History of present illness: A 65-year-old white woman with stage IIIC papillary serous ovarian carcinoma presents with complaints of numbness and muscle cramps. She is currently undergoing chemotherapy with paclitaxel and carboplatin. She completed her fourth cycle three days ago. For the past two days, she has noted numbness around her mouth and a tingling sensation in her hands and feet. Last night, she was unable to sleep due to cramps in her legs. She reports that she has never had symptoms like this before, and she is anxious about what could be causing them. Her past medical history is significant only for mild hypertension and hyperlipidemia, for which she takes hydrochlorothiazide 25 mg daily and atorvastatin 40 mg nightly. Her other home medications include a daily multivitamin and hydrocodone/acetaminophen 5 mg/325 mg as needed for pain. Physical examination General appearance: Well-developed white woman in no acute distress Vital signs: Temperature: 98.3°C Pulse: 71 beats/min Blood pressure: 134/82 mmHg Respiratory rate: 14 breaths/min BMI: 24 kg/m2Neurologic: Alert and oriented to person, place, time, and situation; 5/5 strength in all extremities; decreased sensation to pinprick, temperature, and vibration in distal extremities. Twitching of the left side of the mouth elicited by tapping just anterior to the patient’s left ear. When a blood pressure cuff was inflated to 160 mmHg and left in place, flexion of the wrist and metacarpophalangeal joints, as well as extension and adduction of the fingers, were noted Laboratory studies: Serum calcium: 6.3 mg/dL (normal 8.4–10.2 mg/dL) Ionized calcium: 3.8 mg/dL (normal 4.4–5.3 mg/dL) Serum magnesium: 1.3 mg/dL (normal 1.8–2.5 mg/dL) Serum albumin: 2.9 g/dL (normal 3.4–5.0 g/dL) The remainder of her basic metabolic panel, CBC, and hepatic function panel were within normal limits Imaging: ECG showed a prolonged QT interval.