Off-Label Use of Denosumab in the Treatment of Hypercalcemia from Primary Hyperparathyroidism

Presentation Number: MON 300
Date of Presentation: April 3rd, 2017

Sana Akbar*1, Preethi Kadambi1 and Nicole M Ehrhardt2
1GWU, Washington, DC, 2George Washington University School of Medicine and Health Sciences, Washington, DC

Abstract

Introduction:

Denosumab is a monoclonal antibody commonly used in the treatment of osteoporosis but also approved for use in hypercalcemia of malignancy (HCM). It has been shown to significantly reduce calcium levels. However, only one previous case has reported on its use in primary hyperparathyroidism (PHPT). Here we report another case of Denosumab use for hypercalcemia secondary to PHPT.

Case:

An 87 year old Caucasian woman with history of hypertension, coronary artery disease, chronic kidney disease (CKD) stage 3, hypothyroidism, osteoarthritis and PHPT was admitted for worsening hypercalcemia. Patient had previously been started on Cinacalcet as she was felt to be a poor surgical candidate given age, co-morbidities and possible ectopic location of her parathyroid adenoma. However, Cinacalcet had then been stopped given worsening abdominal pain that improved with cessation of medication.

On admission, she had a corrected calcium level of 13.5 mg/dL (normal 8.7-10.3 mg/dL), ionized calcium of 8.2 mg/dL (4.5-5.6 mg/dL), albumin of 4.4 g/dL (normal 3.5-4.7 g/dL), PTH of 183 pg/mL (15-65 pg/mL), creatinine of 2.0 mg/dL (normal 0.57-1.0 mg/dL), and eGFR of 22 mL/min (normal > 59 mL/min). She received IV hydration with some improvement. As she was not a candidate for bisphosphonate therapy given eGFR<30, she was given Denosumab 120 mg subcutaneously. Her corrected calcium of 11.68 mg/dL improved to 10.24 mg/dL, and ionized calcium normalized at 5.6 mg/dL within 24 hours of treatment. Three months post Denosumab, her corrected calcium remained in the normal reference range at 9.7 mg/dL.

Conclusion:

Use of Denosumab in the setting of PHPT may provide long term calcium improvement with minimal side-effects and should be considered in PHPT patients when bisphosphonates are contraindicated and who are intolerant to Cinacalcet.

 

Nothing to Disclose: SA, PK, NME