Clincal Chem Float Bench Quiz

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Accuracy
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Terms in this set (58)
Accuracy
Closeness of a test value to the true mean
Precision
Spread of replicates, or variation within the analytical method
Control
material whose physical and/or chemical compostion closely resembles the test specimen
Standard
a highly purified matieral of known composition
Standard Deviation (SD)
measure of scatter around the mean in a Gaussian distribution
Coefficient of Variation (CV)
standard deviation expressed as a percentage variance from the mean: CV=(SD/mean)*100
Internal Quality Control
a specimen with a predetermined range of result values that is processed in the same manner as patient samples; they are tested with each series or run of patient samples. Must monitor normal and abnormal levels; thus two levels of this needed for each test.
External Quality Control
performed to assure reliability of test results between different laboratories through proficiency testing or survey programs
68%
Percentage included in +-1 SDs of Gaussian distribution
95.5%
Percentage within +-2 SDs in a Gaussian distribution
99.7%Percentage within +- 3 SDs in a Gaussian distribution1. To aid in selection of a new method 2. to monitor the inherent variability (precision) of a method already in use2 Purposes of the Coefficient of Variation in a clinical labShiftsix or more consecutive results that fall on one side of the mean or the otherTrendsix consecutive results that are increasING or decreasING. This can start above or below the meana. Treated the same as patient samples b. In the normal and abnormal rangesWhich of the following statements correctly describes quality control samples? a. Treated the same as patient samples b. In the normal and abnormal ranges c. Ran by the same technologists daily d. Run at various times during the batch or shiftDelta CheckThis is a procedure in which the technologist compares two consecutive lab results on a patient (current and past). If the results differ by an amount predetermined by the lab, it has failed this procedure. The test and specimen is then question for analyzer error, preanalytical errors, specimen contamination, etc. before results are releasedIt is a coulometric titrator designed to determine chloride ion concentrations in sweat samples with just 10 nL or sweat. Sweat sample is added to an acid buffer working soln. Two silver electrodes are dipped into a vessel with working soln. The chloride in the sweat combines with the silver ions present to form AgCL precipitate. Rxn is at a constant rate, and stops when chloride ions are used up. Titration time is directly proportional to Chloride ion conc.Explain the principle of analysis of the chloridometerClean outside surfaces with bleach of cleaning agent, then dry. Over time, silver electrodes may be used up and need replaced. Before use electrodes need cleaned using blue and orange cloths, per procedure.Describe the maintenance of the ChloridometerPilocarpine iontophoresis induces sweat be stimulating sweat production (pilocarpine gel migrates into skin from a current provided by battery). The sweat is collected with a collection device and analyzed for chloride content.Explain the principle of the "macroduct" sweat testChloride (although all halides are detected, possibility for contamination)What Ion is measured in the collected sweat test?It is used in diagnosis of Cystic FibrosisWhat is the clinical significance of elevated conc. of Chloride ions in sweat?Over 60mmol/l of Chloride ion concentration is indicative of CFWhat value of sweat chloride is indicative of Cystic Fibrosis?a. Vigorously clean the skin, first with alcohol, followed by water, leaving skin slightly moist b. Apply pilocarpine gel to electrodes, then attach child's arm with Velcro straps c. Iontophorese for 5 mins d. Remove the electrodes correctly then clean area with water, then dry e. Place the collection device over the stimulated skin and collect until 3-4 rings are filled or for a maximum of 30 mins f. Transfer sweat to a small sealable container and take to lab for analysis g. (steps A-F on both arms)Summarize the steps in administration of a sweat testPatient must be older than 48 hours. Patients less than 48 hours do no have fully developed sweat glands. Additionally, patient must weigh 4.4 lbs, and is recommended to be 39 weeks corrected age (gestational + days post delivery).What are the age limitations of sweat tests and why?Possible explosion due to electric spark from battery.Why should a sweat test NOT be performed on a patient receiving oxygen?They are immunosuppressive drugs shown to be effective for the treatment of organ rejection following transplantation.What is the therapeutic use of Tacrolimus (FK506), Sirolimus (Rapamycin), and Cyclosporine?These drugs bind to the RBCsWhy is EDTA whole blood the specimen of choice for transplant drug testing?After pretreating the specimens and QC, there is a 10 min incubation at 42 deg. CWhat additional procedural step does the sirolimus assay have?The concentration of a solution expressed as the total number of solute particles per kg.Define OsmolalityThe point at which a solution starts to freeze, a "slush," an equilibrium of liquid and ice crystalsDefine freezing point related to osmometer analysisSample is put into cooling chamber. Rapid "super-cooling" is started to cool sample below its freezing point. Actual freezing initiated by vibrating probe. Freezing doesn't begin till heat is lost. There is a thermistor probe (thermometer) in the chamber that detects this released heat. This is the freezing point of the solution. The degree of freezing point depression below that of pure water is directly proportional to the total number of particles in the solution, or its osmolality.Describe the Principle of Analysis for the OsmometerChloride, sodium, glucose, urea, creatinine, and bicarbonate. Also raised by ingestion of methanol, ethanol, and isopropanol.List some common solutes responsible for increased osmolality.The ability of the kidney to concentrate or dilute urine, depending on hydration status.Measurement of simultaneous serum and urine osmolality is a "check" for what kidney function?Osmolality active solutes may be introduced by anticoagulantsWhy should plasma not be used for osmolality testing?-heparinized whole blood, in plastic syringe tubes, on ice, free of bubbles -blood may be arterial, venous, or capillary -syringes stable 30mins, capillary 5 minsState the specimen reqs and stability for blood gas analysisa. check syringe for air bubbles; if present, expel. b. mix samples thoroughly by inverting at lease 3x and rolled between outstretched palms at least 5x. Syringes is then placed on rotator/rocker for at least 2 mins c. push a few drops onto gauze pad to ensure there is no clot in syringe tipList the 3 steps of sample preparation before introducing sample into GEM blood gas analyzerInverse relationship; every degree C the temp goes down, the pH goes up by 0.0147 (due to decreased hydrogen ion activity). The opposite is trueExplain the relationship between temp and pHInverse relationship; as pCO2 increases, it combines with H2O to form carbonic acid, resulting in lowered pHExplain relationship between pCO2 and pHpCO2 in room is approx. zero, the pO2 is approx. 150mmHg, so there will be a gain of pO2 and loss of pCO2 in the specimen. The pH will thus be elevated.What is the effect of air bubbles in a blood gas specimen? (pH, pCO2, and pO2)Glycolysis will occur. Cells will utilize O2, lowering pO2, will give off CO2, raising pCO2, causing pH to dropWhat is the effect of leaving the blood gas specimen at room temp before analysis?pH = 7.35-7.45 pCO2 = 35-45 mmHg pO2 = 80-100 mmHg O2 Sat = 95-98%State the normal range for Arterial Blood Gas pH, pCO2, pO2 and O2 Sat.pH = 7.33-7.44 pCO2 = 38-50 mmHg pO2 = 35-50 mmHg O2 Sat = 60-85%State the normal range for Venous Blood Gas pH, pCO2, pO2 and O2 Sat.Metabolic processes result in production of large amounts of carbonic, sulfuric, phosphoric, and other acidsA slightly alkaline pH must be maintained to "buffer" the blood due to the body's production of hydrogen ions through what processes?Low = metabolic acidosis High = metabolic alkalosisState the clinical significance of a low and high bicarbonate (HCO3).Characterized by decreased pH and elevated pCO2. Due to respiratory depression, not enough oxygen in and CO2 out.Describe Respiratory AcidosisHow much of the hemoglobin in RBCs is carrying oxygen.What does O2 Sat measure?Checks for respiratory problems and baby's acid/base status. Testing usually only done if newborn's condition indicates they may have a breathing problemWhat are the clinical reasons for performing cord blood gas?EDTA and fluoride bind MG++ and Ca++, greatly decreasing their values.Why should EDTA and fluoride tubes never be used as an anticoagulant in Ca++ or Mg++ analyses?Any condition that alters amount of protein (albumin) available to bind calcium will make measurement of ionized calcium the better indicator of calcium status.Under what conditions is ionized calcium a better measure of calcium status than total serum concentration?The presence of ketonsWhat is the technologists looking for when performing the acetone test?For patients with type 1 diabetes during acute illness, stress, pregnancy, elevated blood glucose levels above 300 mg/dL or if patient has signs of ketoacidiosis.When is it recommended to order an acetone test?FFN is a protein found in cervical fluid secreted by fetus towards term, or when pre-term labor is potentially imminent.What is Fetal Fibronectin (FFN)? Why test?Ionized magnesium levels are critical in cardiovascular disease, metabolic stress, and neuromuscular disorders.What conditions/disease states are doctors monitoring when they order an iMg?Microalbuminuria describes small amounts of albumin in the urine. It is used to monitor nephropathy (particularly in diabetics), and can help prevent kidney disease.Define Microalbuminuria and the clinical significance>30mg/gWhat microalbumin/creatinine ratio is diagnostic of albuminuria?Urine total protein and creatinine ratio. It is an important indicator of kidney disease and pre-eclampsia in pregnant women.What is UTPCR and why is it an important test?FENA calculates the percentage of filtered sodium by the kidneys. It differentiates pre-renal azotemia from acute tubular necrosis.Diurnal significance of FENA and the condition it indicates?FEUA calculates the percentage of filtered uric acid by the kidneys. Low values (<5%) indicate Saturine Gout and High Values (>10%) indicate Fanconi syndrome.Diurnal significance of FEUA and the condition it indicates?