RESUMO
OBJECTIVE: Evaluation of fractional excretion of Sodium, Potassium and Magnesium as indicators of cyclosporine (CsA) toxicity in de-novo renal transplant recipients. METHODS: A prospective study was conducted on 59 live related renal allograft recipients. Fractional excretion(FE) of sodium (Na+), potassium (K+) and magnesium (Mg2+) were calculated on day 1, 3, 5 and 10 post transplant. Graft dysfunctions were evaluated by colour-Doppler, CsA levels and renal biopsy. Normal ranges were determined on 30 healthy subjects. RESULTS: The mean creatinine on day 1 was 3.1 +/- 1.3 mg/dl and declined to 1.6 +/- 1.2 on day 10. FE of Na+, K+ and Mg2+ were 12 +/- 9%, 34 +/- 20% and 13 +/- 10% respectively on day 1 and reduced to 2.2 +/- 2%, 11 +/- 14% and 11 +/- 14% on day 10. Of the 59 recipients, 38 (64%) had uneventful recovery (group A), 21(36%) had graft dysfunction [6 acute rejection (group B) and 15 either acute tubular necrosis or high CsA(group C)]. In group A, on day 1, FENa+, FEK+ and FEMg2+ were 5 +/- 4%, 24 +/- 12% and 6.6 +/- 3% respectively and these declined to 1.2 +/- 0.6%, 4.6 +/- 0.7% and 6 +/- 3% respectively on day 10. Compared to group A, group C had significantly high values on day 1, FENa+ 15 +/- 8%, FEK+ 36 +/- 24% and FEMg2+ 21 +/- 10% (p < 0.0001) and on day 10, FENa+ 3.7 +/- 2.7%, FEK+ 20 +/- 15% and FEMg2+ 15 +/- 8% (p < 0.05). In the group B, day 1 and day 10 levels were FENa+ 6 +/- 3%, FEK+ 26 +/- 13% and FEMg2+ 7 +/- 2.8% and FENa+ 1.2 +/- 0.7%, FEK+ 4.2 +/- 0.5%, FEMg2+ 7 +/- 4% respectively. CsA levels and AUC did not correlate with CsA toxicity. CONCLUSION: FE of magnesium is a useful marker of CsA toxicity independent of CsA blood levels. FE studies can supplement renal biopsy findings.
