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. ).
A 74-year-old male with a past medical history of severe osteoporosis, chronic obstructive pulmonary disease (COPD), marginal gastric ulcers status-post sleeve gastrectomy, and Crohn’s disease status-post small bowel resection presented to the emergency department due to an acute onset of right shoulder pain. Vital signs revealed a temperature of 37.2°C, blood pressure of 112/61 mmHg, heart rate of 78, respiratory rate of 16 and oxygen saturation of 92% on 1.5 L by nasal cannula, which he used at baseline. Initial laboratory workup revealed severe hypocalcemia at 4.8 mg/dL and hypophosphatemia at 0.8 mg/dL. Upon further history taking, the patient stated that he receives denosumab injections for his severe osteoporosis. The patient denied muscle cramps, spasms, weakness, seizures, facial twitching, lightheadedness, and psychiatric changes. Of note, he had a history of chronic hypocalcemia with a baseline of 7 mg/dL and reported taking daily calcium and vitamin D supplements. His physical examination was unremarkable except for shoulder pain on passive range of motion. Chvostek and Trousseau signs were both negative. Additional laboratory workup (Table ) was significant for hyperparathyroidism and normal levels of magnesium, albumin, and vitamin D. His arterial blood gas results (Table ) revealed respiratory acidosis presumed to be due to COPD.\nThe patient was admitted to the intensive care unit, monitored on cardiac telemetry, and started on IV calcium carbonate in addition to his home calcium and vitamin D oral supplements. Endocrinology was consulted and calcium levels were trended until normalization. The patient was ultimately discharged on calcium carbonate 1,250 mg by mouth three times per day, calcium-vitamin D gummies by mouth three times per day, cholecalciferol 1,000 international units by mouth two times per day, and calcitriol 0.5 mcg oral capsule four times per day. His serum calcium level at eight months post-discharge has been maintained at roughly 9.5 mg/dL on this regimen and he has remained asymptomatic throughout.