Course of glomerular filtration rate after renal transplantation and the influence of hypertension.

INTRODUCTION: A gradual decline in the glomerular filtration rate (GFR) is a general problem in patients after renal transplantation that may be due to several factors.
METHODS: The glomerular filtration rate (GFR) was estimated using the corrected Schwartz formula in 16 pediatric renal transplant recipients over a period of 5 years post-transplant. Several potential risk factors for graft outcome were analyzed. The mean age of the patients (8 female, 8 male) at the time of transplantation was 11.1 years (range: 2.7-17.3). All patients received a cadaveric renal graft for the first time. Immunosuppression consisted of cyclosporine in combination with steroids in all children treated; 3 patients received azathioprine in addition. Blood pressure (BP) was monitored regularly and its extent was expressed by an antihypertensive treatment (AHT) score.
RESULTS: At the end of the first post-transplant year the mean GFR was 88 +/- 24 ml/min/1.73 m2. During the following 4 years the GFR declined to 68 +/- 29 ml/min/1.73 m2 representing an overall GFR loss of 20 ml/min/1.73 m2 (23%). With regard to the GFR loss, 2 groups could be distinguished. The first group of 7 patients showed a significant GFR decrease from 89 +/- 26 to 49 +/- 27 ml/min/1.73 m2 (p = 0.0025), whereas the second group of 9 patients had a relatively constant GFR during the 5 years (87 +/- 26 and 83 +/- 24 ml/min/1.73 m2). In each group, two acute rejections were observed in the first post-transplant year. Blood pressure, expressed by an AHT score, increased in Group 1 moresso than in Group 2 during the 5 years.
CONCLUSION: During the course of a 5-year period post-transplant the GFR declined significantly in 7 of 16 patients. One of the factors responsible for GFR loss is probably the increase in blood pressure.