Seasonal variations of blood pressure in hemodialysis and renal transplant recipients.

Seasonal variations influence blood pressure (BP) in healthy persons. Its effects on BP in renal replacement therapy, especially after renal transplantation (RTX), have not been proven clearly. We studied 80 stable RTX and 82 hemodialysis (HD) patients for 4 years. Systolic and diastolic BP, body weight (BW), cholesterol (Chol), triglyceride (TG), fasting blood sugar (FBS), blood urea nitrogen (BUN), and creatinine (Cr) were measured monthly. Their relationship with environmental temperature and humidity changes were assessed by Pearson tests and Fourier analysis. Ambient temperature and humidity were between 2.5 degrees C to 25.4 degrees C and 68% to 31% in the winters versus summers, respectively. The mean systolic BP in HD patients was 144 +/- 18 mm Hg and 140 +/- 15 mm Hg during the winter and summer, respectively (P =.004). For the RTX recipients, it was 133 +/- 12 mm Hg in winter and 128 +/- 19 mm Hg in summer (P <.001). The decrement in diastolic BP in warmer seasons was even more significant than that in systolic BP in both HD and RTX groups. Also, BW in summer was significantly lower than winter among HD (61.1 +/- 10 kg vs 63.2 +/- 9 kg; P <.001) and RTX (64.4 +/- 8 kg vs 65.6 +/- 8.4; P <.001) groups. Serum Chol, TG, and FBS did not change significantly during summer and winter in the both groups. Among RTX recipients, BUN level was greater in summer than winter seasons (24.2 +/- 15 vs 39.4 +/- 20 mg/dL; P =.01), but serum Cr did not differ. The degree of humidity did not correlate with BP, BW, or the above biochemical markers. We conclude that BP and BW are decreased in warmer seasons in both HD and RTX patients. The changes are not accompanied by changes in biochemical markers except for BUN in RTX patients.