SCREENING FOR HYPOMAGNESEMIA IN CYCLOSPORINE OR FK 506 TREATED RENAL TRANSPLANT RECEIPIENTS.

Abstract

584 Therapy with cyclosporine (CSA) or FK 506 increases the urinary losses of magnesium (Mg) in renal transplant recipients. Hypomagnesemia (hypoMg) has been reported to be associated with hypertension, glucose intolerance, abnormal lipid metabolism and cardiovascular complications. Mg level is often not measured as part of the routine screening blood tests. We have evaluated different variables and the correlation between these variables to detect hypoMg in stable renal transplant recipients. We also evaluated effect of Mg repletion on the variables in hypoMg patients. Of 194 transplant recipients with a s.creatinine <3.0 on either FK 506 or CSA therapy, 14 (7.1%) were found to be hypoMg as defined by s.Mg level <1.6 or ionized Mg <0.90. 14 control patients were also evaluated for different variables of Mg measurement i.e. s.Mg, ion Mg, RBC Mg, Urine Mg (u.Mg) and fractional excretion of Mg (FEr Mg). All 28 patients had s.Mg in range of 1.3 to 2.2 mg/dl (mean 1.71±0.043) s.Mg correlated well with ion Mg (mean 0.97±0.02; R=0.67). Poor correlation was seen between s.Mg and RBC Mg, Urine Mg and FEr Mg. Effects of Mg repletion on these variables at monthly interval are as follows: (Table)TableIn hypoMg patients Mg repletion increases serum and ion Mg but no effect was seen on RBC Mg, U.Mg, FE Mg and ion calcium showed increased trend but did not reach statistical significance. We conclude that serum and ionized Mg values are well correlated and should be used to screen for hypoMg and for Mg therapy in potentially hypoMg renal transplant patients. U.Mg may continue to demonstrate reduced excretion despite of Mg repletion and may not be used as guide for adequate Mg repletion.