Physiology and Disorders of Water, Electrolyte, and Acid-Base Metabolism

Question 1

1. Total body water (TBW) makes up approximately 60%
   of adult body weight. The majority of TBW is
   located in which one of the following compartments?

a. Extracellular fluid (ECF)
b. Intracellular fluid (ICF)
c. Interstitial fluid
d. Plasma

Answer 1

b. Intracellular fluid (ICF)

Question 2

2. The anion gap, an estimate of anions not directly measured in serum, is correctly calculated by which one of
   the following formulae?

a. (Na) + (Cl + HCO3)
b. (Na) − (Cl + HCO3)
c. (Cl) + (HCO3 + Na)
d. (HCO3 − Na) − (Cl)

Answer 2

b. (Na) − (Cl + HCO3)

Question 3

3. Hypernatremia commonly occurs in:

a. decreased production of antidiuretic hormone
(ADH).
b. decreased aldosterone.
c. the syndrome of inappropriate ADH (SIADH)
secretion.
d. decreased cortisol.

Answer 3

a. decreased production of antidiuretic hormone
(ADH).

Question 4

4. A decrease in PCO2 and a resulting primary deficit in cdCO2 is referred to as

a. metabolic acidosis.
b. metabolic alkalosis.
c. respiratory acidosis.
d. respiratory alkalosis.

Answer 4

d. respiratory alkalosis

Question 5

5. Low blood volume will cause synthesis of this hormone
   by the kidneys, which in turn causes production of aldosterone, which will increase kidney reabsorption of
   sodium and retention of water.

a. Insulin
b. Renin
c. Antidiuretic hormone (ADH)
d. Erythropoietin

Answer 5

b. Renin

Question 6

6. The use of spironolactone in addition to an increased
   dietary intake of this particular electrolyte can lead to
   this disorder characterized by mental confusion, bradycardia, and possible eventual cardiac arrest.

a. Sodium; hypernatremia
b. Sodium; hyponatremia
c. Potassium; hyperkalemia
d. Potassium; hypokalemia

Answer 6

c. Potassium; hyperkalemia

Question 7

7. Which one of the following is the primary cause of respiratory acidosis?

a. Hyperventilation
b. Overdose of antacids
c. Chronic obstructive pulmonary disease (COPD)
d. Uncontrolled diabetes mellitus

Answer 7

c. Chronic obstructive pulmonary disease (COPD)

Question 8

8. Respiratory compensation of a metabolic alkalosis
   involves hypoventilation to increase PCO2. Which of the
   following is the maximum PCO2 achievable, and what
   limits PCO2 from increasing beyond that threshold?

a. 55 mm Hg, hypoxia
b. 65 mm Hg, CO2 solubility
c. 80 mm Hg, diffusion
d. 15 mm Hg, tetany/seizures

Answer 8

a. 55 mm Hg, hypoxia

Question 9

9. In the absence of an acid/base disorder, the normal ratio
   of bicarbonate to dissolved carbon dioxide in whole
   blood is approximately
   a. 10:1
   b. 1:20
   c. 20:1
   d. 1:10

Answer 9

c. 20:1

Question 10

10. Of the following causes of metabolic acidosis, which will
    present with an anion gap within the reference interval?
    a. Uremia of kidney failure
    b. Renal tubular acidosis type II
    c. D-Lactic acidosis
    d. Acetaminophen ingestion

Answer 10

b. Renal tubular acidosis type II