, a major hyperglycemic hormone?
Pancreatic islet alpha cells.
Which glucose pathways does glucagon promote and inhibit?
It promotes gluconeogenesis and glycogenolysis and inhibits glycolysis.
What plasma glucose level defines hypoglycemia, and what is its panic value?
Below 50 mg/dL defines hypoglycemia; below 40 mg/dL is the panic value.
What three findings constitute Whipple’s triad?
Hypoglycemia symptoms, low plasma glucose, and symptom relief after glucose correction.
What causes absolute insulin deficiency in type 1 diabetes?
Autoimmune or idiopathic beta-cell destruction.
What is the core metabolic problem in type 2 diabetes?
Insulin resistance with progressive insulin deficiency.
What random plasma glucose level diagnoses diabetes when symptoms are present?
Above 200 mg/dL.
What fasting glucose range defines prediabetes?
100–125 mg/dL.
How long must fasting last before a fasting glucose test?
At least 8 hours without food.
Why are copper-reduction glucose assays nonspecific?
Any reducing agent can produce a falsely increased result.
What are the three main functions of apolipoproteins?
They provide structural support, regulate lipoprotein metabolism, and bind cell receptors.
Which apolipoprotein activates LCAT?
Apo A-I.
Which triglycerides do chylomicrons and VLDL transport, and in what proportions?
Chylomicrons transport dietary triglycerides and contain 86%; VLDL transports endogenous triglycerides and contains 55%.
Which lipoproteins and lipid elevations characterize Fredrickson types 1, 2a, 2b, 3, 4, and 5?
Type 1: chylomicrons, very high triglycerides; 2a: LDL, high cholesterol; 2b: LDL and VLDL, high cholesterol and triglycerides; 3: IDL and β-VLDL, high cholesterol and triglycerides; 4: VLDL, high triglycerides; 5: chylomicrons and VLDL, high triglycerides.
How is flint glass made, and what can its released alkali cause?
It is inexpensive soda-lime glass made from silicon, calcium, and sodium oxides; released alkali can cause errors in some determinations.
What is low-actinic glass used to contain?
Photosensitive substances.
Which instruments check centrifuge speed and temperature?
A tachometer or strobe light checks speed, and a thermometer checks temperature.
How often is centrifuge quality control performed?
Quarterly.
What are the efficiencies and particle sizes for HEPA and ULPA filters?
HEPA: 99.97% at 0.3 microns; ULPA: 99.99% at 0.12 microns.
What does a threshold limit value specify for an 8-hour shift?
The allowable exposure during an 8-hour shift.
How many control levels are analyzed in internal quality control every 24 hours?
At least two.
How is the standard deviation index (SDI) calculated?
What SDI value indicates poor performance?
Greater than 2.0.
What are the four stages of the PDCA quality cycle?
Plan, Do, Check, and Act.
Which anticoagulant chelates calcium and is used in lavender hematology and pink crossmatch tubes?
EDTA.
Which analytes can EDTA falsely increase or decrease?
It can increase sodium and potassium and decrease calcium, magnesium, iron, phosphate, CK, ALP, and amylase.
What does sodium fluoride prevent, and what test is it primarily used for?
It prevents glycolysis and is used primarily for glucose testing.
What does the modified Allen test verify before radial artery puncture?
That the ulnar artery can supply the hand.
What formula relates absorbance to percent transmittance?
How does a double-beam spectrophotometer compensate for source intensity variation?
It splits light between reference and sample cuvets.
What does fluorometry measure?
Light emitted by excited molecules.
How does fluorometry's sensitivity compare with spectrophotometry?
Fluorometry is about a thousand times more sensitive.
What does scintillation counting detect, and which detector measures the flashes?
Flashes of light detected by a photomultiplier tube.
Which labels do gamma counters detect?
Iodine-125 or iodine-131 labels.
How does continuous-flow automation move liquids?
It pumps liquids through continuous tubing.
What do air bubbles do in continuous-flow automation?
They separate and clean samples.
How does ion counting convert scintillations into measurable signals?
A photomultiplier tube detects scintillations as electrical impulses.
Which ion-counting method is used for beta counting with hydrogen-3 or carbon-14 labels?
Liquid scintillation.
Which POCT devices are most commonly used, and how often is quality control recommended?
Glucose monitors are most common, and quality control is recommended once per day of use.
What does ACTH promote in glucose metabolism?
Gluconeogenesis and glycogenolysis.
When does fasting hypoglycemia occur, and when does reactive hypoglycemia usually occur?
Fasting hypoglycemia occurs after 10 hours without food; reactive hypoglycemia usually occurs within 4 hours after a meal.
What causes diabetes besides type 1 and type 2 mechanisms?
Endocrinopathies and genetic or drug-induced causes.
Which diabetes nomenclature is no longer used?
Type I/type II and IDDM/NIDDM.
What does HbA1c reflect, and when is it unreliable?
Average glucose over 2–3 months; it is unreliable in hemolytic disorders and hemoglobinopathies.
How much lower is whole-blood glucose than plasma glucose?
10–15%.
How does capillary glucose compare with venous glucose?
It is 2–5 mg/dL higher.
How can glycolysis be limited when prompt analysis is not possible?
Use sodium fluoride or a serum separator tube.
How quickly does glucose fall at room temperature and at 4°C?
7 mg/dL/hour at room temperature and 2 mg/dL/hour at 4°C.
Which glucose form does glucose oxidase specifically act on?
β-D-glucose.
What enzyme converts α-D-glucose into β-D-glucose?
Mutarotase.
What enzyme deficiency causes galactosemia?
GALT deficiency.
Which lipids form the lipoprotein surface and hydrophobic core?
The surface contains apolipoproteins, phospholipids, and non-esterified cholesterol; the core contains triglycerides and cholesteryl esters.
What does LCAT do to cholesterol in lipoproteins?
LCAT esterifies cholesterol, removing its polarity.
How do chylomicrons, VLDL, and LDL affect plasma appearance?
Chylomicrons form a creamy layer, VLDL makes plasma turbid, and LDL does not alter plasma clarity.
What genetic defects and lipoprotein abnormalities characterize abetalipoproteinemia, hypobetalipoproteinemia, and Tangier disease?
Abetalipoproteinemia is autosomal recessive, with absent Apo B-containing lipoproteins and MTTP mutations on chromosome 4; hypobetalipoproteinemia is autosomal dominant, with Apo-B gene mutations; Tangier disease is autosomal recessive, caused by ABCA1 mutations, and lacks HDL, Apo A-I, and Apo A-II.
Answer 58 questions on Clinical Protein and Enzyme Analysis.
1. A laboratory needs glassware for prolonged heating and sterilization, but it may also encounter strong alkali. Which comparison between borosilicate and aluminosilicate glass is accurate?
2. A technician needs to deliver a measured fraction of a pipette’s capacity. Which pipette design is suited to this task?
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