The impairment of true glomerular filtration rate in long-term cyclosporine-treated pediatric allograft recipients

We performed indium-111-DTP A plasma clearance studies in 61 pediatric kidney and liver recipients treated with cyclosporine to compare true glomerular filtration rate with calculated GFR (cGFR). The mean true GFR of 61.9±36.6 ml/min/1.73 m² indicated renal impairment. The mean cGFR of 85.2±22.4 ml/min/1.73 m2 was significantly higher (PcO.OOl), and overestimated GFR by 38%. cGFR alone did not accurately reflect the degree of renal dysfunction. A group of 48 pediatric orthotopic liver transplant recipients was studied in more detail: 73% of these patients had a true GFR <70 ml/min/1.73 m2, while 85% had a true GFR below 90 ml/min/1.73 m2, the lower limit for normal GFR in children. The mean true GFR for patients treated more than 24 months with CsA was lower (P = 0.02) than patients treated with CsA for 12 to 24 months. OLT patients with normal true GFR (>90 ml/ min/1.73 m2) had significantly lower plasma CsA levels, and 50% of patients with a true GFR <50 ml/min/1.73 m2 had hypertension. There was no effect on true GFR of age, liver function, azathioprine use, or peritransplant treatment with other nephrotoxic drugs. We conclude that true GFR is significantly impaired in longterm CsA-treated allograft pediatric recipients. Calculations of GFR underestimate the degree of renal dysfunction. As patients treated >24 months had the lowest true GFRs, the fall in GFR may be progressive.