SAT248 A Case Report Of Hypercalcemia Secondary To Calcium Sulfate Antibiotic Beads

Abstract

Abstract Disclosure: R. Habibi: None. G. Vahdani: None. N. Ebrahimi: None. Introduction: Periprosthetic joint infections are a rare and uncommon complication in arthroplasties of the hip or knee, happening in ∼0.7% of these procedures. Placement of antibiotic eluting beads, sometimes referred to as calcium sulfate beads (CSB), which are bio-compatible hydrophilic crystals used to deliver antibiotics locally, are one solution to prevent such complications. Hypercalcemia post-CSB placement is a very uncommon, rare and unusual complication that has only been presented in the literature a handful of times. Below, we report on a such a patient, illustrating the importance of surgical history in investigating the cause of hypercalcemia. Presentation: 63yo F with PMH of HTN, HLD, Crohn’s, T2DM, CKD3 who had a recent hospital admission 2 weeks prior for new arthritis secondary to pseudogout crystals, s/p bilateral synovectomy and CSB placement by orthopedics. She was subsequently discharged to nursing facility and re-presented to hospital for increasing AMS and worsening knee pain. Labs showed evidence of AKI with creatinine 1.9, severe hypercalcemia at 17.5 mg/dl with concomitant hypophosphatemia at 1.1 mg/dl. PTHrP WNL & PTH low at 7pg/ml and histo antigen neg, suggesting this was not related to PTH. Malignancy ruled out based on past imaging that was done in 2 months prior. MM ruled out since normal SPEP, UPEP, and kappa:lambda. Unlikely that this was milk alkali as patient did not have alkalosis. Vitamin 1,25 low at 10pg/ml ruling out sarcoidosis. Vitamin 25 WNL. Urine Ca 24hr WNL suggesting no FHH. Ca levels returned to normal after pamidronate, IV fluids and calcitonin. Chart review suggested that CSB implanted in her knees as the likely cause of her hypercalcemia. Discussion: It is important to bring awareness that one of the causes of severe hypercalcemia is post CSB placement. Vigilant monitoring of calcium levels pre and post operation after CSB placement is indicated, particularly in patients with a previous history of CKD. It has been hypothesized that there is a dose-dependent relationship between CSB volume and hypercalcemia, with suggestions that limiting CSB to less than 40ml per operation may be beneficial. A 10ml pack of CSB contains 5.73 grams of elemental calcium which is subsequently released over a 30-60-day interval. There is limited information on the mechanism of hypercalcemia secondary to CSB use, so further studies need to be implemented. Ultimately, it is crucial for physicians to have a high suspicion for CSB induced hypercalcemia post-arthroplasty as CSB use expands. Presentation: Saturday, June 17, 2023