ATI TEAS (Test of Essential Academic Skills) Version 7ScienceHard
A patient presents with symptoms including an irregular heartbeat, muscle cramps, and general weakness. Blood tests reveal an electrolyte imbalance, specifically low levels of a cation crucial for nerve impulse transmission and muscle contraction. Which electrolyte is most likely deficient?
- APotassium (K+)
- BSodium (Na+)
- CCalcium (Ca2+)
- DMagnesium (Mg2+)
Show answer & explanationAnswer & explanation
Correct answer: A. Potassium (K+)
Potassium (K+) is a critical intracellular cation involved in maintaining resting membrane potential, nerve impulse transmission, and muscle contraction. Low levels (hypokalemia) commonly manifest as cardiac arrhythmias (irregular heartbeat), muscle weakness, and cramps.
Why the other options are wrong
- B. Sodium (Na+) is key for fluid balance and nerve impulses, but its deficiency (hyponatremia) typically causes confusion, seizures, and cerebral edema, not primarily irregular heartbeat or muscle cramps.
- C. Calcium (Ca2+) is vital for muscle contraction, bone health, and nerve function; low levels (hypocalcemia) cause tetany, numbness, and tingling, but irregular heartbeat is less specific than with potassium.
- D. Magnesium (Mg2+) is important for enzyme function and nerve/muscle function; low levels (hypomagnesemia) can cause tremors, seizures, and arrhythmias, but potassium is a more direct fit for the specific symptom combination.
Potassium (K+)
A major intracellular cation essential for maintaining cell membrane potential, nerve impulse transmission, muscle contraction (especially cardiac muscle), and fluid balance.
- Regulated by the kidneys.
- Imbalances (hypokalemia/hyperkalemia) can severely affect heart rhythm.
- Plays a crucial role in the repolarization phase of action potentials.
Memory trick: K for Kramp, K for Kardiak Rhythm.