In this study, we investigated the effectiveness of regional citrate anticoagulation continuous renal replacement therapy (RCA-CRRT) in reducing blood calcium levels in three patients with hypercalcemia crisis caused by different etiologies. The sodium citrate chelation of calcium ions was utilized as an anticoagulant for treating severely affected patients. By adjusting the citrate anticoagulant dose and monitoring treatment indicators, RCA-CRRT parameters were actively modified to alleviate the hypercalcemia crisis and provide time for surgery or specialized treatment. Two patients experienced rapid and effective reductions in blood calcium levels, allowing for further treatment, while the third patient exhibited a repeated increase in blood calcium, which eventually decreased after parathyroid adenoma resection, leading to clinical discharge. Our findings suggest that RCA-CRRT can help alleviate hypercalcemia crisis, stabilize the patient's internal environment, and provide valuable time for clinical treatment in cases of various medical conditions causing abnormal blood calcium elevations.