BG, PH, ELECTRO Q Flashcards
Which of the following represents the Henderson–Hasselbalch equation as applied to blood pH? A. pH = 6.1 + log HCO3–/PCO2 B. pH = 6.1 + log HCO3–/(0.03 × PCO2) C. pH = 6.1 + log dCO2/HCO3– D. pH = 6.1 + log (0.03 × PCO2)/HCO3
B
What is the PO2 of calibration gas containing 20.0% O2, when the barometric pressure is 30 in.? A. 60 mm Hg B. 86 mm Hg C. 143 mm Hg D. 152 mm Hg
C
What is the blood pH when the partial pressure of carbon dioxide (PCO2) is 60 mm Hg and the bicarbonate concentration is 18 mmol/L? A. 6.89 B. 7.00 C. 7.10 D. 7.30
C
Which of the following best represents the reference (normal) range for arterial pH? A. 7.35–7.45 B. 7.42–7.52 C. 7.38–7.68 D. 6.85–7.56
A
What is the normal ratio of bicarbonate to dissolved carbon dioxide (HCO3–:dCO2) in arterial blood? A. 1:10 B. 10:1 C. 20:1 D. 30:1
C
What is the PCO2 if the dCO2 is 1.8 mmol/L? A. 24 mm Hg B. 35 mm Hg C. 60 mm Hg D. 72 mm Hg
C
In the Henderson–Hasselbalch expression pH = 6.1 + log HCO3–
/dCO2, the 6.1 represents:
A. The combined hydration and dissociation constants for CO2 in blood at 37°C
B. The solubility constant for CO2 gas
C. The dissociation constant of H2O
D. The ionization constant of sodium bicarbonate (NaHCO3)
A
Which of the following contributes the most to the serum total CO2? A. PCO2 B. dCO2 C. HCO3– D. Carbonium ion
C
In addition to sodium bicarbonate, what other substance contributes most to the amount of base in the blood? A. Hemoglobin concentration B. Dissolved O2 concentration C. Inorganic phosphorus D. Organic phosphate
A
Which of the following effects results from exposure of a normal arterial blood sample to room air?
A. PO2 increased PCO2 decreased pH increased
B. PO2 decreased PCO2 increased pH decreased
C. PO2 increased PCO2 decreased pH decreased
D. PO2 decreased PCO2 decreased pH decreased
A
Which of the following formulas for O2 content is correct?
A. O2 content = %O2 saturation/100 × Hgb g/dL ×1.39 mL/g + (0.0031 × PO2)
B. O2 content = PO2 × 0.0306 mmol/L/mm
C. O2 content = O2 saturation × Hgb g/dL × 0.003 mL/g
D. O2 content = O2 capacity × 0.003 mL/g
A
The normal difference between alveolar and arterial PO2 (PAO2–PaO2 difference) is: A. 3 mm Hg B. 10 mm Hg C. 40 mm Hg D. 50 mm Hg
B
A decreased PAO2–PaO2 difference is found in:
A. A/V (arteriovenous) shunting
B. V/Q (ventilation/perfusion) inequality
C. Ventilation defects
D. All of these options
C
The determination of the oxygen saturation of hemoglobin is best accomplished by:
A. Polychromatic absorbance measurements of a whole-blood hemolysate
B. Near infrared transcutaneous absorbance measurement
C. Treatment of whole blood with alkaline dithionite prior to measuring absorbance
D. Calculation using PO2 and total hemoglobin by direct spectrophotometry
A
Correction of pH for a patient with a body temperature of 38°C would require: A. Subtraction of 0.015 B. Subtraction of 0.01% C. Addition of 0.020 D. Subtraction of 0.020
A
Select the anticoagulant of choice for blood gas studies. A. Sodium citrate 3.2% B. Lithium heparin 100 U/mL blood C. Sodium citrate 3.8% D. Ammonium oxalate 5.0%D
B
What is the maximum recommended storage time and temperature for an arterial blood gas sample drawn in a plastic syringe? Storage Time Temperature A. 10 min 2°C–8°C B. 20 min 2°C–8°C C. 30 min 2°C–8°C D. 30 min 22°C
D
A patient’s blood gas results are as follows:
pH = 7.26 dCO2 = 2.0 mmol/L HCO3– = 29 mmol/L
These results would be classified as:
A. Metabolic acidosis
B. Metabolic alkalosis
C. Respiratory acidosis
D. Respiratory alkalosis
C
A patient’s blood gas results are: pH = 7.50 PCO2 = 55 mm Hg HCO3– = 40 mmol/L These results indicate: A. Respiratory acidosis B. Metabolic alkalosis C. Respiratory alkalosis D. Metabolic acidosis
B
Which set of results is consistent with uncompensated respiratory alkalosis? A. pH 7.70 HCO3 30 mmol/L PCO2 25 mm Hg B. pH 7.66 HCO3 22 mmol/L PCO2 20 mm Hg C. pH 7.46 HCO3 38 mmol/L PCO2 55 mm Hg D. pH 7.36 HCO3 22 mmol/L PCO2 38 mm Hg
B
Which of the following will shift the O2 dissociation curve to the left? A. Anemia B. Hyperthermia C. Hypercapnia D. Alkalosis
D
In which circumstance will the reporting of calculated oxygen saturation of hemoglobin based on PO2, PCO2, pH, temperature, and
hemoglobin be in error?
A. Carbon monoxide poisoning
B. Diabetic ketoacidosis
C. Patient receiving oxygen therapy
D. Assisted ventilation for respiratory failure
A
Which would be consistent with partially compensated respiratory acidosis?
A. pH PCO2 Bicarbonate
increased increased increased
B. pH PCO2 Bicarbonate
increased decreased decreased
C. pH PCO2 Bicarbonate
decreased decreased decreased
D. pH PCO2 Bicarbonate
decreased increased increased
D
Which condition results in metabolic acidosis with severe hypokalemia and chronic alkaline urine? A. Diabetic ketoacidosis B. Phenformin-induced acidosis C. Renal tubular acidosis D. Acidosis caused by starvation
C
Which of the following mechanisms is responsible for metabolic acidosis? A. Bicarbonate deficiency B. Excessive retention of dissolved CO2 C. Accumulation of volatile acids D. Hyperaldosteronism
A
Which of the following disorders is associated with lactate acidosis? A. Diarrhea B. Renal tubular acidosis C. Hypoaldosteronism D. Alcoholism
D
Which of the following is the primary mechanism of compensation for metabolic acidosis? A. Hyperventilation B. Release of epinephrine C. Aldosterone release D. Bicarbonate excretion
A
The following conditions are all causes of alkalosis. Which condition is associated with respiratory (rather than metabolic) alkalosis? A. Anxiety B. Hypovolemia C. Hyperaldosteronism D. Hypoparathyroidism
A
Which of the following conditions is associated
with both metabolic and respiratory alkalosis?
A. Hyperchloremia
B. Hypernatremia
C. Hyperphosphatemia
D. Hypokalemia
D
In uncompensated metabolic acidosis, which of the following will be normal? A. Plasma bicarbonate B. PCO2 C. p50 D. Total CO2
B
Which of the following conditions is classified as normochloremic acidosis? A. Diabetic ketoacidosis B. Chronic pulmonary obstruction C. Uremic acidosis D. Diarrhea
A
Which PCO2 value would be seen in maximally compensated metabolic acidosis? A. 15 mm Hg B. 30 mm Hg C. 40 mm Hg D. 60 mm Hg
A
A patient has the following arterial blood gas results: pH = 7.56 PCO2 = 25 mm Hg PO2 = 100 mm Hg HCO3– = 22 mmol/L These results are most likely the result of which condition? A. Improper specimen collection B. Prolonged storage C. Hyperventilation D. Hypokalemia
C
Why are three levels used for quality control of pH and blood gases?
A. Systematic errors can be detected earlier than with two controls
B. Analytical accuracy needs to be greater than for other analytes
C. High, normal, and low ranges must always be evaluated
D. A different level is needed for pH, PCO2, and PO2
A
A single-point calibration is performed between each blood gas sample in order to:
A. Correct the electrode slope
B. Correct electrode and instrument drift
C. Compensate for temperature variance
D. Prevent contamination by the previous sample
B
In which condition would hypochloremia be expected? A. Respiratory alkalosis B. Metabolic acidosis C. Metabolic alkalosis D. All of these options
C
Given the following serum electrolyte data, determine the anion gap.
Na = 132 mmol/L Cl = 90 mmol/L HCO3– = 22 mmol/L
A. 12 mmol/L
B. 20 mmol/L
C. 64 mmol/L
D. Cannot be determined from the information provided
B
Which of the following conditions will cause an increased anion gap? A. Diarrhea B. Hypoaldosteronism C. Hyperkalemia D. Renal failure
D
Alcoholism, liver failure, and hypoxia induce acidosis by causing: A. Depletion of cellular NAD+ B. Increased excretion of bicarbonate C. Increased retention of PCO2 D. Loss of carbonic anhydrase
A
Which of the following is the primary mechanism causing respiratory alkalosis? A. Hyperventilation B. Deficient alveolar diffusion C. Deficient pulmonary perfusion D. Parasympathetic inhibition
A
Which condition can result in acidosis? A. Cystic fibrosis B. Vomiting C. Hyperaldosteronism D. Excessive O2 therapy
D
Which of the following conditions is associated with an increase in ionized calcium (Cai) in the blood? A. Alkalosis B. Hypoparathyroidism C. Hyperalbuminemia D. Malignancy
D
Which of the following laboratory results is consistent with primary hypoparathyroidism?
A. Low calcium; high inorganic phosphorus Pi
B. Low calcium; low Pi
C. High calcium; high Pi
D. High calcium; low Pi
A
Which of the following conditions is associated with hypophosphatemia? A. Rickets B. Multiple myeloma C. Renal failure D. Hypervitaminosis D
A
Which of the following tests is consistently abnormal in osteoporosis?
A. High urinary calcium
B. High serum Pi
C. Low serum calcium
D. High urine or serum N-telopeptide of type 1 collagen
D
Which of the following is a marker for bone formation?
A. Osteocalcin
B. Tartrate resistant acid phosphatase (TRAP)
C. Urinary pyridinoline and deoxypyridinoline
D. Urinary C-telopeptide and N-telopeptide crosslinks (CTx and NTx)
A
What role do CTx and NTx play in the management of osteoporosis?
A. Increased urinary excretion is diagnostic of early stage disease
B. Increased levels indicate a low risk of developing osteoporosis
C. Decreased urinary excretion indicates a positive response to treatment
D. The rate of urinary excretion correlates with the stage of the disease
C
What role does vitamin D measurement play in the management of osteoporosis?
A. Vitamin D deficiency must be demonstrated to establish the diagnosis
B. Vitamin D is consistently elevated in osteoporosis
C. A normal vitamin D level rules out osteoporosis
D. Vitamin D deficiency is a risk factor for developing osteoporosis
D
Which statement best describes testing recommendations for vitamin D?
A. Vitamin D testing should be reserved only for those persons who demonstrate hypercalcemia of an undetermined cause
B. Vitamin D testing should be specific for the 1,25(OH)D3 form
C. Testing should be for total vitamin D when screening for deficiency
D. Vitamin D testing should not be performed if the patient is receiving a vitamin D supplement
C
The serum level of which of the following laboratory tests is decreased in both VDDR and VDRR? A. Vitamin D B. Calcium C. Pi D. Parathyroid hormone
C
Which of the following is the most accurate measurement of Pi in serum?
A. Rate of unreduced phosphomolybdate formation at 340 nm
B. Measurement of phosphomolybdenum blue at 680 nm
C. Use of aminonaptholsulfonic acid to reduce phosphomolybdate
D. Formation of a complex with malachite green dye
A
What is the percentage of serum calcium that is ionized (Cai)? A. 30% B. 45% C. 60% D. 80%
B
Which of the following conditions will cause erroneous Cai results? Assume that the samples are collected and stored anaerobically, kept at 4°C until measurement, and stored for no longer than 1 hour.
A. Slight hemolysis during venipuncture
B. Assay of whole blood collected in sodium oxalate
C. Analysis of serum in a barrier gel tube stored at
4°C until the clot has formed
D. Analysis of whole blood collected in sodium heparin, 20 U/mL (low-heparin tube)
B
Which of the following conditions is associated with a low serum magnesium? A. Addison’s disease B. Hemolytic anemia C. Hyperparathyroidism D. Pancreatitis
D
When measuring calcium with the complexometric dye o-cresolphthalein complexone, magnesium is kept from interfering by: A. Using an alkaline pH B. Adding 8-hydroxyquinoline C. Measuring at 450 nm D. Complexing to EDTA
B
Which electrolyte measurement is least affected by hemolysis? A. Potassium B. Calcium C. Pi D. Magnesium
B
Which of the following conditions is associated with hypokalemia? A. Addison’s disease B. Hemolytic anemia C. Digoxin intoxication D. Alkalosis
D
Which of the following conditions is most likely to produce an elevated plasma potassium? A. Hypoparathyroidism B. Cushing’s syndrome C. Diarrhea D. Digitalis overdose
D
Which of the following values is the threshold critical value (alert or action level) for low plasma potassium? A. 1.5 mmol/L B. 2.0 mmol/L C. 2.5 mmol/L D. 3.5 mmol/L
C
Which electrolyte is least likely to be elevated in renal failure? A. Potassium B. Magnesium C. Inorganic phosphorus D. Sodium
D
Which of the following is the primary mechanism for vasopressin (ADH) release? A. Hypovolemia B. Hyperosmolar plasma C. Renin release D. Reduced renal blood flow
B
Which of the following conditions is associated with hypernatremia? A. Diabetes insipidus B. Hypoaldosteronism C. Burns D. Diarrhea
A
Which of the following values is the threshold critical value (alert or action level) for high plasma sodium? A. 150 mmol/L B. 160 mmol/L C. 170 mmol/L D. 180 mmol/L
B
Which of the following conditions is associated with total body sodium excess? A. Renal failure B. Hyperthyroidism C. Hypoparathyroidism D. Diabetic ketoacidosis
A
Which of the following conditions is associated with hyponatremia? A. Diuretic therapy B. Cushing’s syndrome C. Diabetes insipidus D. Nephrotic syndrome
A
Which of the following conditions involving electrolytes is described correctly?
A. Pseudohyponatremia occurs only when undiluted samples are measured
B. Potassium levels are slightly higher in heparinized plasma than in serum
C. Hypoalbuminemia causes low total calcium but does not affect Cai
D. Hypercalcemia may be induced by low serum
magnesium
C
Which of the following laboratory results is usually associated with cystic fibrosis? A. Sweat chloride greater than 60 mmol/L B. Elevated serum sodium and chloride C. Elevated fecal trypsin activity D. Low glucose
A
When performing a sweat chloride collection, which of the following steps will result in analytical error?
A. Using unweighed gauze soaked in pilocarpine nitrate on the inner surface of the forearm to stimulate sweating
B. Collecting more than 75 mg of sweat in 30 minutes
C. Leaving the preweighed gauze on the inside of the arm exposed to air during collection
D. Rinsing the collected sweat from the gauze pad using chloride titrating solution
C
Which electrolyte level best correlates with plasma osmolality? A. Sodium B. Chloride C. Bicarbonate D. Calcium
A
Which formula is most accurate in predicting plasma osmolality? A. Na + 2(Cl) + BUN + glucose B. 2(Na) + 2(Cl) + glucose + urea C. 2(Na) + (glucose ÷ 18) + (BUN ÷ 2.8) D. Na + Cl + K + HCO3
C
Which formula is most accurate in predicting plasma osmolality? A. Na + 2(Cl) + BUN + glucose B. 2(Na) + 2(Cl) + glucose + urea C. 2(Na) + (glucose ÷ 18) + (BUN ÷ 2.8) D. Na + Cl + K + HCO3
