Subcutaneous Paricalcitol for Severe Denosumab-induced Hypocalcemia

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SUN 234-256-Bone & Calcium Metabolism: Clinical Trials & Case Series
Sunday, June 16, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SUN-236
Nina Le*, David H Henry and Stephen G Rosen
Pennsylvania Hospital, Philadelphia, PA
Denosumab is contraindicated in patients with a history of hypocalcemia.  Severe renal impairment, history of hypoparathyroidism, previous parathyroid surgery, malabsorption, and small bowel resection may increase the risk of denosumab-induced hypocalcemia.   A 41-year-old woman with a history of tuberous sclerosis, hypertension, and gastroesophageal reflux disease underwent biliopancreatic diversion (BPD) for obesity in 2001.  Subsequently, she lost 190 kg.  Her medical course was complicated by a right hip fracture secondary to severe osteoporosis in 2003.  She was treated with large oral doses of calcium, vitamin D, and calcitriol.  She did not tolerate oral bisphosphonates, intravenous ibandronate, or intravenous zoledronic acid.   After sustaining additional fractures to her right femur and humerus as well as sacral compression fractures, she received denosumab with transient symptomatic hypocalcemia in November 2010.  After a second treatment with denosumab in October 2011, she was hospitalized with perioral paresthesias and tetany.  Laboratory testing revealed serum levels of total calcium (6.1 mg/dL; normal range 8.9-10.3 mg/dL), ionized calcium  (0.74 mM;  normal range 1.03-1.17 mM), intact PTH (314.9 pg/mL; normal range 12-72 pg/mL), 25-hydroxyvitamin D (21 ng/mL; normal range 30-80 ng/mL), and 1,25-dihydroxyvitamin D (42 pg/mL; normal range 15-75 pg/mL).  Her hypocalcemia was attributed to calcium and vitamin D malabsorption that was exacerbated by denosumab.  She was treated with intravenous calcium and intravenous paricalcitol daily in addition to oral calcium and vitamin D supplementation with symptomatic relief.  At discharge, her serum levels of total calcium (8.2 mg/dL) and ionized calcium (1.16 mM) were nearly normal.  She was discharged on her usual outpatient regimen in addition to weekly intravenous calcium gluconate and intravenous paricalcitol.  Despite this regimen, she required two subsequent hospital admissions for symptomatic hypocalcemia.  She was started on daily subcutaneous paricalcitol that resulted in decreased intravenous calcium requirements.  She was discharged on subcutaneous paricalcitol three times weekly in addition to lower doses of oral calcium and vitamin D.   Her serum levels of total calcium (8.1 mg/dL), ionized calcium (1.16 mM), and intact PTH (53 pg/mL) have been maintained.  Subcutaneous paricalcitol treatment was effective in correcting hypocalcemia in a patient with calcium and vitamin D malabsorption.

Nothing to Disclose: NL, DHH, SGR

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