Home blood pressure on winter mornings could be exaggerated: A comparison with summer mornings

Purpose Self-measured blood pressure at home (HBP) is quite important for the management of hypertension. We hypothesized that winter HBP measured according to the recommendation of the guidelines, but not HBP measured inside bed before getting up, is elevated in response to cold ambient temperatures in winter. This study aimed to investigate differences in HBP measured before and after getting up in winter and summer.Methods: Hypertensive subjects whose blood pressure was stably controlled were enrolled (n = 46, 73 years). They were instructed to measure HBP while in bed just after waking (HBP-bed), in addition to the ordinary HBP measurement in the morning (HBP-morning) according to the guidelines. The mean value of HBP for 7 consecutive days before the day of a regular hospital visit was considered as the HBP of each subject, and characteristics of the winter and summer BPs were investigated.Results: HBP-morning was significantly higher (P < .001) in winter than in summer, but HBP-bed was lower in winter than in summer (P < .05). HBP-morning was significantly higher than HBP-bed in winter, while HBP-morning was not different from HBP-bed in summer, resulting in greater changes in HBP after getting up in winter than in summer (P < .0001). Changes in HBP after getting up were significantly correlated with serum creatinine levels and the urinary albumin-to-creatinine ratio.Conclusions: These findings imply that elevated HBP-morning in winter reflects the response of BP to cold after getting up. Seasonal profiles of HBPs before and after getting up should be noted in the management of hypertension.