Correspondence

Seasonal Changes in Blood Pressure in Patients Undergoing Hemodialysis

N Engl J Med 1999; 340:965-966March 25, 1999

Article

To the Editor:

In their impressive four-year study of blood pressure in 53 patients undergoing dialysis, Argilés et al. (Nov. 5 issue)1 found that the patients' blood pressures were higher in the winter than in the summer and that this variation was not associated with any seasonal variation in weight gain between dialysis sessions. Was there an increase in the intake of cold remedies, nonsteroidal antiinflammatory drugs, caffeine-containing beverages, or alcohol in the winter, all of which, in large amounts, may increase blood pressure? Data on these and other lifestyle factors might be helpful in understanding these interesting results.

Kevin E. Vitting, M.D.
St. Joseph's Hospital and Medical Center, Paterson, NJ 07503

1 References

1. 1

   Argiles A, Mourad G, Mion C. Seasonal changes in blood pressure in patients with end-stage renal disease treated with hemodialysis. N Engl J Med 1998;339:1364-1370
   Full Text | Web of Science | Medline

To the Editor:

Argilés et al. ascribe the wintertime elevations and summertime reductions in blood pressure to changes in temperature and humidity. However, an alternative possibility is that the changes were mediated by seasonal variations in exposure to ultraviolet radiation. In Montpellier, France, where the study was conducted, skin photosynthesis of previtamin D should be negligible in the winter and should be associated with measurable decreases in serum 25-hydroxyvitamin D concentrations and increases in serum parathyroid hormone concentrations1 — changes that have been implicated in the pathogenesis of hypertension. In patients with essential hypertension and patients with end-stage renal disease who are being treated with dialysis, the blood pressure falls in response to a course of ultraviolet radiation, and the fall is associated with an increase in serum 25-hydroxyvitamin D concentrations and a decrease in serum parathyroid hormone concentrations.2,3 These findings suggest that differences in the intensity of ultraviolet radiation may contribute to the seasonal variations in blood pressure noted in the patients with end-stage renal disease studied by Argilés et al.

Stephen G. Rostand, M.D.
University of Alabama at Birmingham, Birmingham, AL 35294-0007

3 References

1. 1

   Webb AR, Kline L, Holick MF. Influence of season and latitude on the cutaneous synthesis of vitamin D₃: exposure to winter sunlight in Boston and Edmonton will not promote vitamin D₃ synthesis in human skin. J Clin Endocrinol Metab 1988;67:373-378
   CrossRef | Web of Science | Medline

2. 2

   Krause R, Bennhold I, Britzke K, et al. Reduction of cardiac risk factors in coronary and hemodialysis patients after UV(B) therapy. In: Holick MF, Jung EG, eds. Biologic effects of light 1995: proceedings of a symposium, Atlanta, October 9–11, 1995. Berlin, Germany: Walter de Gruyter, 1996:70-2.
   

3. 3

   Krause R, Buhring M, Hopfenmuller W, Holick MF, Sharma AM. Ultraviolet B and blood pressure. Lancet 1998;352:709-710
   CrossRef | Web of Science | Medline

Author/Editor Response

The authors reply:

To the Editor: Drs. Vitting and Rostand both provide interesting insights in attempting to explain our findings that blood-pressure cycles follow the seasons of the year. Indeed, our analyses of the meteorologic data revealed significant correlations between blood pressure and temperature and humidity but did not establish causality in either direction between these measurements. Therefore, it is still important to search for the factors mediating the changes in blood pressure.

In response to Dr. Vitting's comments, a poll of 36 patients currently being treated in our dialysis unit revealed that they drink an average of 2 cups of coffee (range, 0 to 10) and practically no tea (only 3 patients drink tea) each day, and that neither coffee nor alcohol consumption varies seasonally. Similarly, our prescription of nonsteroidal antiinflammatory drugs does not follow a seasonal pattern, but we do not know about the patients' use of cold remedies available without a prescription.

Dr. Rostand suggests that a decrease in exposure to the sun during the winter increases blood pressure by decreasing vitamin D₃ formation and increasing parathyroid hormone secretion. Although Montpellier and Boston have similar latitudes, the daytime temperatures during the winter are considerably higher in Montpellier, allowing more outdoor activity and greater exposure to the sun; in addition, most patients in our unit receive supplemental alfacalcidol. Furthermore, among 21 patients who underwent dialysis in our unit for more than 12 months and who did not receive alfacalcidol, serum parathyroid hormone concentrations, determined quarterly during 1995 and 1996, were lowest in the summer of 1995 and highest in the summer of 1996 (mean [±SD], 48±9 and 94±17 pg per milliliter, respectively). This variation does not suggest that parathyroid hormone had a role in the summer–winter variations in blood pressure that we found, albeit in a different group of patients.

We are investigating the possible role of the variations in predialysis serum sodium concentrations, water intake, and dietary factors in the seasonal changes in blood pressure.

Àngel Argilés, M.D., Ph.D.
Association pour l'Installation à Domicile des Epurations Rénales, 34192 Montpellier, CEDEX 5, France

Georges Mourad, M.D.
University Hospital Lapeyronie, 34295 Montpellier, France

Citing Articles (2)

Citing Articles

1. 1

   Jinshyun Ruth Wu-Wong. (2007) The potential for vitamin D receptor activation in cardiovascular research. Expert Opinion on Investigational Drugs 16:4, 407-411
   CrossRef

2. 2

   Angel Argiles, Ronan Lorho, Marie-Francoise Servel, Guillaume Chong, Peter G. Kerr, Georges Mourad. (2004) Seasonal modifications in blood pressure are mainly related to interdialytic body weight gain in dialysis patients. Kidney International 65:5, 1795-1801
   CrossRef