SUN-804 Risk Factors For Hypercalcemia In Patients With Rhabdomyolysis: A Retrospective Study

Abstract Disclosure: Y. Kim: None. E.Y. Lee: None. C. Liu: None. Introduction: Hypercalcemia (H-Ca) during the recovery phase of acute renal failure associated with rhabdomyolysis (rhabdo) is rare. Release of calcium (Ca) from deposits in injured tissues has been proposed as a mechanism. We aimed to evaluate risk factors for developing H-Ca in patients recovering from rhabdo, which may influence clinical management and outcomes. Methods: We retrospectively reviewed medical records of 58 patients (mean age 44.6 years; 69% male) admitted with rhabdo to an urban tertiary hospital between October 1, 2022, and October 23, 2024. Patients were divided into two groups based on the presence or absence of hypercalcemia. Comparisons were made using the t-test. We analyzed sociodemographic data (age, sex, and ethnicity), laboratory values (Na, K, CPK, Ca, Alb, P, Cr, PTH, CTX, P1NP, bone-specific alkaline phosphatase, and COVID status), EKG findings (presence of arrhythmia), length of hospital stay, and Charlson Comorbidity Index (CCI). Hypercalcemia was defined as corrected calcium >10.5 mg/dL or ionized calcium >1.34 mmol/L. Results: Of the 58 patients, 3 developed post-rhabdomyolysis hypercalcemia. These patients were older (mean age 56; p = 0.46), had longer hospital stays (mean 86 days; p = 0.213), and all underwent hemodialysis (p < 0.001) with a high-calcium dialysate (p = 0.19). They had significantly lower total calcium (mean 5.93 mg/dL; p = 0.033) and ionized calcium (mean 0.83 mmol/L; p = 0.004) during hospitalization. Their median sodium level was significantly lower (136.5 mmol/L; p < 0.001), and peak phosphorus was higher (mean 11.57 mg/dL; p = 0.04). Male sex (p < 0.001) and non-Hispanic ethnicity (p = 0.006) were significantly associated with the development of hypercalcemia. EKG findings, CCI, age, COVID status, CPK, K, Cr levels were not statistically significant. Due to limited data, PTH, CTX, P1NP, and bone-specific alkaline phosphatase were not assessed. Conclusion: H-Ca following rhabdo is rare. High phosphorus, low sodium, low total and ionized calcium, male sex, non-Hispanic ethnicity, and dialysis requirement were associated with its development. Patients receiving dialysis and calcium supplementation during rhabdo were more likely to develop hypercalcemia. Clinicians should be aware of these associations to avoid unnecessary calcium supplementation and better manage this potentially preventable complication. Presentation: Sunday, July 13, 2025