SEVERE, PROLONGED, DENOSUMAB-INDUCED HYPOCALCEMIA WITH RECOVERY AFTER 111 DAYS OF HIGH-DOSE CALCIUM SUPPLEMENTATION

Severe hypocalcemia after denosumab treatment leading to refractory ventricular tachycardia and veno-arterial extracorporeal membrane oxygenation support: a case report

BACKGROUND

Severe hypocalcemia may lead to life-threatening arrhythmias. Denosumab is an effective treatment for osteoporosis that allows long intervals between doses. However, there is a risk of hypocalcemia in some patients. Due to the long half-life of denosumab, emergency physicians caring for patients presenting with symptoms of hypocalcemia may not be aware of the medication, and adverse effects may last longer.

CASE PRESENTATION

A 55-year-old woman with a history of systemic lupus erythematosus (SLE) and anxiety disorder called for an ambulance for symptoms of hyperventilation and muscle cramps. After evaluation at the local hospital, she developed pulseless ventricular tachycardia and was resuscitated by defibrillation by the hospital staff. After conversion to sinus rhythm, she was transported to a tertiary center. Upon arrival, pulseless ventricular tachycardia occurred again, and veno-arterial extracorporeal membrane oxygenation (ECMO) and intra-aortic balloon pumping (IABP) were implemented. Laboratory results showed severe hypocalcemia (corrected calcium level of 5.3 mg/dL) whereupon intravenous calcium supplementation was started. She had received the first dose of denosumab (60 mg) by subcutaneous injection 24 days prior to hospitalization. She was eventually weaned from ECMO and IABP support.

CONCLUSION

Cardiac arrest due to hypocalcemia is relatively rare but can be fatal. In the present case, hyperventilation may have acutely exacerbated pre-existing hypocalcemia, leading to ventricular tachycardia. The patient had a slightly decreased serum calcium level prior to denosumab. Close monitoring may be preferable after the primary dose of denosumab in selected patients. Emergency physicians caring for patients who may be suffering from symptoms/signs of hypocalcemia must be mindful of medications that have long half-lives and affect electrolyte balance when treating fatal arrhythmia due to hypocalcemia.

Severe Refractory Hypocalcemia Caused by Denosumab

Denosumab is a fully human monoclonal antibody that binds to the receptor activator of nuclear factor kappa-Β ligand, an essential cytokine factor in bone resorption, which reduces bone resorption and has been shown to decrease the incidence of skeletal-related events in patients with malignancy and bone metastasis. Severe hypocalcemia is a rare and life-threatening adverse effect of denosumab therapy. Here, we discuss the case of a patient with stage 4 estrogen receptor-positive, progesterone receptor-negative, human epidermal growth factor receptor 2-negative breast cancer who was on treatment with denosumab for bony metastases and presented with severe refractory hypocalcemia.

Hungry bone syndrome like presentation following single-dose denosumab for hypercalcaemia secondary to sarcoidosis with IgA nephropathy

A woman in her mid-50s with IgA nephropathy, sarcoidosis and steroid-induced diabetes mellitus presented with generalised paraesthesia and spontaneous tetany. She had received denosumab 60 mg subcutaneously 8 weeks previously for parathyroid hormone independent hypercalcaemia.At admission, she had severe hypocalcaemia (5 mg/dL), hypophosphataemia (1.9 mg/dL), hypomagnesaemia (1.4 mg/dL) and elevated serum creatinine (1.48 mg/dL) with prolonged QTc (corrected QT interval) on electrocardiograph. She initially received intravenous calcium and magnesium followed by oral calcium carbonate and calcitriol. Her prednisolone dose was tapered to 5 mg/day. Evaluation showed secondary hyperparathyroidism (1474 pg/mL) and elevated 1,25-dihydroxy vitamin D (195 pg/mL). After 1 week of oral calcium carbonate (3000 mg/day) and calcitriol (1.5 µg/day), she achieved normocalcaemia (8.1 mg/dL).To conclude, denosumab for hypercalcaemia with renal insufficiency causes prolonged severe symptomatic hypocalcaemia and hypophosphataemia mimicking hungry bone syndrome. It is important to periodically monitor for hypocalcaemia after denosumab.

Severe and refractory hypocalcaemia secondary to osteoblastic bone metastases in bladder signet ring carcinoma: A case report and literature review

RATIONALE

Symptomatic hypocalcaemia is uncommon, occurring in <2% of patients with malignancy. Osteoblastic bone metastasis as a cause of hypocalcaemia is rare and not reported in bladder cancer.

PATIENT CONCERNS

We report a case of refractory hypocalcaemia in a patient with bladder cancer with extensive osteoblastic bone metastases. A 64-year-old male with a history of signet ring bladder carcinoma with osteoblastic bone metastases presented with severe hypocalcaemia with corrected calcium of 1.64 (2.09-2.46) mmol/L as well as hypomagnesemia and hypophosphatemia. He was previously treated with chemotherapy and immunotherapy. Denosumab was also initiated for the prevention of skeletal-related events.

DIAGNOSES

Additional investigations showed significantly elevated bone formation markers N-terminal propeptide of type I procollagen and alkaline phosphatase. Chest radiography and computed tomography scan also demonstrated extensive areas of sclerotic bone lesions suggestive of osteoblastic bone metastases. He was diagnosed with severe hypocalcaemia secondary to osteoblastic bone metastases and partly to denosumab, vitamin D deficiency, and hypomagnesemia.

INTERVENTIONS

He was treated aggressively with calcium and vitamin D replacement.

OUTCOMES

Despite prolonged intravenous calcium replacement and high doses of oral calcium, cholecalciferol, and calcitriol replacement, he had persistent hypocalcaemia with calcium levels ranging from 1.8 to 1.9 mmol/L. He died 4 months after his admission.

LESSONS

Osteoblastic bone metastases lead to an increased influx of calcium and phosphate into the bone leading to hypocalcaemia and should be considered as a differential in severe and refractory hypocalcaemia. It is rare and has not been described in bladder cancer. Precaution should be taken upon the initiation of antiresorptive in patients with osteoblastic bone metastases.

Hypocalcaemia following denosumab in prostate cancer: A clinical review

OBJECTIVES

Denosumab is often used in men with advanced prostate cancer to prevent skeletal-related events, but can be associated with severe hypocalcaemia. Our objective was to review the pathophysiology, identify risk factors and provide recommendations for prevention and management of denosumab-associated hypocalcaemia.

DESIGN

We reviewed the literature regarding denosumab-associated severe hypocalcaemia, defined as necessitating hospitalization for intravenous calcium treatment, in the context of prostate cancer.

PATIENTS

Men with prostate cancer with severe denosumab-associated hypocalcemia.

RESULTS

We identified 20 men with prostate cancer with severe denosumab-associated hypocalcemia, including the present case. Median age (range) was 70 years (45-86). All had skeletal metastases and presented with symptomatic hypocalcemia 16 days (4-35) after the initial (n = 18) or second (n = 2) denosumab treatment, with a serum total calcium of 1.36 mmol/L (1.13-1.91). The key risk factor was presence of active osteoblastic metastases, evidenced by elevated serum alkaline phosphatase, 838 U/L (58-2620) and supportive imaging. Other risk factors reported in some men included vitamin D deficiency (<50 nmol/L), 25-OH vitamin D 44 nmol/L (22-81), renal impairment, serum creatinine 103 μmol/L (62-1131) and hypomagnesaemia, 0.82 mmol/L (0.29-1.20). Men received intravenous calcium infusions for 16 days (1-90), and median total intravenous elemental calcium requirements were 3.17 g (0.47-26.65).

CONCLUSIONS

Denosumab treatment in men with metastatic prostate cancer can be associated with life-threatening hypocalcaemia requiring prolonged hospitalization for intravenous calcium treatment. Modifiable risk factors should be corrected before denosumab administration. In men with active osteoblastic metastases, consideration should be given to delay denosumab treatment until underlying disease activity is controlled, and/or be administered with close monitoring and proactive treatment with calcium and calcitriol.