A nurse is reviewing the laboratory report for a client who has been taking sodium polystyrene sulfonate.
Which of the following findings indicates a therapeutic response to the medication?
Magnesium 1.5 mEq/L (1.3 to 2.1 mEq/L).
Calcium 9.2 mg/dL (9 to 10.5 mg/dL).
Sodium 140 mEq/L (136 to 145 mEq/L).
Potassium 4.8 mEq/L (3.5 to 5 mEq/L).
The Correct Answer is D
Choice A rationale
Magnesium levels within the normal range (1.3 to 2.1 mEq/L) are important for overall electrolyte balance, but sodium polystyrene sulfonate specifically targets potassium. While hyperkalemia can sometimes be associated with other electrolyte imbalances, a normal magnesium level does not directly indicate a therapeutic response to sodium polystyrene sulfonate, as its primary action is not on magnesium.
Choice B rationale
Calcium levels within the normal range (9 to 10.5 mg/dL) are essential for various physiological functions. Sodium polystyrene sulfonate primarily exchanges sodium ions for potassium ions, not calcium. Therefore, a normal calcium level does not reflect a therapeutic response to the medication, which is specifically aimed at reducing elevated potassium levels.
Choice C rationale
Sodium levels within the normal range (136 to 145 mEq/L) are crucial for fluid balance and neurological function. Sodium polystyrene sulfonate exchanges sodium for potassium, meaning it increases the body's sodium load. While a normal sodium level is desirable, it does not directly indicate the therapeutic efficacy of the medication in reducing potassium.
Choice D rationale
Potassium 4.8 mEq/L (3.5 to 5 mEq/L) indicates a therapeutic response. Sodium polystyrene sulfonate is an ion-exchange resin used to treat hyperkalemia by exchanging potassium ions for sodium ions in the gastrointestinal tract. A potassium level returning to within the normal range, from a previously elevated state, signifies that the medication has effectively lowered the excess potassium.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
Choice A rationale
Cromolyn is a mast cell stabilizer that works by inhibiting the release of inflammatory mediators like histamine from mast cells. This prophylactic action requires consistent, daily use to build up therapeutic levels and prevent the initiation of the asthmatic response, rather than acting as a rescue medication during an acute attack.
Choice B rationale
Using cromolyn as soon as one feels like wheezing is incorrect because cromolyn is not a bronchodilator and does not provide immediate relief for acute bronchospasm. Its mechanism of action involves stabilizing mast cells, which prevents the degranulation and release of inflammatory mediators, thus preventing symptoms from occurring.
Choice C rationale
Expecting to feel better in a week is an inappropriate timeframe for assessing cromolyn's efficacy. The full prophylactic benefits of cromolyn may take several weeks of consistent use to become apparent. Patients should be educated on the preventative nature and delayed onset of action.
Choice D rationale
While cromolyn can be used prophylactically before exercise, using it 2 hours before playing softball is not the recommended timing. For exercise-induced bronchospasm, cromolyn is typically administered 15 to 30 minutes prior to the activity to allow for adequate absorption and mast cell stabilization before exertion.
Correct Answer is C
Explanation
Choice A rationale
Sodium bicarbonate is used to treat metabolic acidosis or certain drug overdoses, but it does not directly address hypocalcemia, which is the underlying cause of a positive Trousseau's sign. Its primary action is to increase systemic pH, not calcium levels.
Choice B rationale
Magnesium sulfate is administered for magnesium deficiencies, pre-eclampsia, or certain arrhythmias. While magnesium deficiency can sometimes exacerbate hypocalcemia, it is not the primary treatment for Trousseau's sign, which specifically indicates low calcium.
Choice C rationale
Calcium gluconate is the appropriate medication to administer for a positive Trousseau's sign, as this sign indicates hypocalcemia (low serum calcium levels). Calcium gluconate directly replenishes calcium, correcting the neuromuscular excitability caused by insufficient extracellular calcium.
Choice D rationale
Potassium chloride is given to treat hypokalemia (low potassium levels). While electrolyte imbalances can be complex, a positive Trousseau's sign is specifically indicative of hypocalcemia, not hypokalemia, and potassium administration would not resolve the underlying issue.
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