A 59-year-old postmenopausal woman with a past medical history of Billroth II gastric bypass surgery 15 years before for bariatric purposes, Barrett esophagus, pericarditis secondary to suspected rheumatologic disease status treated with a pericardial window 3 years before, rheumatoid arthritis with negative rheumatoid factor, paroxysmal atrial fibrillation, amiodarone-induced hypothyroidism, and osteoporosis treated with denosumab 3 months before was referred to the emergency department by her endocrinologist after outpatient labs revealed profound hypocalcemia, hypophosphatemia, and hypomagnesemia. The patient had recently returned from vacation, where she experienced 2-3 episodes of diarrhea. She reported compliance to her medications, which included 50,000 IU ergocalciferol daily and 630 mg calcium citrate 2-3 times daily, apart from taking a decreased dose of calcium for the last 4 days of her vacation since she was running low on pills. She noted fatigue and intermittent tingling in her hands, feet, and perioral region for 2-3 days prior to admission. She denied weight loss, fever, muscle cramping, seizures, loss of consciousness, or lightheadedness.\nOn presentation, the patient was afebrile with a temperature of 98.2ºF, blood pressure of 136/74 mmHg, heart rate of 71 beats/min, and respiratory rate of 15 breaths/min. Her oxygen saturation was 100% on room air. Physical examination revealed a well-appearing woman with a body mass index (BMI) of 30 kg/m2 in no acute distress. Neck was supple with no thyromegaly. There were no abnormalities on cardiac or pulmonary exam. Abdomen was soft, nontender, and nondistended with normal bowel sounds. Patient had a positive Chvostek's sign. No muscle twitches or spasms were appreciated. Strength, sensation, reflexes, and cranial nerves were intact. The patient had no signs of confusion or psychosis.\nBlood tests from the emergency department revealed a calcium of 5.8 mg/dL, phosphorus of <1 mg/dL, and magnesium of 1.7 mg/dL. Albumin was 3.8 g/dL, so the corrected calcium was 6.0 mg/dL. Ionized calcium was 0.8 mg/dL. Parathyroid hormone was 136 ng/L. 25-Hydroxy vitamin D was normal at 46 ng/mL, and 1-25-hydroxy vitamin D was normal at 30 pg/mL. Urinalysis was within normal limits, and urine calcium was <2 mg/dL. Creatinine was 0.61 mg/dL, and blood urea nitrogen was 11 mg/dL. TSH was normal at 0.78 μU/mL. An electrocardiogram performed in the emergency department showed normal sinus rhythm with a corrected QT interval of 493 ms.\nIn the emergency department, the patient was given 2 g of IV magnesium sulfate, 30 mmol of IV sodium phosphate, and 1 g of IV calcium gluconate. During her 4-day hospital stay, the patient continued to receive IV calcium, as well as oral calcitriol, phosphate, and magnesium. When she was able to consistently maintain serum calcium of at least 8.0 mg/dL on oral calcium citrate supplementation, she was discharged with a calcium level of 8.0 mg/dL, magnesium of 1.9 mg/dL, and phosphorus of 2.3 mg/dL. She was instructed to take calcium citrate of 1260 mg 4 times daily, calcitriol of 0.25 mcg 2 times daily, phosphorus of 250 mg 3 times daily, and magnesium oxide of 400 mg 2 times daily and to be followed up closely with her endocrinologist. Since discharge, the patient has been able to maintain adequate calcium levels on a low dose of calcium supplementation, and she is interested in considering further doses of denosumab.
Patient 1 is an 80-year-old woman with stage 3B chronic kidney disease (CKD) who received an inadvertent dose of denosumab 1 month after her regularly scheduled dose. Eighteen days following the second dose, the patient presented to the emergency department with severe weakness that prevented her from getting out of bed. She denied seizures, syncope, chest pain, or palpitations. Neurological exam revealed 4/5 strength in all extremities. Chvostek sign was absent. Chemistries revealed a serum total calcium of 4.2 mg/dL, magnesium 1.2 mg/dL, phosphorous 2.4 mg/dL, ionized calcium 0.56 mmol/L (normal 1.11–1.3 mmol/L), 25-hydroxy vitamin D 11.0 ng/mL (normal 30–100 ng/mL), and intact PTH was >3,639 pg/mL (normal 14–60 pg/mL). Her eGFR on admission was 31 mL/min/1.72m2, and her serum creatinine was 1.9 mg/dL (baseline between 1.5 and 2 mg/dL). Two months prior to admission she had a serum calcium of 9.2 mg/dL. ECG revealed prolonged QT interval of 479 ms and prominent T waves. These two changes caused the automated interpretation of the ECG to indicate a heart rate 133/min, while her clinicians interpreted the heart rate to be 75 (Fig. ).