Incidence and Risk Factors of Hypokalemia in Patients With Multiple Myeloma Undergoing Autologous Peripheral Blood Stem Cell Collection

ABSTRACT Autologous peripheral blood stem cell (APBSC) collection is a standard procedure for patients with multiple myeloma (MM) undergoing hematopoietic stem cell transplantation. Hypokalemia is a frequently observed but underappreciated complication during apheresis, with limited evidence on its incidence and risk factors. To determine the incidence of hypokalemia following APBSC collection in MM patients and to identify independent risk factors. This retrospective cohort study consecutively enrolled 109 MM patients who underwent their first APBSC collection at Union Hospital, Fujian Medical University, between January 2018 and December 2022. All patients received prophylactic potassium supplementation during collection. Patients were stratified by serum potassium measured 2 h postprocedure: hypokalemia (< 3.5 mmol/L; n = 59) and normokalemia (3.5–5.0 mmol/L; n = 50). Variables with p < 0.10 in univariate analysis were entered into multivariable logistic regression with backward elimination. Post‐APBSC serum potassium was significantly lower than baseline (3.46 ± 0.43 vs. 3.85 ± 0.22 mmol/L; p < 0.001). Hypokalemia developed in 59 patients (54.1%): 48 mild (81.4%), nine moderate (15.3%), and two severe (3.4%). Three independent predictors were identified by multivariable analysis: higher body mass index (BMI) (OR 1.217; 95% CI 1.030–1.439; p = 0.021), higher hematocrit (OR 1.119; 95% CI 1.032–1.213; p = 0.006), and lower preprocedure serum potassium (OR 1.43 per 0.1 mmol/L decrease; 95% CI 1.15–1.78; p = 0.001). The model demonstrated adequate calibration (Hosmer–Lemeshow p = 0.635) and explained 24.6% of variance (Nagelkerke R 2 = 0.246). Hypokalemia affects over half of MM patients undergoing APBSC collection. Preprocedure risk factors (BMI, hematocrit, baseline potassium) may help identify high‐risk patients for whom intensified electrolyte monitoring and individualized supplementation strategies are warranted.