Clinical Chemistry (Electrolytes and Osmolality)

Question 1

What is the normal renal threshold of sodium (measured in millimoles per liter)?

A. 80-85
B. 90-110
C. 110-130
D. 135-148

Question 2

Of the total serum osmolality, sodium, chloride, and bicarbonate ions normally contribute approximately what percent?

A. 8
B. 45
C. 75
D. 92

Question 3

The presence of only slightly visible hemolysis will significantly increase the serum level of which of the following electrolytes?

A. Sodium
B. Potassium
C. Chloride
D. Bicarbonate

Question 4

Which of the following is not a component of the total anion content of serum?

A. Acetoacetate
B. Protein
C. Lactate
D. Iron

Question 5

Which of the following is not associated with potassium?

A. Has no renal threshold
B. Increased serum level in acidosis
C. Hemolysis causes false increase in
serum levels
D. Major anion of intracellular fluid

Question 6

Which of the following is a spectrophotometric method for quantifying serum chloride?

A. Ferric perchlorate
B. Ammonium molybdate
C. Bathophenanthroline
D. Cresolphthalein complexone

Question 7

Which of the following statements is false about the electrolyte chloride?

A. Main anion of the extracellular fluid
B. Can shift from the extracellular plasma to the intracellular fluid of red blood cells
C. Unable to be reabsorbed by active transport
D. Measured in serum, urine, and sweat

Question 8

Using the following data: Na+ = 143
mmol/L; K+ = 4.9 mmol/L; Cl- = 105
mmol/L; and HCO-3 = 25 mmol/L, which
of the following statements is false?

A. Patient results are not acceptable.
B. Anion gap is useful in detecting some disease states.
C. Anion gap equals 18 mmol/L.
D. Anion gap is useful for checking analytical error

Question 9

A patient presents with Addison disease. Serum sodium and potassium analyses are performed. What would the results reveal?

A. Normal sodium, low potassium levels
B. Low sodium, low potassium levels
C. Low sodium, high potassium levels
D. High sodium, low potassium levels

Question 10

Primary aldosteronism results from a tumor of the adrenal cortex. How would the extracellular fluid be affected?

A. Normal sodium, decreased potassium levels
B. Decreased sodium, decreased potassium levels
C. Decreased sodium, increased potassium levels
D. Increased sodium, decreased potassium levels

Question 11

Which of the following conditions is not associated with hyponatremia?

A. Addison disease
B. Diarrhea
C. Diuretic therapy
D. Gushing syndrome

Question 12

Of the total serum calcium, free ionized
calcium normally represents approximately what percent?

A. 10
B. 40
C. 50
D. 90

Question 13

Measuring the tubular reabsorption of phosphate is useful in diagnosing diseases that affect which of the following organs?

A. Liver
B. Adrenal gland
C. Thyroid gland
D. Parathyroid gland

Question 14

Which of the following does not have an effect on plasma calcium levels?

A. Parathyroid hormone
B. Vitamin D
C. Calcitonin
D. Aldosterone

Question 15

Which of the following is an effect of increased parathyroid hormone secretion?

A. Decreased blood calcium levels
B. Increased renal reabsorption of phosphate
C. Decreased bone resorption
D. Increased intestinal absorption of calcium

Question 16

The following laboratory results are obtained on a 60-year-old woman who is complaining of anorexia, constipation, abdominal pain, nausea, and vomiting:

Ionized serum calcium—elevated
Serum inorganic phosphate— decreased
Urine calcium—elevated
Urine phosphate—elevated

What do these results suggest?

A. Primary hyperparathyroidism
B. Vitamin D deficiency
C. Hypoparathyroidism
D. Paget disease

Question 17

Secondary hyperparathyroidism is often the result of

A. Vitamin C deficiency
B. Liver disease
C. Renal disease
D. Thyroid disease

Question 18

Which of the following reagents is used to determine the concentration of serum inorganic phosphate?

A. Ehrlich’s reagent
B. Ammonium molybdate
C. 8-Hydroxyquinoline
D. Bathophenanthroline

Question 19

Which of the following reagents is used in a colorimetric method to quantify the concentration of serum calcium?

A. Cresolphthalein complexone
B. Lanthanum
C. Malachite green
D. Amino-naphthol-sulfonic acid

Question 20

Which of the following has an effect on plasma calcium levels?

A. Sodium
B. Inorganic phosphate
C. Potassium
D. Iron

Question 21

A patient’s serum inorganic phosphate level is found to be elevated but the physician cannot determine a physiological basis for this abnormal result. What could possibly have caused an erroneous result to be reported?

A. Patient not fasting when blood was drawn
B. Specimen was hemolyzed
C. Effect of diurnal variation
D. Patient receiving intravenous glucose therapy

Question 22

To what metal does ceruloplasmin firmly bind?

A. Chromium
B. Copper
C. Zinc
D. Iron

Question 23

In iron-deficiency anemia, what would be the expected percent saturation of transferrin with iron?

A. Less than 15
B. Between 30 and 40
C. Between 40 and 50
D. Greater than 55

Question 24

What is the primary storage form of iron?

A. Apotransferrin
B. Myoglobin
C. Ferritin
D. Hemosiderin

Question 25

A serum ferritin level may not be a useful indicator of iron-deficiency anemia in patients with what type of disorder?

A. Chronic infection
B. Malignancy
C. Viral hepatitis
D. All the above

Question 26

Which of the following chromogens will not produce a colored complex with iron that can be measured spectrophotometrically?

A. Bathophenanthroline
B. 8-Hydroxyquinoline
C. Tripyridyltriazine
D. Ferrozine

Question 27

In what disorder would an increased percent saturation of transferrin be expected?

A. Hemochromatosis
B. Iron-deficiency anemia
C. Myocardial infarction
D. Malignancy

Question 28

Which of the following disorders is best characterized by these laboratory results?

Serum iron—decreased
Total iron-binding capacity—increased
Transferrin saturation—decreased
Serum ferritin—decreased
Free erythrocyte protoporphyrin—increased

A. Anemia of chronic disease
B. Thalassemia
C. Iron-deficiency anemia
D. Hemochromatosis

Question 29

Which of the following is not a typical finding in magnesium deficiency tetany?

A. High serum phosphate level
B. Normal serum calcium level
C. Normal blood pH value
D. Low serum potassium level

Question 30

Which of the following constituents normally present in serum must be chemically eliminated so that it will not interfere with the measurement of serum magnesium?

A. Calcium
B. Chloride
C. Iron
D. Potassium

Question 31

In the collection of plasma specimens for lactate determinations, which of the following anticoagulants would be more appropriate?

A. Sodium heparin
B. Sodium citrate
C. EDTA
D. Oxalate plus fluoride

Question 32

Which of the following disorders is characterized by increased production of chloride in sweat?

A. Multiple myeloma
B. Hypoparathyroidism
C. Cystic fibrosis
D. Wilson disease

Question 33

Which of the following is not a colligative property of solutions?

A. pH
B. Freezing point
C. Osmotic pressure
D. Vapor pressure

Question 34

Which of the following describes the basis for the freezing point osmometer?

A. The freezing point depression is directly proportional to the amount of solvent present.
B. The freezing point depression varies as the logarithm of the concentration of solute.
C. The freezing point is raised by an amount that is inversely proportional to the concentration of dissolved particles in the solution.
D. The freezing point is lowered by an amount that is directly proportional to the concentration of dissolved particles in the solution.

Question 35

Given the following information, calculate the plasma osmolality in milliosmoles per kilogram: sodium—142 mmol/L; glucose—130 mg/dL; urea nitrogen— 18mg/dL.

A. 290
B. 291
C. 295
D. 298

Question 36

Which of the following may be associated with the colloid osmotic pressure (COP) osmometer?

A. Utilizes a cooling bath set at -7°C
B. Measures total serum osmolality
C. Negative pressure on reference (saline) side equivalent to COP of sample
D. Measures contribution of electrolytes to osmolality