Q: Which of the following is the correct formula for calculating the anion gap (without potassium)?

$$\text{Anion gap} = [\text{Na}^+] - ([\text{Cl}^-] + [\text{HCO}_3^-])$$

Question 1

Which process describes the movement of water across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration?

Accepted Answer

Osmosis

Question 2

A patient with severe burns develops edema due to fluid shifting from the vascular space into the interstitial space. Which term best describes this phenomenon?

Accepted Answer

Third-space fluid shift

Question 3

Which laboratory value is most reliable for assessing urine concentration?

Accepted Answer

Urine osmolality

Question 4

A patient presents with confusion, muscle weakness, and ECG changes showing flat T waves and a prominent U wave. Which electrolyte imbalance is most likely?

Accepted Answer

Hypokalemia

Question 5

Which hormone is released from the posterior pituitary gland in response to increased serum osmolality and acts to increase water reabsorption in the kidneys?

Accepted Answer

Antidiuretic hormone (ADH)

Question 6

A patient with heart failure is found to have distended jugular veins, crackles in the lungs, and pitting edema. Which fluid imbalance is most likely present?

Accepted Answer

Fluid volume excess (FVE)

Question 7

Which of the following best describes the effect of aldosterone on electrolyte balance?

Accepted Answer

Increases sodium and water retention, increases potassium loss

Question 8

A patient with chronic kidney disease is at risk for which electrolyte imbalance due to decreased phosphate excretion?

Accepted Answer

Hyperphosphatemia

Question 9

Which of the following is a characteristic of isotonic intravenous fluids?

Accepted Answer

Expand extracellular fluid volume without changing cell size

Question 10

A patient with a serum sodium of 128 mEq/L and a history of taking SSRIs is most likely experiencing which condition?

Accepted Answer

Hyponatremia

Question 11

Which of the following best explains why a patient with metabolic acidosis may develop hyperkalemia?

Accepted Answer

Hydrogen ions move into cells, causing potassium to move out

Question 12

A patient with a serum calcium of 7.8 mg/dL, positive Chvostek sign, and recent thyroid surgery is most likely experiencing which condition?

Accepted Answer

Hypocalcemia

Question 13

Which of the following is the correct formula for calculating the anion gap (without potassium)?

Accepted Answer

$$	ext{Anion gap} = [	ext{Na}^+] - ([	ext{Cl}^-] + [	ext{HCO}_3^-])$$

Question 14

A patient with a pH of 7.28, PaCO$$_2 of 50 mm Hg$$, and HCO$$_3^- of 24 $$mEq/L is most likely experiencing which acid–base disturbance?

Accepted Answer

Respiratory acidosis

Question 15

Which of the following best describes the effect of atrial natriuretic peptide (ANP) on fluid balance?

Accepted Answer

Promotes sodium excretion and opposes the renin–angiotensin–aldosterone system

Question 16

A patient with a serum magnesium of 3.2 mg/dL, hypotension, and respiratory depression is most likely experiencing which condition?

Accepted Answer

Hypermagnesemia

Question 17

Which of the following is a primary function of the kidneys in maintaining acid–base balance?

Accepted Answer

Regenerate and reabsorb bicarbonate ions

Question 18

A patient with a serum sodium of 150 mEq/L, dry mucous membranes, and restlessness should be treated with which type of intravenous solution?

Accepted Answer

Hypotonic solution (0.45% NaCl or D5W)

Question 19

Which of the following best explains why pure, electrolyte-free water is never administered intravenously?

Accepted Answer

It causes hemolysis of red blood cells due to osmotic imbalance

Fluid and Electrolyte Balance: Concepts, Regulation, and Clinical Implications

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