Haider Nawaz Naqvi, Mirza Naqi Zafar, Amna Hussain, Syed Ali Anwar Naqvi, Adibul Hassan Rizvi.
Cyclosporine induced Nephrotoxicity in renal transplant recipients: clinical significance of fractional excretion of Sodium, Potassium and Magnesium.
J Pak Med Assoc Jan ;55(4):161-4.

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 day1 was 3.1+1.3 mg/dl and declined to 1.6+1.2 on day10. 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 day10. 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 day1, 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 day10. 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 day10, FENa+ 3.7+ 2.7%, FEK+ 20+15% and FEMg2+ 15+8% (p<0.05). In the group B, day 1 and day10 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 (JPMA 55:161;2005).

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