CIRCADIAN-RHYTHM OF GLOMERULAR-FILTRATION RATE IN PATIENTS AFTER KIDNEY-TRANSPLANTATION

Within 6 months of a kidney transplantation the graft can be regarded as an organ deprived of its innervation. We analysed whether the trans planted kidney has a diurnal rhythm of its glomerular filtration rate (GFR) similar to the GFR rhythm that has been demonstrated in normal i ndividuals and in patients with nephrotic syndrome. GFR was measured b y inulin clearances every 3 h during 1 day of bed-rest and identical f ood and fluid intake per 3 h in seven patients, 4-7 months after a suc cessful kidney transplantation, and in 10 healthy volunteers. Similar to these healthy subjects, a normal circadian rhythm of GFR was detect ed in all but one patient with a maximum of 57 (range 45-82) ml/min in daytime, a minimum of 47 (range 36-70) ml/min during the night and a relative amplitude of 21 (range 10-41)%. The circadian rhythm of GFR w as absent in the patient with the lowest value of GFR (39 ml/min). In conclusion, GFR has a circadian rhythm in patients studied within 6 mo nths of a kidney transplantation, despite the absence of renal innerva tion.