An electrolyte abnormality may occur during apheresis therapy. Electrolyte abnormalities are among the major complications that can occur with plasma exchange (PEx) and double filtration plasmapheresis (DFPP). Electrolyte balance complications reported during apheresis include abnormalities involving calcium, sodium, acid–base balance, potassium, and phosphate levels. Complications with electrolyte balance have been reported in about 2 % of PEx and DFPP procedures, with a rate of about 0–3 % critical or fatal complications [1, 2]. The most common electrolyte abnormality occurring during apheresis is hypocalcemia; Shemin et al. reported a frequency of about 6–8 % [2]. Patients with electrolyte abnormalities, including hypocalcemia, are at risk for developing a life-threatening arrhythmia. Many of these electrolyte abnormalities can be prevented with electrocardiographic monitoring and other measures.