Long-Term Efficacy of Etelcalcetide in a Patient on Hemodialysis with Refractory Secondary Hyperparathyroidism: A 15-Month Follow-Up Case Report

Introduction: While calcimimetics underpin modern SHPT management, first-generation agents are constrained by gastrointestinal intolerance and erratic calcium homeostasis. Etelcalcetide, an intravenously administered peptide calcimimetic, holds promise for overcoming these limitations. We detail the first documented 15-month etelcalcetide regimen in refractory SHPT, establishing critical benchmarks for therapeutic optimization. Case Description: A 46-year-old female with end-stage renal disease secondary to IgA vasculitis nephritis underwent thrice-weekly hemodialysis for 36 months. Persistent SHPT (baseline iPTH 200–500 pg/mL) proved resistant to sequential therapies: paricalcitol (5 μg biweekly, halted for hypercalcemia and hyperphosphatemia) and cinacalcet (25–50 mg daily, discontinued for severe dyspepsia). Pre-intervention evaluation (January 2024) demonstrated profound hyperparathyroidism (iPTH 994.7 pg/mL) despite normocalcemia (2.43 mmol/L), normophosphatemia (1.73 mmol/L), and stable alkaline phosphatase (98 U/L), with ultrasonographic confirmation of a hyperplastic right superior parathyroid gland (12 × 10 mm). Initiation of etelcalcetide (5 mg post-dialysis, thrice weekly) elicited rapid biochemical response: iPTH decreased by 62% within 4 weeks, accompanied by transient asymptomatic hypocalcemia (nadir 1.86 mmol/L) managed via oral calcium titration. Sustained treatment achieved durable iPTH control (150–300 pg/mL) across 15 months with no adverse drug reactions. Discussion: This case demonstrates the sustained efficacy and safety of etelcalcetide in refractory SHPT, with its intravenous administration circumventing limitations of conventional therapies. Dynamic monitoring of calcium and iPTH is crucial for maintaining therapeutic stability.Changes in serum levels of parathyroid hormone (PTH), calcium (Ca), and phosphorus (P)