A 42-year-old woman presents to the emergency department with severe muscle weakness and abdominal cramping which has been worsening over the past 3 days. She reports a history of hypertension and has been taking hydrochlorothiazide 50 mg daily for the past year. She also reports occasional use of a laxative for constipation and a daily vitamin D supplement. She denies use of any illicit substances. Vital signs are within normal limits and physical examination is unremarkable. Laboratory tests reveal hypokalemia with a potassium level of 2.5 mEq/L.
Which of the following is the most likely cause of this patient's hypokalemia?
The correct answer is:
B) Diuretic use
The patient's history of taking hydrochlorothiazide, a diuretic, for a prolonged period of time, combined with her symptoms of muscle weakness and abdominal cramping, suggest that the hypokalemia may be due to the diuretic causing the body to lose excess amounts of potassium through the urine.
Answer choice A: Adrenal insufficiency, is incorrect. The patient does not have other symptoms typically associated with adrenal insufficiency, such as fatigue and weight loss, and has normal vital signs which make it less likely that the hypokalemia is due to adrenal insufficiency. However, it is still a possibility and further testing may be needed to confirm or rule out this diagnosis.
Answer choice C: Excessive intake of laxatives, is incorrect. It is unlikely that the patient's hypokalemia is due to laxative abuse given her only intermittent use of a laxative.
Answer choice D: Excessive intake of vitamin D, is incorrect. Vitamin D does not directly cause hypokalemia.
Answer choice E: Inadequate intake of potassium, is incorrect. Inadequate intake of potassium alone is unlikely to cause hypokalemia in a patient taking a diuretic, as the diuretic would cause the body to lose excess potassium through the urine.
Key Learning Point
Hydrochlorothiazide can cause hypokalemia which can manifest with symptoms such as muscle weakness and abdominal cramping.
