Lack of seasonal variation in blood pressure in patients on hemodialysis in a North American Center

Seasonal variation in blood pressure in patients undergoing hemodialysis in Europe has recently been described. If confirmed, this has important therapeutic, research, and epidemiological implications. Ail normotensive patients not administered antihypertensive drugs in our unit were studied. Predialysis blood pressures were measured before each dialysis treatment over two 2-month periods, January through February and July through August, in Winnipeg, Canada, a city with one of the most extreme seasonal temperature variations in North America. No difference in blood pressures was found between summer and winter (141 +/- 5/75 +/- 2 versus 140 +/- 4/74 +/- 2 mm Hg; P = not significant). Average daily temperatures were -16 degrees C in winter and 23 degrees C in summer. Interdialytic weight gain was the same in both groups. In conclusion, season has no effect on blood pressure in hemodialysis patients in a North American center. Reported seasonal changes in blood pressure in Europe may be related to nonclimatic factors. (C) 2000 by the National Kidney Foundation, Inc.