HYPOMAGNESEMIA IN RENAL-TRANSPLANT PATIENTS - IMPROVEMENT OVER TIME AND ASSOCIATION WITH HYPERTENSION AND CYCLOSPORINE LEVELS

Hypomagenesemiais frequently encountered early after kidney transplant ation, especially in patients receiving cyclosporine (CsA). However, t here have been no studies addressing the natural history of this disor der in adult transplant recipients. We conducted this investigation to study the change in the prevalence of hypomagnesemia over time in ren al transplant patients as well as to determine the factors associated with this change. Three patient groups were studied: 24 CsA-treated pa tients followed longitudinally at 1, 3 and 6 months post-transplant (G roup 1a, 1b, 1c); 33 CsA-treated patients at least 2 years post-transp lant (Group 2; mean follow-up 55+/-25 months); and 31 non-CsA-treated patients at least 2 years post-transplant (Group 3; mean follow-up 132 +/-57 months). The following parameters were monitored: serum and urin e magnesium levels; serum potassium; creatinine clearance; fractional excretion of magnesium; and trough CsA levels. In group 1 patients, lo ngitudinal follow-up showed a significant linear trend for improvement in the serum magnesium over time (1.6+/-0.3, 1.7+/-0.2, 1.8+/-0.2 mg/ dl; p=0.0015) as well as a decline in the whole blood CsA level (316+/ -103, 251+/-82, 194+/-67 ng/ml; p=0.0015) at 1, 3 and 6 months, respec tively. The serum magnesium was significantly higher in group 2 (1.8+/ -0.2 mg/dl) compared with group 1a (1.6+/-0.2 mg/dl; p=0.0024), but di d not achieve the level observed in the non-CsA-treated group-3 patien ts (2.0+/-0.2 mg/di; p<0.00004, group 2 vs 3). While the fractional ex cretion of magnesium showed a decreasing trend over time in CsA-treate d patients, this was not statistically significant. However, the fract ional excretion of magnesium was significantly lower in group 3 (6.4+/ -2.4%) compared with groups 1a (8.7+/-3.9; p= 0.009) and 1b (8.7+/-3.9 ; p=0.01). Hypomagnesemia was noted in 11% and 49% p=0.001) of patient s who were normotensive and hypertensive, respectively. Furthermore, o f patients requiring 0, 1 or greater than or equal to 2 antihypertensi ve medications, 12, 45 and 58% (p=0.001) respectively, were noted to h ave hypomagnesemia. In our study, hypomagnesemia improves with time in CsA-treated patients, but not to the level of non-CsA treated patient s. The improvement in the serum magnesium levels in CsA-treated patien ts appears to be related to declining CsA levels. The hypomagnesemia i s the result of urinary magnesium loss. Finally, hypertension and the severity of hypertension are associated with low serum magnesium level s.