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Abstract: FR-PO299

Tacrolimus Trough Levels and Risk of Hypomagnesemia in Renal Transplant Recipients

Session Information

Category: Fluid and Electrolytes

  • 902 Fluid and Electrolytes: Clinical

Authors

  • Gomes Neto, Antonio, University Medical Center Groningen, Groningen, Netherlands
  • Schutten, Joëlle C., University Medical Center Groningen, Groningen, Netherlands
  • Eisenga, Michele F., University Medical Center Groningen, Groningen, Netherlands
  • Sanders, Jan-Stephan, University Medical Center Groningen, Groningen, Netherlands
  • Berger, Stefan P., University Medical Center Groningen, Groningen, Netherlands
  • De Borst, Martin H., University Medical Center Groningen, Groningen, Netherlands
  • Navis, Gerjan, University Medical Center Groningen, Groningen, Netherlands
  • Bakker, Stephan J.L., University Medical Center Groningen, Groningen, Netherlands
Background

Magnesium (Mg) is the 2nd most abundant intracellular cation essential to neurochemical transmissions and many enzyme activities. Hypomagnesemia (hypoMg) is a risk factor for cardiovascular and mineral bone disease and in renal transplant recipients (RTR), Tacrolimus (Tac) use is associated with higher risk of hypoMg. However, it is unknown whether Tac trough levels further contributes to the risk of hypoMg. We aimed to investigate the association between Tac use and hypoMg in a large cohort of RTR.

Methods

For this study, we used data from the Transplantlines Biobank and Cohort Study comprising RTR with a functioning graft ≥1 year post-transplantation. Plasma Mg and Tac trough levels were measured using routine laboratory procedures. HypoMg was defined as a Mg level <1.7 mg/dL. Linear and logistic regression were used to assess the association of Tac use with plasma Mg and hypoMg, respectively. In additional analyses, we analyzed whether Tac trough levels were associated with plasma Mg and hypoMg in Tac users.

Results

We included 614 RTR (mean age 56±13 years; 59.2% male) at a median of 4.7 [1.0 - 11.7] years posttransplantation. Mean eGFR was 50±17 ml/min/1.73m2 and mean plasma Mg was 1.8±0.2 mg/dL. Of the total population, 170 (28%) RTR had a hypoMg and 378 RTR used Tac with a mean trough level of 5.8±1.8 ug/L. In linear regression analysis, Tac use was associated with lower plasma Mg (β -0.17 [95%CI -0.21;-0.12], p < 0.001), independent of age, sex, time after transplantation and eGFR. Similarly, in logistic regression analysis Tac use was independently associated with higher risk of hypomagnesemia (OR 4.5 [95%CI 2.6;7.8], p < 0.001). Within Tac users, Tac trough levels were strongly associated with lower plasma Mg (β -0.04 [95%CI -0.05 ; -0.03], p < 0.001) and higher risk of hypoMg (OR 1.4 [95%CI 1.2 ; 1.6], p < 0.001), independent of potential confounders.

Conclusion

HypoMg occurs in approximately 28% of RTR. Tac use is associated with a > 4 times greater risk of hypoMg. Importantly, we identified a dose-response effect between higher Tac trough levels and lower plasma Mg in Tac users. These results suggest that reducing Tac trough levels may be an effective treatment strategy for hypoMg in RTR treated with Tac.