Acute and long-term changes in plasma levels of atrial natriuretic factor in patients with renal replacement therapy.

In 14 patients on hemodialysis who received kidney grafts from living related donors, plasma levels of immunoreactive atrial natriuretic factor (Ir-ANF) were determined in a sequence covering the last hemodialysis treatment, the day of transplantation, and a follow-up period of 6-12 months. The geometric mean value before dialysis was 196 pg/ml, the range 32-634. Weight loss during dialysis was 1.5 +/- 1.1 kg (mean +/- SD), but only a nonsignificant reduction in Ir-ANF levels occurred. On the day of transplantation, plasma Ir-ANF levels increased from 143 pg/ml before to 391 post-transplantation (P = 0.02, n = 12), probably in response to deliberate volume expansion. Post-transplant Ir-ANF levels correlated significantly to diuresis during the first 24 h, which ranged from 3.7 to 17.81 (mean 6.6; r = 0.65, P = 0.02). On day 2, mean 24 h diuresis decreased to 3.3 +/- 1.41. Most patients had reached their true dry weight by day 5, but Ir-ANF levels remained high, the geometric mean being 180 pg/ml. During further follow-up and preserved graft function (GFR range 34-88 ml/min per 1.73 m2 body surface area), Ir-ANF levels declined to a geometric mean of 63 pg/ml by 2-6 months and to 36 at 12 months post-transplant. We conclude that plasma Ir-ANF levels are chronically elevated in patients with chronic renal failure but may be further stimulated by acute overhydration. Transplanted kidneys initially respond to the increased levels but adapt within a day. Even with good graft function, normalization of plasma Ir-ANF requires several weeks or months.