A case of acute-onset hypermagnesemia with paralytic ileus

Abstract

A 77-year-old woman was admitted to the ICU following unexplained shock. She was primarily admitted to our hospital for postoperative rehabilitation. She had developed paralytic ileus after the operation and received magnesium oxide (990 mg/day) approximately 25 days before the ICU admission. The electrocardiography on admission revealed bradycardia with atrioventricular and sinoatrial block. Simultaneously, the results of her blood gas analysis showed that her serum ionic magnesium (iMg²⁺) concentration level was high, up to 2.34 mmol/L, which is equal to a total serum magnesium (Mg) concentration level of 11.9 mg/dL. Since we assumed that hypermagnesemia was the primary cause of the shock, continuous hemodiafiltration to decrease the serum Mg concentration level was performed. With a decrease in serum Mg concentration level, the heart rate returned to normal sinus rhythm, and she recovered from the shock. She was discharged from the ICU on the 12th day. Retrospective data showed that serum Mg concentration level elevated rapidly the day before admission to the ICU. As we have known previously, most cases of hypermagnesemia in the elderly patients are iatrogenically induced by Mg products, as evidenced by patients’ renal dysfunction. In such cases, dysfunction of Mg excretion results in a gradual elevation of serum Mg levels. However, as in this case, acute elevation of serum Mg levels is accompanied with paralytic ileus because intestinal Mg absorption is promoted; i.e., bowel obstruction becomes a cause of acute hypermagnesemia even if there is no preexisting renal dysfunction.