Blood pressure and sex differences

Blood pressure and sex differences

The leading cause of death globally is heart disease and hypertension is a risk factor for heart disease. Hypertension involves many organs in the body and is considered a modifiable risk factor for heart disease. For decades, the best practice guidelines have referred to the upper range of blood pressure readings (the systolic blood pressure) as being 120 mm Hg for the normal upper limit. Accordingly, cardiovascular disease risk is increased from a systolic blood pressure above 120 mm Hg (1). High blood pressure is often associated with few symptoms, but when someone has high blood pressure the heart and arteries of the heart are under more strain. Often referred to as ‘the silent killer’ because many people with high blood pressure do not know they have it until it has progressed. 

Hypertension is a medical condition that affects over a billion people in the world today and only 1/5 of those affected have the problem under control (2).  There is also limited information about potential sex differences to determine normal ranges for men and women. The Guidelines for the Prevention, Detection, Evaluation and Management of High Blood Pressure in Adults was released in 2017 (3). The significant change to our understanding of the management of hypertension was a change (a reduction) in the threshold of the systolic blood pressure (SBP) and diastolic blood pressure (DSP) required to be hypertensive.

A recent study(1) determined some sex differences in cardiovascular risk began at lower SBP in women compared to men where risk for women was at the threshold of SBP 120-129 mm Hg compared to men with a higher SBP threshold of 140-149 mm Hg. These differences could be related to differences in the anatomy (the study of the body) and physiology (the study of how the body works) of women and men. It has been established that men were likely more hypertensive than women prior to the onset of menopause, after this time the prevalence of hypertension in women relative to men equaled and then exceeded that seen in men.

The differences in the anatomy between the sexes has been known for many years, but to summarize, the body composition of male bodies have typically more muscle and bone mass where women’s bodies typically have more percentage of fat than males. In the cardiovascular system the main differences are the size of the cardiac (heart) chambers and volume of circulating blood where in women these are smaller and lower respectively (4)

It is important to note that hypertension research has not historically been separated by sex, and to better understand these differences more is yet to be discovered. These sex differences mean that more research that includes women  as study participants is needed to inform sex specific differences to inform healthcare professionals regarding high blood pressure assessment and management. 

 

References

  1. Ji, H., et al (2021). Sex Differences in Blood Pressure Associations With Cardiovascular Outcomes. Circulation143(7), 761-763.
  2. WHO (2021) Hypertension accessed from https://www.who.int/health-topics/hypertension/#tab=tab_1
  3. Whelton, P. K.,et al. (2018). Wright JT Jr. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA Guideline for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines.
  4. Altavilla, G., et al (2017). Anthropometric, physiological and performance aspects that differentiate male athletes from females and practical consequences. Journal of Physical Education and Sport17, 2183-2187.