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Terms in this set (194)
Following overnight fasting hypoglycemia adults is defined as a glucose of
< or equal to 45 mg/dL
The preparation of a patient for standard glucose tolerance testing should include
A high carbohydrate diet for 3 days
If a fasting glucose was 90 mg/dL, what 2-hour postprandial glucose results would most closely represent normal glucose metabolism?
A healthy person with a blood glucose of 80 mg/dL would have a simultaneously determined CSF glucose of
A 25 year old man became nauseated and vomitted 90 minutes after receiving a standard 75 g carbohydrate dose for an oral glucose tolerance test. The best course of action is to
Draw blood for glucose and discontinue test
CSF for glucose assay should be
What 2 hour postprandial glucose values demonstrates unequivocal hyperglycemia diagnostic for diabetes mellitus?
Serum levels that define hypoglycemia in pre-term or low birth weight infants are
Lower than adults
A 45 year old woman has a fasting serum glucose concentration of 95 mg/dL and a 2 hour postprandial glucose concentration of 105 mg/dL. The statement that best describes this patient's fasting serum glucose concentration is
Normal; reflecting glycogen breakdown by the liver
Pregnant women with symptoms of thirst, frequent urination or unexplained weight loss should have what test performed?
Glucose tolerance test
In the fasting state, the arterial and capillary blood glucose concentration varies from the venous glucose concentration by approximately how many mg/dL?
5 mg/dL higher
The conversion of glucose or other hexoses into lactate or pyruvate is called
What values obtained during a glucose tolerance test are diagnostic of diabetes mellitus?
Fasting plasma glucose: 126 mg/dL
The glycated hemoglobin value represents the integrated values of glucose concentration during the preceding
Monitoring long-term glucose control in patients with adult onset diabetes mellitus can best be accomplished by measuring
Total glycolylated hemoglobin levels in a hemolysate reflect the
Average blood glucose levels of the past 2-3 months
What hemoglobin has glucose-6-phosphate on the amino-terminal valine of the beta chain?
A patient with hemolytic anemia will
Show a decrease in glycated Hgb value
In using ion-exchange chromatographic methods, falsely increased levels of Hgb A1c might be demonstrated in the presence of
An increase in serum acetone is indicative of a defect in the metabolism of
An infant with diarrhea is being evaluated for a carbohydrate intolerance. His stool yields a positive copper reduction test and a pH of 5.0. It should be concluded that
Further tests are indicated
Blood samples were collected at the beginning of an exercise class and after 30 minutes of aerobic activity. What would be most consistent with the post-exercise sample?
Elevatic lactic acid, elevated pyruvate
What is the best method to diagnose lactase deficiency?
H2 breath test
The expected blood gas results for a patient in chronic renal failure would match the pattern of
Severe diarrhea causes
Factors that contribute to a PCO2 electrode requiring 60-120 seconds to reach equilibrium include the
Diffusion characteristics of the membrane
An emphysema patient suffering from fluid accumulation in the alveolar spaces is likely to be in what metabolic state?
At blood pH 7.40, what is the ratio of bicarbonate to carbonic acid?
The reference range for the pH of arterial blood measured at 37 degrees celcius is
A 68 year old man arrives in the ER with a glucose level of 722 mg/dL and serum acetone of 4+ undiluted. An arterial blood gas from this patient is likely to be
A patient is admitted to the ER in a state of metabolic alkalosis. What would be consistent with this diagnosis?
High TCO2, increased HCO3
A person suspected of having metabolic alkalosis would have what lab findings?
CO2 content and pH elevated
Metabolic acidosis is described as a(n)
Decrease in CO2 content and PCO2 with a decreased pH
Respiratory acidosis is described as a(n)
Increase in CO2 content and PCO2 with a decreased pH
A common cause of respiratory alkalosis is
Acidosis and alkalosis are best defined as fluctuations in blood pH and CO2 content due to changes in
A blood gas sample was sent to the lab on ice and a bubble was present in the syringe. The blood had been exposed to room air for at least 30 minutes. What change in blood gases will occur?
PO2 increased/ HCO3 decreased
What test evaluates renal tubular function?
The degree to which the kidney concentrates the glomerular filtrate can be determined by
Urine to serum osmolality ratio
Osmolal gap is the difference between
Calculated and measured osmolality ratio
The most important bufferpair in plasma is the
Bicarbonate/carbonic acid pair
Quantitation of Na+ and K+ by ion-selective electrode is the standard method because
Of advances in electrochemistry
What battery of tests is most useful in evaulating an anion gap of 22 mEq/L?
BUN, creatinine, salicylate, and methanol
Most of the carbon dioxide present in blood is the form of
Serum "anion gap" is increased in patients with
The anion gap is useful for QC of lab results for
Sodium, potassium, chloride and total CO2
The buffering capacity of blood is maintained by a reversible exchange process between bicarbonate and
What electrolyte is the chief plasma cation whose main function is maintaining osmotic pressure?
A potassium level of 6.8 mEq/L is obtained. Before reporting the results, the first step the tech should take is to
Check the serum for hemolysis
The solute that contributes the most to the total serum osmolality is
A sweat chloride result of 55 mEq/L and a sweat sodium of 52 mEq/L were obtained on a patient who has a history of respiratory problems. The best interpretation of these results is
Borderline results, the test should be repeated
What is true about direct ion selective electrodes for electrolytes?
Whole blood specimens are acceptable
Sodium determination by indirect ion selective electrode is falsely decreased by
Elevated lipid levels
A physician requested that electrolytes on a multiple myeloma patient specimen be run by direct ISE and not indirect ISE because
Na is falsely decreased by indirect ISE
Calcium concentration in the serum is regulated by
The regulation of calcium and phosphorous metabolism is accomplished by what glands?
A patient has the following test results: increased serum calcium levels decreased serum phosphate levels, and increased levels of parathyroid hormone. This patient most likely has
A hospitalized patient is experiencing increased neuromuscular irritability (tetany). What test should be ordered immediately?
What is most likely to be ordered in addition to serum calcium to determine the cause of tetany?
A reciprocal relationship exists between
Calcium and phosphate
Fasting serum phosphate concentration is controlled primarily by the
A low concentration of serum phosphorus is commonly found in
Patients who are receiving carbohydrate hyperalimentation
The primary function of serum albumin in the peripheral blood is to
Maintain collidal osmotic pressure
The first step in analyzing a 24 hour urine specimen for quantitative urine protein is
Measure the total volume
Total iron-binding capacity measures the serum iron transporting capacity of
The first step in the quantitation of serum iron is
Separation of iron from transferring
To assure an accurate ammonia level result, the specimen should be
Spun, separated, iced, and tested immediately
Erroneous ammonia levels can be eliminated by what?
Assuring water and reagents are ammonio-free; separating plasma from cells and performing test analysis asap; and drawing the specimen in a prechilled tube and immersing the tube in ice
A serum sample demonstrates an elevated result when tested with the Jaffe reaction.This indicates
Renal functional impairment
Creatinine clearance is used to estimate the
Glomerular filtration rate
A blood creatinine value of 5.0 mg/dL is most likely to be found with what blood value?
Urea nitrogen: 80 mg/dL
90% of the copper present in the blood is bound to
Hemoglobin S can be separated from hemoglobin D by
Electrophoresis on a different medium and acidic pH
On electrophoresis at alkaline pH, what is the slowest migrating hemoglobin?
Urobilinogen is formed in the
A serum sample was assayed for bilirubin at 10 AM and the result was 12 mg/dL. The same sample was retested at 3 PM. The result now is 8 mg/dL. The most likely explanation for this discrepancy is
The sample was exposed to light
Kernicterus is an abnormal accumulation of bilirubin in
A stool specimen that appears black and tarry should be tested for the presence of
The most specific enzyme test for acute pancreatitis is
What enzymes are used in the diagnosis of acute pancreatitis?
Amylase (AMS) and Lipase (LPS)
A physician suspects his patient has pancreatitis. What test would be most indicative of this disease?
Aspartate amino transferase (AST) is characteristically elevated in diseases of the
Amino transferase enzymes catalyze the
Exchange of amino and keto groups between alpha-amino and alpha-keto acids
Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) are both elevated in what disease?
The greates activities of serum AST and ALT are seen in what?
Acute viral hepatitis
What clinical disorder is associated with the greatest elevation of lactate dehydrogenase isoenzyme 1?
The enzyme, which exists chiefly in skeletal muslce, heart, and brain, is grossly elevated in active muscuar dystrophy, and rises early in myocardial infarction is
The enzyme present in almost all tissues that may be separated by electrophoresis into 5 components is
A common cause of a falsely increased LD1 fraction of lactic dehydrogenase is
The presence of what isoenzyme indicates acute myocardial damage?
In what condition would a normal level of creatine kinase be found?
The disease most often associated with elevation of lactate dehydrogenase isoezymes 4 and 5 on electrophoresis is
When myocardial infarction occurs, the first enzyme to become elevated is
A scanning of a CK isoenzyme fractionation revealed 2 peaks: a slow cathodic peak (CKMM) and an intermediate peak (CKMB). A possible interpretation for this pattern is
A 10 year old child was admitted to pediatrics with an initial diagnosis of skeletal muscle disease. The best confirmatory test would be
Aldolase and creatine
In the immunoinhibition phase of the CKMB procedure
M subunit is inactivated
The presence of increased CKMB activity on a CKMB activity on a CK electrophoresis pattern is most likely found in a patient suffering from
Increased serum lactic dehydrogenase activity due to elevation of fast fraction (1and 2) on electrophoretic separation is cuased by
What specimen preparation is commonly used to perform the alkaline phosphatase isoenzyme determination?
Serum is divided into 2 aliquots, on is frozen, and the other is refrigerated
Regan isoenzyme has the same properties as alkaline phosphatase that originates in the
The most heat labile fraction of alkaline phosphatase is obtained from
The most sensitive enzymatic indicator for liver damagae from ethanol intake is
Gamma-glutamyl transferase (GGT)
Isoenzyme assays are performed to improve
The protein portion of an enzyme complex is called the
What chemical determination may be of help in establishing the presence of seminal fluid?
Chylomicrons are present in what dyslipidemias?
Deficiency in lipoprotein lipase activity
Turbidity in serum suggests elevation of
TSH is produced by the
A 45 year old woman complains of fatigue, heat intolerance, and hair loss. Total and free T4 are abnormally low. If the TSH showed marked elevation, this would be consistent with
The majority of thyroxine (T4) is converted into the more biologically active hormone
A 2 year old child with a decreased serum T4 is described as being somewhat dwarfed, stocky, overweight, and having coarse features. The most informative additional lab test would be the serum
Thyroid-Stimulating hormone (TSH)
The recommended initial thyroid function test for either a healthy, asymptomatic patient or a patient with symptoms which may be related to a thyroid disorder is
Thyroid-stimulating hormone (TSH)
The screening test for congenital hypothyroidism is based upon
Total thyroxine (T4) level in the newborn
A 68 year old female patient tells her physician of being "cold all the time" and recent weight gain, with no change in diet. THe doctor orders a TSH level, and the lab reports a value of 8.7 uU/mL. This patient most likely has
What is secreted by the placenta and used for the early detection of pregnancy?
Human chorionic gonadotropin (HCG)
In amniotic fluid, the procedure used to detect hemolytic disease of the newborn is
Measurement of absorbance at 450 nm
During a normal pregnancy, quantitative human chorionic gonadotropin (HCG) levels peak how many weeks after the last menstrual period?
What steriod is an adrenal cortical hormone?
What common substrate is used in the biosynthesis of adrenal steroids, including androgens and estrogens?
Plasma for cortisol determinations were collected at 7 am, after waking the patient, and at 10 PM that evening. The cortisol level of the morning sample was higher than the evening sample. This is consistent with
A normal finding
Night blindness is associated with deficiency of what vitamin?
Beriberi is assoicated with deficiency of vitamin
Scurvy is associated with deficiency of what vitamin
Rickets is associated with deficiency of what vitamin?
Pellagra is associated with deficiency of what vitamin?
The major action of angiotensin 2 is
The urinary excretion product measured as an indicator of epinephrine production is
Vanillylmandelic acid (VMA)
What hormone regulates normal blood calcium levels?
A diagnosis of primary adrenal insufficiency requires demonstration of
Impaired response to ACTH stimulation
The screen for adrenal cortical hyperfunction with the greates sensitivity and specificity is
24- hour urine free cortisol
What sample collection would give an accurate assessment of potential excess cortisol production (hypercortisolism)?
Collect a 24 hour urine free cortisol
Aldosterone is released by the adrenal cortex upon stimulation by
Clinical assays for tumor markers are most important for
Monitoring the course of a known cancer
Detection of what substance is most useful to monitor the course of a patient with testicular cancer?
Increased concentrations of alpha-fetoprotein (AFP) in adults are most characteristically associated with
Carcinoembryonic antigen (CEA) is most likely to be produced in a malignancy involving the
What is useful in the detection and mangement of carcinoma of the prostate?
Total prostate-specific antigen
Cancer antigen 125 (CA 125) is a tumor marker associated with
Ovarian and endometrial carcinoma
In addition to carcinoma of the prostate-specific antigen (PSA) can occur due to
Benign prostatic hyperplasia
A drug has a half-life of 6 hours. If a dose is given every 6 hours, a steady-state drug level would usually be achieved in
The drug procainamide is prescribed to treat cardiac arrhythmia. What biologically active liver metabolite of procainamide is often measured simultaneously?
N-acetyl procainamide (NAPA)
Cocaine is metabolized to
The metabolite 11-nor-tetrahydrocannabinol-9-COOH can be detected by immunoassay 3-5 days after a single use of
A 3 year old child was evaluated for abdominal pain and anorexia by a physician. A CBC revealed a hemoglobin of 9.8 g/dL and basphilic stippling of the RBCs. The doctor should order further tests to check for poisoning from
A carbonate salt used to control manic-depressive disorders is
An antiepileptic (or anticonvulsant) used to control seizure disoders is
A drug that relaxes the smooth muscles of the bronchial passages is
A cardiac glycoside that is used in the treatment of congenital heart failure and arrhythmias by increasing the force and velocity of myocardial contraction is
A salicylate level is performed to detect toxicity caused by ingestion of excess
Lithium therapy is widely used in the treatment of
Manic-depressive (bipolar) disorder
Testing for the diagnosis of lead poisoning should include
Whole blood lead
In a specimen collected for plasma glucose analysis, sodium fluoride
Blood was collected in a serum separator tube on a patient who has been fasting since midnight. The time of collection was 7 am. The lab test which should be recollected is
What serum constituent is unstable if a blood specimen is left at RT for 8 hours before processing?
Unless blood gas measurements are made immediately after sampling, in vitro glycolysis of the blood causes a
Fall in pH and a rise in PCO2
An arterial blood specimen submitted for blood gas analysis was obtained at 830 am but was not received in the lab until 11 am. The tech should
Request a new arterial specimen be obtained
A 24 hour urine specimen (total volume: 1,136 mL) is submitted to the lab for quantitative urine protein. Calculate the amount of protein excreted per day, if the toal protein is 52 mg/dL.
What is the formula for calculating absorbance given the percent transmittance (%T) of a solution?
What is the Henderson-Hasselbalch equation?
The creatinine clearance (mL/min) is equal to
(urinary creatinine (mg/L)x volume (mL/min))/ plasma creatinine (mg/L)
Normally the bicarbonate concentration is about 24 mEq/L and the carbonic acid concentration is about 1.2; pK=6.1, log 20=1.3. Using the equation pH=pK+log (salt)/(acid), calcuate the pH.
What method is susceptible to the solvent displacing effect that results in falsely decreased electrolyte values?
Indirect ion selective electrodes
To detect barbiturate abuse when anlyzing urine specimens, immunoassay is the method of choice for screening. The method of choice for confirmation is
Gas chromatography/mass spectrometry
When separating serum proteins by cellulose acetate electrophoresis, using Veronal buffer at pH 8.6, beta globulin migrates
Faster than gamma globulin
Hemoglobin S can be separated from hemoglobin D by what method?
Agar gel electrophoresis at pH 5.9
What is the proper pH for the buffered solution used to perform serum protein electrophoresis?
The buffer pH most effective at allowing amphoteric proteins to migrate toward the cathode in an electrophoretic system would be
An electrode has a silver/silver chloride anode and a patinum wire cathode. It is suspended in KCl solution and separated from the blood to be analyzed by a selectively permeable membrane. Such an electrode is used to measure what?
Hydrogen ion concentration (pH) in blood is usually determined by means of what electrode?
An automated method for measuring chloride which generates silver ions in the reaction is
Coulometry is often used to measure
Chloride in sweat
In a pH meter reference electrodes may include
Most automated blood gas analyzers directly measure
pH, PCO2, and PO2
Blood PCO2 may be measured by
A self-contained potentiometric electrode
Valinomycin enhances the selectivity of the electrode used to quantitate
What blood gas electrode is composed of silver/silver chloride refernce electrode and glass?
Most chemical methods for dtermining total protein utilize what reaction?
Bromcresol purple at a pH of 5.2 is used in a colorimetric method to measure
Magnesium carbonate is added in an iron binding capacity determination in order to
Remove excess unbound iron
The most specific method for the assy of glucose utilizes
What calcium procedures utilizes lanthanum chloride to eliminate interfering substances?
Atomic absorption spectrophotometry
Before unconjugated bilirubin can react with Ehrlich diazo reagent, what must be added?
The most widely used methods for bilirubin measurement are thosed based on the
In the Malloy and Evelyn method for the determination of bilirubin, the reagent that is reacted with bilirubin to form a purple azobilirubin is
Diazotized sulfanilic acid
In the Jendrassik-Grof reaction for total bilirubin, bilirubin reacts with diazotized sulfanilic acid to form
In the assay of lactate dehydrogenase, what product is actually measured?
In the assay of lactate dehydrogenase (LD) the reaction is dependent upon what coenzyme systems?
The International Federation for Clinical Chemistry (IFCC) recommends the use of methods such as the Bessey-Lowry-Brock method for dtermining alkaline phosphatase activity. The substate used in this type of method is
What is a glycolytic enzyme that catalyzes the cleavage of fructose-1, 6-diphosphate to glyceraldehyde-3-phosphate, and dihydroxyacetone phosphate?
The substance that is measured to estimate the serum concentration of triglycerides by most methods is
What method for quantitation og high-density lipoprotein is most suited for clinical lab use?
A chemiluminescent EIA
Is quantitated by the amount of light produced by the reaction
The osmolality of a urine or serum specimen is measured by a change in the
What applies to cryoscopic osmometry?
Temperature at equilibrium is a function of the number of particles in solution
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