Severe Hypocalcemia and Dramatic Increase in Parathyroid Hormone after Denosumab in a Dialysis Patient: A Case Report and Review of the Literature

Reducing the risk of denosumab-induced hypocalcemia in patients with advanced chronic kidney disease: a quality improvement initiative

Denosumab can improve bone health in advanced kidney disease (CKD) but is associated with hypocalcemia. We created a clinical care pathway focused on the safe provision of denosumab in advanced CKD that reduced the risk of hypocalcemia by 37% at our hospital. Similar pathways could be adopted and tested in other centers.

PURPOSE

There is an increased risk of hypocalcemia with denosumab in advanced chronic kidney disease (CKD). We aimed to reduce the proportion of patients with advanced CKD who experienced denosumab-induced hypocalcemia at our center.

METHODS

We conducted a quality improvement (QI) project of patients with CKD stage 3b or less (i.e., estimated glomerular filtration rate <45 mL/min/1.73m2 including dialysis) who were part of the Osteoporosis and Bone Disease Program at St. Joseph's Health Care London (Canada) between December 2020 and January 2023. Our intervention was a clinical care pathway which optimized CKD mineral and bone disorder (CKD-MBD) and 25-hydroxyvitamin levels; provided calcium and vitamin D prophylaxis; promoted multidisciplinary communication between bone and kidney specialists; and carefully monitored calcium post-denosumab injection. Our primary outcome measure was the proportion of patients with hypocalcemia (defined by albumin-corrected serum calcium <1.9mmol/L) at 60 days. Process measures included the appropriate provision of calcium and vitamin D prophylaxis. Balance measures included the development of hypercalcemia and hyperphosphatemia following prophylaxis. We used plan-do-see-act cycles to study four tests of change and presented results using descriptive statistics and run charts.

RESULTS

There were 6 patients with advanced CKD treated with denosumab prior to the implementation of our care pathway (March 2015-October 2020; 83% receiving dialysis). At the time of their denosumab injection, 83% were using 500-1000 mg of calcium, and 83% used 1000-2000 IU of vitamin D3. Fifty percent developed denosumab-induced hypocalcemia. Following the implementation of our care pathway, 15 patients (40% receiving dialysis) were treated with denosumab. Ninety-three percent received calcium at a daily dose of 350 to 2250 mg and 87% received 1000-2000 IU of vitamin D3. Thirteen percent developed denosumab-induced hypocalcemia. There was no hypercalcemia or hyperphosphatemia.

CONCLUSIONS

A clinical care pathway focused on the safe provision of denosumab in advanced CKD reduced the risk of hypocalcemia in patients treated in our hospital. Similar pathways could be adopted and tested in other centers.

Prediction Model of Postoperative Severe Hypocalcemia in Patients with Secondary Hyperparathyroidism Based on Logistic Regression and XGBoost Algorithm

Objective

A predictive model was established based on logistic regression and XGBoost algorithm to investigate the factors related to postoperative hypocalcemia in patients with secondary hyperparathyroidism (SHPT).

Methods

A total of 60 SHPT patients who underwent parathyroidectomy (PTX) in our hospital were retrospectively enrolled. All patients were randomly divided into a training set (n = 42) and a test set (n = 18). The clinical data of the patients were analyzed, including gender, age, dialysis time, body mass, and several preoperative biochemical indicators. The multivariate logistic regression and XGBoost algorithm models were used to analyze the independent risk factors for severe postoperative hypocalcemia (SH). The forecasting efficiency of the two prediction models is analyzed.

Results

Multivariate logistic regression analysis showed that body mass (OR = 1.203, P = 0.032), age (OR = 1.214, P = 0.035), preoperative PTH (OR = 1.026, P = 0.043), preoperative Ca (OR = 1.062, P = 0.025), and preoperative ALP (OR = 1.031, P = 0.027) were positively correlated with postoperative SH. The top three important features of XGBoost algorithm prediction model were preoperative Ca, preoperative PTH, and preoperative ALP. The area under the curve of the logistic regression and XGBoost algorithm model in the test set was 0.734 (95% CI: 0.595~0.872) and 0.827 (95% CI: 0.722~0.932), respectively.

Conclusion

The predictive models based on the logistic regression and XGBoost algorithm model can predict the occurrence of postoperative SH.

Osteoporosis in Patients with Chronic Kidney Diseases: A Systemic Review

Chronic kidney disease (CKD) is associated with the development of mineral bone disorder (MBD), osteoporosis, and fragility fractures. Among CKD patients, adynamic bone disease or low bone turnover is the most common type of renal osteodystrophy. The consequences of CKD-MBD include increased fracture risk, greater morbidity, and mortality. Thus, the goal is to prevent the occurrences of fractures by means of alleviating CKD-induced MBD and treating subsequent osteoporosis. Changes in mineral and humoral metabolism as well as bone structure develop early in the course of CKD. CKD-MBD includes abnormalities of calcium, phosphorus, PTH, and/or vitamin D; abnormalities in bone turnover, mineralization, volume, linear growth, or strength; and/or vascular or other soft tissue calcification. In patients with CKD-MBD, using either DXA or FRAX to screen fracture risk should be considered. Biomarkers such as bALP and iPTH may assist to assess bone turnover. Before initiating an antiresorptive or anabolic agent to treat osteoporosis in CKD patients, lifestyle modifications, such as exercise, calcium, and vitamin D supplementation, smoking cessation, and avoidance of excessive alcohol intake are important. Managing hyperphosphatemia and SHPT are also crucial. Understanding the complex pathogenesis of CKD-MBD is crucial in improving one’s short- and long-term outcomes. Treatment strategies for CKD-associated osteoporosis should be patient-centered to determine the type of renal osteodystrophy. This review focuses on the mechanism, evaluation and management of patients with CKD-MBD. However, further studies are needed to explore more details regarding the underlying pathophysiology and to assess the safety and efficacy of agents for treating CKD-MBD.

Denosumab-Induced Hypocalcemia after Billroth II Gastric Bypass Surgery

Hypocalcemia is a known risk following bariatric surgery and can contribute to the development of osteoporosis. Osteoporosis is commonly treated with denosumab, though denosumab can exacerbate underlying abnormalities in calcium homeostasis. We present the case of a 59-year-old female with severe hypocalcemia who had been treated with denosumab for osteoporosis three months before and had Billroth II gastric bypass surgery 15 years before, for bariatric purposes. Intravenous calcium supplementation was used to correct the initial electrolyte abnormality, and the patient was able to maintain appropriate calcium levels on high doses of oral calcium before discharge. Denosumab-induced hypocalcemia has been previously reported in patients with predisposing conditions including chronic kidney disease, primary sclerosing cholangitis, Crohn's disease, and a history of sleeve gastrectomy for marginal gastric ulcers. A few cases of hypocalcemia have been reported in patients with a history of bariatric surgery secondary to vitamin D deficiency, but this report is unique in demonstrating denosumab-induced hypocalcemia after bariatric surgery with normal vitamin D levels, suggesting a primary malabsorption of calcium. The risk of severe hypocalcemia should be considered before initiating denosumab to treat osteoporosis in patients with a history of bariatric surgery. If denosumab is initiated, serum calcium levels should be closely monitored, and patients should be educated about the importance of adherence to calcium supplementation.

Contrasting PTH Response of Denosumab Use in Dialysis Patients: A Report of 2 Cases

A common complication of end-stage renal disease (ESRD) is mineral and bone disorder. Yet, many anti-osteoporotic drugs are contraindicated in ESRD patients. Denosumab, a monoclonal antibody, does not require renal dose adjustment. However, its use is uncertain due to a lack of safety and efficacy of data in this population. Two hemodialysis patient cases of contrasting responses in parathyroid hormone (PTH) after denosumab administration were observed. Patient 1, a 62-years-old male received denosumab 60 mg at Day 0. His calcium decreased from 8.8 mg/dL to 6.8 mg/dL on Day 30. The PTH level increased from 265 pg/mL to 372 pg/mL after 30 days. Calcium and PTH levels approached normal range after increasing doses of vitamin D/calcium supplements, and calcitriol. Patient 2, a 72-years-old male on hemodialysis also received denosumab 60 mg on Day 0. His baseline calcium and PTH were 9.2 mg/dL and 420 pg/mL, respectively. On Day 30, his calcium level decreased (6.8 mg/dL) but, PTH level drastically increased (>5000 pg/mL). Denosumab commonly causes hypocalcemia and hyperparathyroidism since it inhibits osteoclast activation, reduces calcium release from bone and increases PTH levels as a compensatory mechanism. With a wait-and-watch approach, Patient 2’s levels approached the normal range (calcium 9.6 mg/dL and PTH 274 pg/mL at Day 90).