A 24-year-old female with a past medical history of depression, anxiety, and cannabis use presented to the emergency department with a complaint of lower extremity weakness of two days duration. She first noticed the weakness following a mechanical fall, with no loss of consciousness, no syncope, and no injury. The weakness progressed to a point where she could no longer ambulate. She reported palpitations and myalgias (particularly in the medial aspects of both legs), but denied fever, chills, nausea, vomiting, dizziness, lightheadedness, headaches, recent changes to activity, changes to medications or diet, intake of high carbohydrate meals, and any previous instances of weakness.

The patient’s active medications included 100 mg of oral bupropion daily, 20 mg of oral escitalopram daily, 20 mg of oral propranolol as needed, and an oral, daily two-hormone contraceptive. Although the patient had no remarkable family history or allergies, her social history was significant for intermittent tobacco use, alongside daily cannabis use via vaporizer pen since age 18. Of note, the patient reported finishing one vaporizer cartridge per day; when asked about product usage guidelines, the patient disclosed that each cartridge should last approximately three months with expected, moderate use.

Initial physical exam revealed normal heart rate and heart sounds; cranial nerves were intact; bilateral 1/5 strength for dorsiflexion of ankles, 5/5 strength for ankle plantarflexion, hip flexion, and knee flexion; intact sensation to the lower extremities; and palpable distal pulses. Ankle deep tendon reflexes (DTR) were not tested, as the patient’s feet were significantly plantarflexed at rest. Passive movement of the ankles demonstrated no resistance. DTR of bilateral knees were +1. Initial vital signs included a heart rate of 60 beats per minute, blood pressure of 121/86, respiratory rate of 14, oxygen saturation of 94%, and oral temperature of 98.7℉. The patient’s body mass index (BMI) was 36.12.

Initial laboratory results were remarkable for a potassium value of 1.8, with stable magnesium and calcium (Table 1). An electrocardiogram (EKG) was obtained, revealing sinus bradycardia with a prolonged corrected QT (QTc) interval of 628 milliseconds, as measured by Fridericia’s formula (Figure 1). The patient was given 40 milliequivalents (mEq) of oral potassium and 10 mEq of intravenous (IV) potassium. One gram of oral magnesium was also provided for cardiac membrane stabilization. The patient’s escitalopram and propranolol were placed on hold, given her prolonged QTc interval and bradycardia, respectively. She was then promptly transferred to the intensive care unit for close cardiac and electrolyte monitoring.

Following transfer and extensive fluid administration, the patient was also found to have a phosphorus value of 1.0, prompting IV repletion (Table 1). The remainder of the patient’s hospital stay was unremarkable. On day 2 of admission, renal studies found no increase in urine potassium or serum pH imbalance; thyroid panel was unremarkable; and electrolytes were stable throughout admission following hypokalemia correction (Table 2). The patient was transferred to a general medical floor with telemetry on day 3 of admission, where cardiac monitoring demonstrated normal sinus rhythm; she also had complete alleviation of weakness on the same day. On day 4, she was discharged with a final potassium value of 4.0 mmol/L and instructed to supplement with a 10 mEq oral potassium daily; she also had a follow-up appointment one week later at a nephrology clinic, with repeat laboratory work at which time her potassium value was 4.0 mmol/L.