Deck 36: Potassium, calcium, and Phosphate Homeostasis

Question 1

Which of the following enhances urinary K⁺ excretion?

A)Osmotic diuresis
B)Acute metabolic acidosis
C)Hypoaldosteronism
D)Decreased tubular flow rate
E)Water diuresis

Answer 1

A

Question 2

Hyperkalemia is most likely to occur in which of the following conditions?

A)Metabolic alkalosis
B)Exercise
C)Insulin injection
D)Decreased plasma osmolality
E)Administration of a $\beta$ -adrenergic agonist

Answer 2

Exercise

Question 3

A 45-year-old man is prescribed an angiotensin-converting enzyme inhibitor as part of his therapy for hypertension.If he does not change his diet,what changes in his serum [Na⁺] and serum [K⁺] would you expect?

Answer 3

B

Question 4

A 65-year-old man has chronic renal failure.What are the expected changes in his serum Ca⁺⁺,inorganic phosphate (P_i),and calcitriol levels? (Note: Changes are those expected in comparison with the values in an individual with normal renal function.)

Question 5

A 21-year-old man with insulin-dependent (type 1)diabetes mellitus who forgot to inject his insulin is seen in the emergency department.The following laboratory data are obtained: Serum [Na⁺] = 140 mEq/L (normal: 135 to 147 mEq/L)
Serum [K⁺] = 6.5 mEq/L (normal: 3.5 to 5.0 mEq/L)
Serum [HCO₃^-] = 10 mEq/L (normal: 22 to 28 mEq/L)
Blood pH = 7.0 (normal: 7.35 to 7.45)
Arterial partial pressure of carbon dioxide (Pco₂)= 25 mm Hg (normal: 33 to 44 mm Hg)
Serum glucose concentration = 1000 mg/dL (normal: 70 to 110 mg/dL)
Which of the following plays the most important role in the generation of hyperkalemia in this man?

A)Low plasma osmolality
B)Low arterial Pco₂
C)Hyponatremia
D)Metabolic acidosis
E)Low plasma insulin concentration

Question 6

Which of the following conditions would be expected to reduce the free (i.e.,ionized)[Ca⁺⁺] in the plasma?

A)Metabolic acidosis
B)Reduced dietary intake of phosphate
C)A tumor secreting parathyroid hormone-like peptide
D)Ingestion of calcitriol
E)Acute respiratory alkalosis

Question 7

Urinary K⁺ excretion is increased by which of the following?

A)Hypokalemia
B)Hyperaldosteronism
C)Antidiuretic hormone (ADH)
D)A decrease in glomerular filtration rate (GFR)
E)Administration of amiloride

Question 8

A healthy individual,weighing 60 kg,receives an infusion of 1 L of isotonic saline to which 20 mEq of K⁺ has been added.After the infusion,the plasma [K⁺] of this individual has increased from 3.5 mEq/L to 7.8 mEq/L.What is the most plausible explanation for the development of hyperkalemia in this individual?

A)K⁺ shifts from the intracellular fluid (ICF)into the extracellular fluid (ECF).
B)Renal excretion of K⁺ is impaired.
C)The increase in plasma [K⁺] of 4.3 mEq/L is what is expected from the addition of 20 mEq/L of K⁺ to the ECF.
D)The ECF volume contracts.
E)Hyperosmolality develops.

Question 9

Which of the following hormones plays an important role in keeping the plasma concentration of K⁺ within normal limits?

A)Calcitriol
B)Vasopressin
C)Parathyroid hormone (PTH)
D)Insulin
E)Glucagon