Hypomagnesemia and its association with calcineurin inhibitor use in renal transplant recipients

Background Hypomagnesemia is a common electrolyte abnormality following kidney transplantation. Increased renal magnesium (Mg) waste has been linked to calcineurin inhibitors. We aimed to assess the prevalence and risk factors of hypomagnesemia and its association with calcineurin inhibitor use in renal transplant recipients. Patients and methods This is a cross-sectional study carried out on renal transplant recipients, who underwent living-related donor kidney transplantation. All participants underwent detailed history taking and complete physical examination. Serum Mg, trough level of cyclosporine or tacrolimus, fractional excretion of Mg (FEMg), and 24 h urinary Mg, Ca, Ph, Cl, and protein were measured. Results One hundred patients were screened and 80 patients, with a mean age of 39.65 ± 12.14 years, completed the study. Fifty (62.5%) patients were on tacrolimus, and 26 (32.5%) patients were on cyclosporine. Patients had a median serum Mg of 1.80 mg/dl. Hypomagnesemia (Mg<1.7) was present in 17 (21.3%) patients with a median FEMg of 3.08%. There was significant negative correlation between serum Mg level and trough level of tacrolimus and FEMg with a P value of 0.038 and 0.001, respectively. The results of multivariate analyses showed that tacrolimus trough level (P=0.010) and FEMg (P=0.025) were independently correlated with serum Mg. Hypomagnesemia was significantly higher in tacrolimus-treated patients (30%) compared with only 7.7% in cyclosporine-treated patients (P=0.027). Conclusions Hypomagnesemia is common in renal transplant recipients, especially with tacrolimus use mostly due to increased renal Mg wasting. Increased tacrolimus trough level and increased FEMg were predictors of hypomagnesemia.