Abstract: FR-PO1278
A Case of Calcitriol-Mediated Hypercalcemia in a Patient with Testicular Germ-Cell Tumor
Session Information
- Onconephrology: Diagnostic Dilemmas, Therapy-Related Toxicities, and Clinical Cases
October 23, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Onconephrology
- 1600 Onconephrology
Authors
- Onuchic, Fernando, Yale New Haven Health, New Haven, Connecticut, United States
- Moss, Emily, Yale New Haven Health, New Haven, Connecticut, United States
- Mella Soares Pessoa, Beatriz, UConn Health, Farmington, Connecticut, United States
- Joseph, Teresa, Yale New Haven Health, New Haven, Connecticut, United States
Introduction
We present a case of a young and otherwise healthy man who developed hypercalcemia of malignancy secondary to elevated calcitriol levels in the setting of metastatic testicular germ cell tumor.
Case Description
The patient is a 37-year-old Caucasian male with past medical history of exogenous anabolic steroid use who presented to the hospital for a 2-week history of neck mass, fevers, unintended weight loss and night sweats. Initial laboratory studies were remarkable for acute kidney injury, with creatinine of 2.8 mg/dL (presumed normal at baseline) and moderate hypercalcemia with total calcium of 13.9 mg/dL (with normal albumin levels). Additional workup revealed a normal phosphate level (3 mg/dL), an elevated alkaline phosphatase level (168 U/L), a suppressed parathyroid hormone (PTH) level (<6 pg/mL), a normal 25-hydroxy vitamin D level (35 ng/mL), a normal PTH-related protein level (1.8 pmol/L), and a high calcitriol level (128 pg/mL). Computed tomography of the abdomen showed extensive lymphadenopathy and bilateral mild hydronephrosis.
Patient was started on intravenous crystalloids and underwent bilateral percutaneous nephrostomy tube placement with improvement in calcium levels and renal function, with total calcium of 9.3 mg/dL and creatinine of 1.4 mg/dL at time of discharge. Cervical lymph node biopsy was positive for a germ cell tumor. Scrotal ultrasound showed thickening in the right epididymal tail, suggestive of a burnt-out primary site.
Discussion
Hypercalcemia of malignancy (HCM) is a common oncologic emergency, occurring in 20-30% of cancer patients. Increased production of calcitriol through 1-alpha-hydroxylation of 25-hydroxy vitamin D in macrophages is the least common of the 3 major HCM mechanisms, accounting for <1% of HCM patients and occurring mostly in hematologic malignancies such as lymphomas. Although much rarer, cases have been identified in solid tumors, such as germ cell tumors, breast cancers, ovarian cancers, sarcomas and even squamous cell carcinomas. Treatment usually involves supportive therapy with aggressive intravenous hydration and glucocorticoids to inhibit 1-alpha-hydroxylase. Bisphosphonates can be used, although their efficacy may be limited in cases of calcitriol-mediated HCM. This case highlights the importance of considering calcitriol overproduction as a differential for HCM, even in solid tumor cases.