Fluid and Electrolytes Quiz
Questions: 16 · 10 minutes
1. A patient has marked hyponatremia and new confusion. Which immediate physiological problem is most closely associated with the low sodium concentration?
Water leaves brain cells because extracellular fluid is hypertonic
Calcium deposits rapidly form inside brain tissue
Red blood cells produce excess sodium to restore plasma levels
Water moves into brain cells, contributing to cerebral swelling
2. Which electrolyte is the principal positively charged ion in extracellular fluid?
Potassium
Sodium
Magnesium
Phosphate
3. Following heavy sweating without adequate fluid replacement, which kidney response would best help conserve water?
Producing a large volume of very dilute urine
Reducing water reabsorption in the collecting ducts
Excreting extra sodium and water regardless of blood volume
Producing a smaller volume of more concentrated urine
4. After neck surgery, a patient develops tingling around the mouth and painful muscle spasms. Which electrolyte disturbance is most consistent with these findings?
Hypernatremia
Hypocalcemia
Hypercalcemia
Hyperchloremia
5. When hypernatremia results mainly from free-water loss, what happens to cells as extracellular fluid becomes more concentrated?
Water leaves cells, causing them to shrink
Cells absorb water and swell because extracellular osmolality falls
Sodium rapidly enters cells and draws water with it
Cell volume remains unchanged because sodium cannot cross membranes freely
6. A patient taking a potassium-wasting diuretic develops weakness. Which combination would most strongly support hypokalemia?
Elevated serum potassium with peaked T waves
Elevated serum calcium with widened pulse pressure
Low serum sodium with a shortened QT interval
Low serum potassium with flattened T waves and prominent U waves
7. Which hormone promotes sodium reabsorption while increasing potassium secretion in the distal nephron?
Atrial natriuretic peptide
Parathyroid hormone
Aldosterone
Calcitonin
8. What is the primary effect of antidiuretic hormone, also called ADH or vasopressin, on the kidneys?
It increases sodium loss while leaving water handling unchanged
It directly increases potassium secretion from every nephron segment
It increases water reabsorption and helps concentrate urine
It prevents water from moving between intracellular and extracellular fluid
9. Which ECG change is classically associated with hyperkalemia, particularly as potassium rises?
Tall, peaked T waves
Prominent U waves with flattened T waves
A consistently shortened PR interval as the only change
Electrical alternans caused by pericardial fluid
10. A patient with diabetic ketoacidosis begins insulin treatment. Why must serum potassium be monitored closely even if the initial potassium level was not low?
Insulin shifts potassium into cells, which can lower the serum concentration
Insulin releases stored potassium from bone into plasma
Insulin prevents potassium from entering skeletal muscle
Insulin blocks potassium filtration by the kidneys
11. A person with significant kidney impairment regularly uses a magnesium-containing antacid and develops lethargy, weakness, and reduced deep-tendon reflexes. Which imbalance is most likely?
Hypermagnesemia
Hypercalcemia
Hypomagnesemia
Hypophosphatemia
12. After infusion, where does isotonic 0.9% sodium chloride primarily add volume?
The intracellular fluid compartment only
The extracellular fluid compartment
Total body water equally, with most entering cells
Bone and connective tissue without affecting plasma volume
13. Which statement best describes osmosis across a semipermeable cell membrane?
Charged solutes move against their concentration gradient without energy
Proteins move from plasma into cells until their concentrations match
Water moves toward the side with the higher effective solute concentration
Water and all dissolved particles cross the membrane at identical rates
14. A patient with very low plasma albumin develops ankle edema. Which mechanism best explains the fluid shift?
Increased plasma oncotic pressure pulls excess water into capillaries
Reduced plasma oncotic pressure allows more fluid to remain in interstitial tissue
Reduced intracellular potassium forces water out through the skin
Increased ADH directly moves plasma proteins into the urine
15. A person has had persistent vomiting for several days. Which acid-base and electrolyte pattern is most directly associated with losing gastric fluid?
Respiratory acidosis caused by bicarbonate loss
Non-anion-gap metabolic acidosis with increased chloride
Metabolic alkalosis with chloride depletion
High-anion-gap metabolic acidosis caused by phosphate loss
16. A patient develops frequent watery diarrhea. Which disturbance can result directly from substantial bicarbonate loss in stool?
Metabolic alkalosis
Respiratory acidosis
Respiratory alkalosis
Non-anion-gap metabolic acidosis