[Analysis of the efficacy and safety of bone disease treatment in patients with newly diagnosed multiple myeloma treated with denosumab or zoledronic acid].

Objective: This study investigated the efficacy and safety of denosumab (DENOS) versus zoledronic acid (ZOL) in the bone disease treatment of newly diagnosed multiple myeloma. Methods: The clinical data of 80 patients with myeloma bone disease (MBD) at the Fifth Medical Center of PLA General Hospital between March 1, 2021 and June 30, 2023 were retrospectively reviewed. Eighteen patients with severe renal impairment (SRI, endogenous creatinine clearance rate<30 ml/min) were treated with DENOS, and 62 non-SRI patients were divided into DENOS (30 patients) and ZOL group (32 patients) . Results: Hypocalcemia was observed in 26 (33%) patients, and 22 patients developed hypocalcemia during the first treatment course. The incidence of hypocalcemia in the non-SRI patients of DENOS group was higher than that in the ZOL group [20% (6/30) vs 13% (4/32), P=0.028]. The incidence of hypocalcemia in SRI was 89% (16/18). Multivariate logistic regression analysis revealed that endogenous creatinine clearance rate<30 ml/min was significantly associated with hypocalcemia after DENOS administration (P<0.001). After 1 month of antiresorptive (AR) drug application, the decrease in the serum ß-C-terminal cross-linked carboxy-telopeptide of collagen type I concentrations of SRI and non-SRI patients in the DENOS group were significantly higher than that in the ZOL group (68% vs 59% vs 27%, P<0.001). The increase in serum procollagen type Ⅰ N-terminal propeptide concentrations of patients with or without SRI in the DENOS group were significantly higher than that in the ZOL group (34% vs 20% vs 11%, P<0.05). The level of intact parathyroid hormone in each group increased after AR drug treatment. None of the patients developed osteonecrosis of the jaw and renal adverse events, and no statistically significant differences in the overall response rate, complete remission and stringent complete remission rates were found among the groups (P>0.05), and the median PFS and OS time were not reached (P>0.05) . Conclusions: In the treatment of MBD, DENOS minimizes nephrotoxicity and has strong AR effect. Hypocalcemia is a common adverse event but is usually mild or moderate and manageable.

External Validation and Update of the Risk Prediction Model for Denosumab-Induced Hypocalcemia Developed From a Hospital-Based Administrative Database.

PURPOSE: Denosumab is used to treat patients with bone metastasis from solid tumors, but sometimes causes severe hypocalcemia, so careful clinical management is important. This study aims to externally validate our previously developed risk prediction model for denosumab-induced hypocalcemia by using data from two facilities with different characteristics in Japan and to develop an updated model with improved performance and generalizability. METHODS: In the external validation, retrospective data of Kameda General Hospital (KGH) and Miyagi Cancer Center (MCC) between June 2013 and June 2022 were used and receiver operating characteristic (ROC)-AUC was mainly evaluated. A scoring-based updated model was developed using the same data set from a hospital-based administrative database as previously employed. Selection of variables related to prediction of hypocalcemia was based on the results of external validation. RESULTS: For the external validation, data from 235 KGH patients and 224 MCC patients were collected. ROC-AUC values in the original model were 0.879 and 0.774, respectively. The updated model consisting of clinical laboratory tests (calcium, albumin, and alkaline phosphatase) afforded similar ROC-AUC values in the two facilities (KGH, 0.837; MCC, 0.856). CONCLUSION: We developed an updated risk prediction model for denosumab-induced hypocalcemia with small interfacility differences. Our results indicate the importance of using data from plural facilities with different characteristics in the external validation of generalized prediction models and may be generally relevant to the clinical application of risk prediction models. Our findings are expected to contribute to improved management of bone metastasis treatment.

Increased risk of hypocalcemia with decreased kidney function in patients prescribed bisphosphonates based on real-world data from the MID-NET® in Japan: a new-user cohort study.

BACKGROUND: In the post-marketing stage, cases of hypocalcemia associated with bisphosphonate preparations (BPs) have been reported in patients with decreased kidney function, despite warning against use of BPs in such patients in the package insert (PI) of Japan. The purpose of this study was to investigate the safety of BPs in patients with decreased kidney function. METHODS: The cohort study was conducted in patients with osteoporosis and newly prescribed bisphosphonate utilizing real-world data from MID-NET® in Japan. The adjusted hazard ratios (aHRs) for hypocalcemia (a corrected serum Ca level < 8.00 mg/dL) relative to the normal group were calculated in each decreased kidney function group (mild, moderate or severe group). RESULTS: A total of 14,551 patients were included in the analysis, comprising 2,601 (17.88%) with normal (eGFR ≥ 90 mL/min/1.73m2), 7,613 (52.32%) with mild (60 ≤ eGFR < 90 mL/min/1.73m2), 3,919 (26.93%) with moderate (30 ≤ eGFR < 60 mL/min/1.73m2), and 418 (2.87%) with severe kidney function (eGFR < 30 mL/min/1.73m2). The aHRs (95% confidence interval) for hypocalcemia were 1.85 (0.75-4.57), 2.30 (0.86-6.21), and 22.74 (8.37-61.78) in the mild, moderate, and severe groups, respectively. The increased risk of hypocalcemia depending on kidney function was also observed even when calculating the aHR for each specific BP such as alendronate sodium hydrate, minodronic acid hydrate, and sodium risedronate hydrate. Furthermore, similar results were obtained in the sensitivity analysis by altering the outcome definition to a 20% or more reduction in corrected serum Ca level from the baseline, as well as when focusing on patients with more than one laboratory test result per 30 days during the follow-up period. CONCLUSIONS: These findings suggest that the risk of hypocalcemia during BP prescription is higher in patients with decreased kidney function, particularly those with severely decreased kidney function. The quantitative real-world evidence on the safety risk of BPs obtained in this study has led to the PI revision describing a relationship between hypocalcemia risk and decreased kidney function as a regulatory action in Japan and will contribute to promoting the proper use of BPs with appropriate risk management in clinical practice.

Recurrent severe hypocalcemia following chemotherapy regimen changes in advanced breast cancer: two case reports.

BACKGROUND: As an oncologic emergency related to abnormalities in calcium metabolism, hypercalcemia associated with paraneoplastic syndrome and bone metastases is well known. Meanwhile, the incidence of hypocalcemia is low, except in cases associated with bone-modifying agents used for bone metastases. Hypocalcemia induced by bone-modifying agents typically occurs early after the initial administration, and its incidence can be significantly reduced by preventive administration of calcium and vitamin D3 supplements. CASE REPORT: We report two cases of recurrent severe hypocalcemia occurring during chemotherapy for metastatic breast cancer with multiple bone metastases. Case 1: A 35-year-old Japanese woman developed metastases in the bone, liver, and ovaries during postoperative endocrine therapy for invasive lobular carcinoma of the breast. She underwent chemotherapy and treatment with denosumab. She experienced recurrent episodes of severe hypocalcemia subsequent to a change in the chemotherapy regimen. Case 2: A 65-year-old Japanese woman encountered multiple bone metastases after postoperative anti-human epidermal growth factor receptor 2 therapy and during endocrine therapy for invasive ductal carcinoma of the breast. She underwent anti-human epidermal growth factor receptor 2 therapy and treatment with denosumab. She experienced recurrent severe hypocalcemia subsequent to a change in the chemotherapy regimen to letrozole + lapatinib, trastuzumab emtansine, and lapatinib + capecitabine. CONCLUSIONS: We observed two cases of recurrent severe hypocalcemia in patients with advanced breast cancer and bone metastases after modifications to their therapy regimens. These cases differed from the typical hypocalcemia induced by bone-modifying agents. It is possible that antitumor drugs affect calcium and bone metabolism associated with bone metastases. While these cases are rare, it is crucial for oncologists to be aware of hypocalcemia not only at the initiation of bone-modifying agents but also throughout the entire antitumor therapy, as hypocalcemia can lead to fatal outcomes.

Denosumab-induced hypocalcemia in patients with solid tumors and renal dysfunction: a multicenter, retrospective, observational study.

BACKGROUND: Bone metastases are frequently observed in advanced cancer, and bone modifying agents are used to prevent or treat skeletal-related events. Zoledronic acid is contraindicated in patients with severe renal impairment (Ccr < 30 mL/min), but it is not completely known whether denosumab can be used in them. We aimed to determine the association between renal function and hypocalcemia development during denosumab treatment. METHODS: We included patients with solid cancer and bone metastases who started denosumab treatment between April 2017 and March 2019. They were classified into four groups based on creatinine clearance (Ccr; mL/min): normal (Ccr ≥ 80), mild (50 ≤ Ccr ˂80), moderate (30 ≤ Ccr ˂50), and severe (Ccr ˂30). Hypocalcemia was evaluated using the Common Terminology Criteria for Adverse Events (v5.0) based on the albumin-adjusted serum calcium levels; its incidence (stratified by renal function) and risk factors were investigated using a Chi-square test and logistic regression analysis. RESULTS: Of 524 patients (age: 69 ± 11 years; 303 men), 153 had a normal renal function and 222, 117, and 32 had mild, moderate, and severe renal dysfunction. The albumin-adjusted serum calcium level was higher than the measured (total) calcium level in most patients. The incidence of grade ≥ 1 hypocalcemia was 32.0% in the normal group and 37.4%, 29.9%, and 62.5% in the mild, moderate, and severe renal dysfunction groups, respectively. It was, therefore, higher in the severe renal dysfunction groups than in the normal group (P = 0.002). The incidence of grade ≥ 3 hypocalcemia did not differ significantly among the groups. Pre-treatment low serum calcium levels and severe renal dysfunction were risk factors for hypocalcemia. CONCLUSIONS: Evaluating denosumab-induced hypocalcemia required albumin adjustment, and its incidence was high among patients with severe renal dysfunction. Reduced serum calcium levels and severely impaired renal function were associated with an elevated hypocalcemia risk.

Acute hypernatremia and hypocalcemia after oral sodium phosphate administration to a dog.

A 15-year-old male neutered mixed breed dog weighing 28 kg presented to a referral center after developing severe tremors and altered mentation. There was hypocalcemia and hypernatremia after oral administration of sodium phosphate as a bowel cleansing agent in preparation for colonoscopy. The dog was treated intravenously with low sodium fluids and calcium gluconate. Neurologic status and electrolyte derangements normalized over the next 12 hours. Oral administration of sodium phosphate appeared to cause clinical electrolyte derangements in this dog.

Risk factors for taxane-induced peripheral neuropathy in patients with breast cancer.

PURPOSE: This study investigated the clinical risk factors for peripheral neuropathy induced by docetaxel and albumin-bound paclitaxel (AP) in patients with breast cancer. METHODS: This prospective observational study recruited 268 patients between March 2019 and December 2020. Patient information was obtained through the query system for laboratory test results, patient consultations, and scale evaluations. Neuropathic symptoms were followed up throughout and until 3 months after taxane chemotherapy. Univariate and multivariate analyses were used to find the risk factors for overall and moderate-severe taxane-induced peripheral neuropathy (TIPN). RESULTS: Cumulative dose (odds ratio [OR] = 3.533, 95% confidence interval [CI]: 1.797-6.944, p < 0.001), body mass index (BMI) (OR = 2.926, 95% CI: 1.621-5.281, p < 0.001), body surface area (BSA) (OR = 1.724, 95% CI: 1.011-2.941, p = 0.045), and hypocalcemia (OR = 4.899, 95% CI: 1.518-15.811, p = 0.008) all increased the risk of TIPN. Only cumulative dose (OR = 2.577, 95% CI: 1.161-5.719, p = 0.020) and BSA (OR = 2.040, 95% CI: 1.073-3.877, p = 0.030) were independent risk factors for moderate-severe TIPN. CONCLUSION: Cumulative dose, BMI, BSA, and hypocalcemia are all risk factors for overall TIPN, whereas cumulative dose and BSA are risk factors for moderate-severe TIPN. Patients with breast cancer who have high BMI, large BSA, hypocalcemia, and large cumulative dose may be at risk of TIPN, and intervention measures must be actively carried out for them.

Assessing the Role of Initial Serum Calcium Concentration in Patients with Ethylene Glycol Poisoning.

INTRODUCTION: Assays for ethylene glycol (EG) with a rapid turn-around time are not routinely available. Clinicians must rely on historical features and readily available clinical tests, combined with clinical acumen, to guide the initial management of suspected EG poisoning. Hypocalcemia has been suggested as a clue supporting the diagnosis of EG poisoning in patients presenting with an unexplained high anion gap metabolic acidosis (HAGMA). A previous small study challenged this assumption. METHODS: This was a retrospective case series of one state's poison control system of confirmed EG-poisoned patients between September 2017 and April 2021. The definition of EG poisoning was based on suspected EG ingestion and a serum EG concentration > 5 mg/dL. Patients who were suspected to have EG toxicity but did not have a confirmed EG concentration or the EG concentration was less than 5 mg/dL were excluded. Routine laboratory studies were recorded for all patients. Comparisons between serum calcium on presentation to presenting blood pH, bicarbonate, anion gap, and creatinine were assessed for correlation. RESULTS: There was no correlation between the presenting calcium and either pH or creatinine. There was a weak positive correlation between the initial serum calcium and anion gap, a weak negative correlation between the initial serum calcium and bicarbonate. CONCLUSION: On hospital presentation, hypocalcemia was not associated with EG poisoning, even in patients with a HAGMA. A normal serum calcium on presentation does not exclude the diagnosis of EG poisoning.

Treatment of osteoporosis with denosumab in patients with decreased kidney function.

INTRODUCTION: Little is known about treatment of osteoporosis with denosumab (Prolia®) in patients with decreased kidney function. The aim of this retrospective case report study was to investigate effects and side-effects of such treatment. METHODS: Since 2012, 75 patients with osteoporosis and decreased kidney function had been treated with denosumab (Prolia®) in the osteoporosis outpatient clinic of the department of endocrinology, Bispebjerg Hospital, University of Copenhagen, Denmark, and data were retrospectively collected from the patient records of these patients in 2021. RESULTS: At baseline, the mean estimated glomerular filtration rate (eGFR) was 34 mL/min (range 9-50) and the median age was 85 years (range 45-103). 95% of the patients had had low-energy fractures, and the bone mineral density T score of the hips was on average - 2.7. All, but one, patients had normal/high parathyroid hormone (PTH) levels. The mean duration of the treatment with denosumab at the follow-up was 5.3 years (range 1.5-10). There was an annual increase of 12% and of 7% in the T score of in the lumbar spine and hip, respectively, compared to the T-scores prior to the denosumab treatment. 20% had a new fracture during the follow-up. 21% had biochemical hypocalcemia following denosumab injection, 7% developed symptoms of hypocalcemia, whereas 4% needed to be hospitalized acutely. CONCLUSION: Treatment with denosumab of osteoporosis in patients with decreased kidney function (eGFR 9-50 mL/min), with normal/high PTH, seems in general to be well tolerated, with improvement of bone and decreased risk of new fractures.

The Tyr Phenomenon: A Hypocalcemic Response in High-Volume Treatment Responders to 177Lu-Prostate-Specific Membrane Antigen Therapy.

177Lu-prostate-specific membrane antigen (PSMA) is an effective treatment for metastatic castration-resistant prostate cancer. Rarer treatment-related adverse events have not yet been described. Methods: We present case reviews of 2 men with a marked hypocalcemic osteosclerotic response to 177Lu-PSMA-I&T therapy. A clinical dataset of 177Lu-PSMA-I&T therapy was evaluated to estimate the incidence and clinical association with hypocalcemia. Results: Forty-one of the 127 men (32%) had a serum calcium drop, and 6 (5%) developed clinical hypocalcemia during 177Lu-PSMA therapy. The baseline total tumor volume was significantly higher in those who developed hypocalcemia (median, 3,249 cm3 [interquartile range, 1,856-3,852] vs. 465 [interquartile range 135-1,172]; P = 0.002). The mean prostate-specific antigen response in those with hypocalcemia was 78% (SD, 24%). Conclusion: Hypocalcemia may occur in response to 177Lu-PSMA-I&T, particularly with both high-volume bone metastases and a significant prostate-specific antigen response, and may be severe, requiring corticosteroids. Further evaluation of 177Lu-PSMA-induced hypocalcemia is required to better understand mechanisms, optimal treatments, and repercussions from any subsequent osteosclerotic response.

Electrolytes Play a Role in Detecting Cisplatin-Induced Kidney Complications and May Even Prevent Them-Retrospective Analysis.

Background and Objective: Cisplatin is a chemotherapy drug used to treat several types of malignancies. It is a platinum-based compound that interferes with cell division and DNA replication. Cisplatin has been associated with renal damage. This study evaluates the early detection of nephrotoxicity through routine laboratory tests. Materials and Methods: This is a retrospective chart review based on the Saudi Ministry of National Guard Hospital (MNGHA). We evaluated deferential laboratory tests for cancer patients treated with cisplatin between April 2015 and July 2019. The evaluation included age, sex, WBC, platelets, electrolytes, co-morbidities and interaction with radiology. Results: The review qualified 254 patients for evaluation. Around 29 patients (11.5%) had developed kidney function abnormality. These patients presented with abnormally low magnesium 9 (31%), potassium 6 (20.7%), sodium 19 (65.5%) and calcium 20 (69%). Interestingly, the whole sample size had abnormal electrolytes presenting magnesium 78 (30.8%), potassium 30 (11.9%), sodium 147 (58.1%) and calcium 106 (41.9%). Some pathological features were detected, such as hypomagnesemia, hypocalcemia and hypokalemia. In addition, infections that needed antibiotics were dominant in patients treated with cisplatin alone, representing 50% of this group. Conclusions: We report that an average of 15% of patients with electrolyte abnormalities develop renal toxicity and reduced function. Moreover, electrolytes may serve as an early indicator for renal damage as part of chemotherapy complication. This indication represents 15% of renal toxicity cases. Changes in electrolyte levels have been reported with cisplatin. Specifically, it has been linked to hypomagnesemia, hypocalcemia and hypokalemia. This study will help reduce the risk of dialysis or the need for kidney transplant. It is also important to manage any underlying conditions and control patients' intake of electrolytes.

Hypocalcemia During Lenvatinib Treatment for Advanced Thyroid Cancer: Clinical Features and Management in a Real-Life Setting.

Background: Several toxicities are recorded during treatment of advanced thyroid cancer (TC) with antiangiogenic drugs, including lenvatinib (LEN). Hypocalcemia was reported in registration studies, but little data are available from real-life cohorts. The aim of our study was to describe the incidence, characteristics, and the management of hypocalcemia in patients on LEN treatment. Methods: This is a retrospective cohort study of consecutive patients with advanced TC, treated with LEN for at least six months at a single tertiary center in Italy. Phosphocalcic metabolism was evaluated during treatment. Results: We included 25 patients treated for a mean of 29 ± 19 months (range 6-68 months). Hypocalcemia occurred in 6 of the 25 patients (24% [95% confidence interval 9.36-45.13%]), being of grade ≥3 in 2 of the 25 patients (8%), and recurrent in 4 of 6 patients (67%). The median time to hypocalcemia onset was 3 months (range 0.5-13 months) from starting LEN. No differences were found between patients who developed or not hypocalcemia regarding either starting/mean dose of LEN or clinicopathological characteristics. During the hypocalcemic crisis, the 2 patients with grade ≥3 hypocalcemia had low magnesium and low or inappropriately normal parathormone (PTH) levels, while 2 of 3 patients with grade 2 hypocalcemia had a secondary hyperparathyroidism. Hypocalcemia was managed with calcium oral supplementation in most cases, although up to 10% of patients required intravenous calcium treatment and transient LEN withdrawal. Conclusions: In this relatively small cohort, we observed an incidence of hypocalcemia of 24%, which is higher than that reported in the registration trial (6.9%). Both PTH-dependent and PTH-independent mechanisms explained hypocalcemia in the present cohort. Monitoring of serum calcium levels is strongly advised during the first year of LEN treatment, as hypocalcemia may be severe. More research is needed to confirm our findings and inform possible risk factors for hypocalcemia in advanced TC patients treated with LEN.

Development of Risk Prediction Model for Grade 2 or Higher Hypocalcemia in Patients With Bone Metastasis Treated With Denosumab Plus Cholecalciferol (Vitamin D3 )/Calcium Supplement.

Denosumab-induced hypocalcemia is sometimes severe, and although a natural vitamin D/calcium combination is used to prevent hypocalcemia, some patients rapidly develop severe hypocalcemia even under supplementation. It is clinically important to predict this risk. This study aimed to develop a risk prediction model for grade ≥2 hypocalcemia within 28 days after the first denosumab dose under natural vitamin D/calcium supplementation. Using a large database containing multicenter practice data, 2399 patients with bone metastasis who were treated with denosumab between June 2013 and May 2020 were retrospectively analyzed. Background factors in patients who developed grade ≥2 hypocalcemia within 28 days after the first denosumab dose and those who did not were compared by univariate analysis. Multivariate analysis was conducted to develop a risk prediction model. The model was evaluated for discriminant performance (receiver operating characteristic-area under the curve, sensitivity, specificity) and predictive performance (calibration slope). A total of 124 patients in the hypocalcemia group and 1191 patients in the nonhypocalcemia group were extracted. A risk prediction model consisting of sex, calcium, albumin, alkaline phosphatase, osteoporosis, breast cancer, gastric cancer, proton pump inhibitor combination, and pretreatment with zoledronic acid was developed. The receiver operating characteristic-area under the curve was 0.87. Sensitivity and specificity were 83% and 81%, respectively, and the calibration slope indicated acceptable agreement between observed and predicted risk. This model appears to be useful to predict the risk of denosumab-induced hypocalcemia and thus should be helpful for risk management of denosumab treatment in patients with bone metastases.

Safety and efficacy of bone-modifying agents among multiple myeloma patients: A retrospective cohort study.

OBJECTIVE: To determine the incidence of skeletal-related events among multiple myeloma patients who received chemotherapy without a bone-modifying agent (zoledronic acid and denosumab) versus those who received chemotherapy with a bone-modifying agent. The secondary objective was to determine the incidence of skeletal-related events in patients without any prior history of skeletal-related events and who were treated with zoledronic acid every four weeks versus those who received zoledronic acid at an extended interval of every twelve weeks. Additional secondary objectives included the incidence of nephrotoxicity, hypocalcemia and osteonecrosis of the jaw in all patients. METHODS: This institutional review board-approved, retrospective cohort study included patients 18 to 89 years old with a diagnosis of multiple myeloma, who were being treated with chemotherapy between July 1, 2016 and October 31, 2019. Safety and efficacy were assessed through analysis of pertinent data collected: patient demographics, baseline skeletal-related events, development of new skeletal-related events, number and type of bone-modifying agent doses administered, and drug-related toxicities such as nephrotoxicity, hypocalcemia, and osteonecrosis of the jaw. RESULTS: A total of 73 patients were included. New skeletal-related events occurred in 12 patients (27%) in the chemotherapy without a bone-modifying agent group and in 5 patients (17%) in the chemotherapy with a bone-modifying agent group (OR = 0.56, 95% CI [0.172-1.8]; P = 0.32). The incidence of skeletal-related events was similar among patients receiving zoledronic acid every four weeks versus every twelve weeks in patients without a prior skeletal-related event (N = 0 vs. N = 2 respectively; P = 0.47). There were no statistically significant differences observed in each of the three secondary safety endpoints: incidence of hypocalcemia, nephrotoxicity and osteonecrosis of the jaw. CONCLUSION: Multiple myeloma patients receiving chemotherapy without a bone-modifying agent had higher rates of skeletal-related events compared to those being treated with chemotherapy and a bonemodifying agent. Our results highlight the benefit of utilizing bonemodifying agents for the prevention of skeletal-related events in all multiple myeloma patients being treated with chemotherapy.

Life-threatening sustained hypocalcemia following Denosumab use in metastatic prostate cancer.

INTRODUCTION: Prostate cancer is the second most frequently diagnosed cancer among men worldwide in 2020. Skeletal-related events (SRE) like pathologic fracture or spinal cord compression are commonly seen in metastatic prostate cancer. Denosumab, a monoclonal antibody, acts by inhibiting osteoclast-mediated bone resorption in bone metastasis from solid tumors and reduces bone turnover and destruction. However, there is an increased risk of life-threatening denosumab-induced hypocalcemia with an incidence of 0.1 to 12.8%. CASE REPORT: Our patient is a 69-year-old man with widespread skeletal metastatic disease from primary prostate cancer who presented to the hospital complaining of generalized fatigue and joint pain. Due to severe debilitating low back pain secondary to osteochondral lesions, the patient was started on Denosumab 120 mg. On presentation, serum calcium was found to be severely low at 5.9 mg/dl (serum calcium level prior to Denosumab was 9.1 mg/dl). MANAGEMENT AND OUTCOME: Denosumab was discontinued immediately, and the patient was started on IV calcium gluconate. Repeat serum calcium level continued to be low at 6.7 likely due to the long elimination half-life of Denosumab (25-30 days). He was transferred to a long-term acute care facility for long-term IV calcium replacement, where he succumbed to illness six weeks later. DISCUSSION: Denosumab, an anti-resorptive treatment for skeletal metastasis from solid tumors, is shown to cause severe life-threatening hypocalcemia. The maximum serum drug level of Denosumab reaches 7-21 days after administration. Sustained hypocalcemia is rare and life-threatening. Clinicians should use this medication with caution due to its unpredictable side effect profile.

Denosumab-induced hypocalcemia in a patient with hyperthyroidism: a case report.

Denosumab is a humanized monoclonal antibody targeting the receptor activator of nuclear factor kappa-B ligand (RANKL). Denosumab is an effective treatment for osteoporosis but can cause hypocalcemia. We present a case of denosumab-induced hypocalcemia in a patient with hyperthyroidism with a high bone turnover state. A 48-year-old postmenopausal woman was diagnosed with hyperthyroidism and osteoporosis and received antithyroid drugs (propylthiouracil 200 mg/day) and denosumab. After 2 months of taking medication, the patient complained of numbness and tingling in the hands and feet and was diagnosed with hypocalcemia (calcium, 5.8 mg/dL; ionized calcium, 0.83 mmol/L). Alfacalcidol (0.5 µg/day) and calcium carbonate (3000 mg/day) were prescribed. Subsequently, the patient's symptoms improved, and her serum calcium level normalized. The risk of denosumab-induced hypocalcemia may be increased in patients with diseases related to high bone turnover, such as hyperthyroidism; therefore, caution is needed.