Seasonal variation of blood pressure in children.

Seasonal blood pressure (BP) variation is mostly found between the summer and winter months. Guidelines for diagnosis and treatment of hypertension in children have not considered this variation until recently. This review aims to present an overview of seasonal BP variation in childhood along with potential underlying pathophysiological mechanisms and long-term implications as well as conclusions for future studies. In pediatric cohorts, seven studies investigated seasonal changes in BP. These changes amount to 3.4-5.9 mmHg (or 0.5-1.5 mmHg per - 1 °C difference in environmental temperature) in systolic BP with a peak in fall or winter. Potential mechanisms and mediators of seasonal BP variation include sympathetic activation of the nervous system with an increase of urinary and plasma norepinephrine levels in the winter season. Additionally, the physical activity among children and adolescents was inversely correlated with BP levels. Temperature sensitivity of BP and pediatric BP levels predict future systolic BP and target-organ damage. Therefore, cardiovascular events may even be long-term complications of seasonal BP variation in pediatric hypertensive patients. Overall, these data strongly suggest an important effect of ambient temperature on BP in children. Additional studies in pediatric cohorts are needed to define how best to incorporate such variation into clinical practice.