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

Accepted Answer

Osmotic diuresis enhances urinary K⁺ excretion by increasing the osmotic gradient in the renal tubules, which leads to increased water excretion and excretion of solutes, including K⁺.

Question 2

Hyperkalemia is most likely to occur in which of the following conditions?&#10;A)Metabolic alkalosis&#10;B)Exercise&#10;C)Insulin injection&#10;D)Decreased plasma osmolality&#10;E)Administration of a $\beta$-adrenergic agonist

Accepted Answer

Exercise can lead to hyperkalemia due to the release of potassium from muscle cells during physical activity.

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?

Accepted Answer

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.)

Accepted Answer

The answer of A 65-year-old man has chronic renal failure.What...

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

Accepted Answer

Insulin promotes cellular uptake of potassium, without insulin there is a shift of potassium out of cells and into the extracellular fluid, leading to hyperkalemia.

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

Accepted Answer

Acute respiratory alkalosis leads to an increase in blood pH (alkalosis), which causes calcium to bind more readily to albumin, thereby reducing the concentration of free (ionized) calcium in the plasma.

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

Accepted Answer

Hyperaldosteronism causes increased urinary excretion of potassium (K⁺). Aldosterone stimulates the distal tubule and collecting ducts in the kidney to increase potassium secretion and sodium reabsorption, thus leading to potassium excretion in the urine.

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.

Accepted Answer

The most plausible explanation for the hyperkalemia is option A, where K⁺ shifts from the intracellular fluid (ICF) into the extracellular fluid (ECF) due to the infusion of isotonic saline. This can lead to an increase in plasma [K⁺] and result in hyperkalemia. Options B, C, D, and E are not directly related to the development of hyperkalemia in this scenario.

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

Accepted Answer

Insulin helps regulate potassium levels by promoting the uptake of potassium into cells, thus playing a role in maintaining normal plasma potassium concentration.

Deck 36: Potassium, calcium, and Phosphate Homeostasis