ABSTRACT
Evaluation of fractional excretion of Sodium, Potassium and Magnesium as indicators of cyclosporine [CsA] toxicity in de-novo renal transplant recipients. A prospective study was conducted on 59 live related renal allograft recipients. Fractional excretion [FE] of sodium [Na[+]], potassium [K+] and magnesium [Mg[2+]] 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. The mean creatinine on dayl was 3.1 + 1.3 mg/dl and declined to 1.6+1.2 on daylO. FE of Na[+], K[+] ; and Mg[2+] 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 dayl, FENa+, FEK+ and FEMg[2+] 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[+] 1 5+8%, FEK+ 36+24% and FEMg[2+] 21 + 10% [p<0.0001] and on day 10, FENa[+] 3.7+ 2.7%, FEK+ 20+15% and FEMg[2+] 15+8% [p<0.05]. In the group B, day 1 and day10 levels were FENa[+] 6+3%, FEK[+]26+13% and FEMg[2+] 7+2.8% and FENa[+] 1.2+0.7%, FEK+ 4.2+0.5%, FEMg[2+] 7+4% respectively. CsA levels and AUC did not correlate with CsA toxicity. FE of magnesium is a useful marker of CsA toxicity independent of CsA blood levels. FE studies can supplement renal biopsy findings