Severe Hypophosphatemia Following Denosumab Administration in a Hemodialysis Patient with Progressive Prostate Cancer

In a 68-year-old man on maintenance hemodialysis (HD), severe anemia was detected. Bone marrow biopsy was performed for investigation of pancytopenia and pathological examination revealed adenocarcinoma of the prostate. Prostate specific antigen (PSA) was 574 ng/mL. After androgen deprivation therapy was initiated, PSA decreased to 13.7 ng/mL. But subsequent elevation of PSA and pain due to bone metastases were recognized. Denosumab (120 mg) was administered. Although improvement of bone pain was observed, severe hypocalcemia occurred. Severe hypophosphatemia was subsequently detected. When we use denosumab in dialysis patients with advanced cancer, we should be careful of hypophosphatemia.