The 2023 Endocrine Society clinical practice guidelines on the treatment of hypercalcemia in malignancy (HCM) define severe HCM as serum calcium (SCa) >14 mg/dL (3.5 mmol/L). For these patients, it is suggested using a combination of calcitonin and an intravenous (IV) bisphosphonate or denosumab as initial treatment, rather than using an IV bisphosphonate or denosumab alone. This recommendation is based on a retrospective study involving 140 patients treated with a bisphosphonate and/or calcitonin for moderate to severe HCM (see Table 1; corrected SCa >13 mg/dL or ionized calcium >1.5 mmol/L). Additionally, the guidelines provide an alternative definition of hypercalcemia severity from the National Cancer Institute's Common Terminology Criteria for Adverse Events. [1]
Denosumab is highlighted as a key option for antiresorptive therapy in cancer-related hypercalcemia, particularly for patients with bisphosphonate-refractory disease. Denosumab is a fully human monoclonal antibody that targets RANKL, thereby preventing its interaction with the RANK receptor on osteoclast precursors and mature osteoclasts. This mechanism directly suppresses osteoclast formation, function, and survival, leading to reduced bone resorption and subsequent lowering of serum calcium levels. Clinically, denosumab is positioned as a second-line option after IV bisphosphonates for hypercalcemia of malignancy, administered as 120 mg subcutaneously every 4 weeks, with additional doses on days 8 and 15 during the first month. Comparative data cited in the review demonstrate that denosumab is more effective than zoledronic acid in preventing malignant hypercalcemia in patients with metastatic bone disease, delaying the first hypercalcemic episode (hazard ratio ~0.63) and reducing recurrent hypercalcemia risk by approximately 52%. Fewer patients receiving denosumab developed hypercalcemia compared with those treated with zoledronic acid (31% vs 40%). A major advantage of denosumab emphasized in the article is its safety profile in renal impairment. Unlike bisphosphonates, denosumab is not renally excreted and does not require dose adjustment or avoidance in patients with reduced glomerular filtration rate, making it particularly valuable in oncology patients with chronic kidney disease. However, the review underscores the increased risk of hypocalcemia, especially in patients with renal failure, necessitating close monitoring of serum calcium levels. Other notable adverse effects include osteonecrosis of the jaw and the potential for a “rebound phenomenon” upon discontinuation, characterized by increased bone turnover markers, loss of bone mineral density, and recurrent hypercalcemia; transition to a bisphosphonate after stopping denosumab is suggested to mitigate this risk. [2]
Additional review articles highlight that denosumab is not cleared by the kidney and has no renal toxicity, making it useful in patients with impaired renal function who cannot take bisphosphonates. It was also mentioned that because intravenous (IV) bisphosphonates may worsen renal insufficiency, their use is not recommended in patients with severe volume depletion or a CrCl<35 mL/min. Pharmacokinetic analyses have found no statistically significant association between GFR and systemic exposure to denosumab as measured by AUC0–113 days or Cmax across renal function groups. Pharmacodynamically, denosumab led to a rapid and sustained suppression of serum C-telopeptide (sCTX1) levels, with median reductions of 65–85% maintained throughout the study period. Higher baseline sCTX1 values were observed in subjects with kidney failure, as expected, but relative reductions were comparable across groups. Hypocalcemia was the most clinically notable adverse event, manifesting in 15% of the cohort, with two subjects, both with severe chronic kidney disease (CKD) and without adequate calcium/vitamin D supplementation, experiencing serious events requiring IV calcium infusion. Importantly, none of the patients who received appropriate supplementation developed clinically significant hypocalcemia. These findings suggest that renal impairment does not necessitate denosumab dose adjustment but highlight the critical need for calcium and vitamin D supplementation, particularly in those with advanced kidney disease. [3]
A 2022 review addressed the management of severe cancer-associated hypercalcemia, defined by corrected calcium levels >13 mg/dL, rapid rises in calcium, or neurologic symptoms. The authors emphasized aggressive intravenous isotonic saline hydration as initial therapy to correct volume depletion and promote calciuresis, followed by antiresorptive therapy as the cornerstone of treatment. Intravenous zoledronic acid was identified as the preferred agent, normalizing calcium levels in most patients within 48-72 hours, while calcitonin was recommended as a short-term adjunct for rapid but transient calcium reduction. Denosumab was supported as an effective alternative in patients with renal impairment or bisphosphonate-refractory disease, with glucocorticoids and dialysis reserved for select etiologies or life-threatening cases. The authors concluded that prompt hydration, early antiresorptive therapy, and treatment of the underlying malignancy are essential for sustained control of severe hypercalcemia. [4]
A 2018 meta-analysis of six observational studies examined the incidence of hypocalcemia and changes in bone mineral density (BMD) following denosumab treatment in end-stage renal disease (ESRD) patients undergoing dialysis. The analysis pooled data from 84 patients to evaluate denosumab's effects on serum calcium from baseline to post-treatment. The estimated incidence of hypocalcemia during denosumab therapy was 42% (95% confidence interval [CI] 29 to 55%). Hypocalcemia typically developed 7 to 20 days after the initial dose, with nadir calcium levels observed within 2 weeks to 2 months. The results suggest that while denosumab improves skeletal health, its use in this population requires careful calcium and vitamin D supplementation, alongside vigilant monitoring to mitigate hypocalcemia risks. Notably, this meta-analysis did not examine the rate of calcium level decline irrespective of hypocalcemia. [5]
A recent 2026 systematic review focused on the rarer manifestation of post-discontinuation hypercalcemia. The authors identified three prior studies, encompassing four postmenopausal women aged 64-86 years, and added one institutional case. All patients had received denosumab 60 mg every 6 months for 3-10 years, had severe osteoporosis, and had no prior bisphosphonate exposure. Hypercalcemia developed 3-11 months after the last denosumab dose, with corrected calcium levels ranging from 11.3 to 13.0 mg/dL. Cases were mild to moderate and asymptomatic, with markedly elevated bone turnover markers and low or suppressed parathyroid hormone levels, supporting rebound osteoclast activation as the likely mechanism. Two patients developed multiple vertebral fractures after discontinuation. Treatment involved restarting antiresorptive therapy, either with bisphosphonates or denosumab. Overall, hypercalcemia after denosumab withdrawal in osteoporosis appears rare and usually mild, but it may represent another clinical expression of the same rebound phenomenon that causes rapid bone loss and vertebral fractures. The review emphasizes that denosumab should not be stopped without planned sequential antiresorptive therapy and close monitoring for both skeletal complications and calcium abnormalities. [6]