Blood pressure changes throughout the day and varies from person to person. Various factors affect blood pressure, including your body position, breathing rhythm, stress level, physical activity, medications, what you eat or drink, and the time of the day (blood pressure is usually lowest at night when you sleep and rises when you wake up). In healthy individuals, your body responds and adapts to these changes to keep your blood pressure within a normal range. This ensures that vital organs, such as your brain and kidneys, receive a constant blood flow and nutrient supply.
Your blood pressure is considered high when you have consistent systolic readings of 140 mm Hg or higher or diastolic readings of 90 mm Hg or higher. Based on research, your doctor may also consider you to have high blood pressure if you are an adult or child age 13 or older who has consistent systolic readings of 130 to 139 mm Hg or diastolic readings of 80 to 89 mm Hg and you have other cardiovascular risk factors.
A blood pressure reading contains two numbers: systolic pressure and diastolic pressure. Systolic pressure is the top or first number in your blood pressure reading; it indicates the pressure within your arteries when your heart pumps out blood. Diastolic pressure is the bottom number, and shows the pressure in your arteries while your heart is filling with blood.
Elevated blood pressures in the medical setting may not necessarily reflect the individuals real status. "White coat hypertension" describes a patient whose blood pressure is elevated because of the stress of the visit to the doctor or other healthcare professional, and the worry that their blood pressure might be elevated. Repeated blood pressure checks at the doctor's office or the use of a home blood pressure monitoring device may be used to confirm that you have high blood pressure.
Hypertension results from a complex interaction of genes and environmental factors. Numerous common genetic variants with small effects on blood pressure have been identified as well as some rare genetic variants with large effects on blood pressure. Also, genome-wide association studies (GWAS) have identified 35 genetic loci related to blood pressure; 12 of these genetic loci influencing blood pressure were newly found. Sentinel SNP for each new genetic locus identified has shown an association with DNA methylation at multiple nearby CpG sites. These sentinel SNP are located within genes related to vascular smooth muscle and renal function. DNA methylation might affect in some way linking common genetic variation to multiple phenotypes even though mechanisms underlying these associations are not understood. Single variant test performed in this study for the 35 sentinel SNP (known and new) showed that genetic variants singly or in aggregate contribute to risk of clinical phenotypes related to high blood pressure.
The cause for hypertension is not always known, although it can develop as a result of other health conditions including: sleep apnea, kidney problems, and thyroid issues. Beyond chronic health conditions, risk factors for hypertension include age, the amount of salt you eat, being overweight or obese, using tobacco, drinking excessively, not exercising, and having too little potassium in your diet.
If your blood pressure readings are consistently high, you and your doctor will probably discuss treatment strategies. Treatment for high blood pressure often begins with lifestyle changes such as a weight loss and exercise program as well as a low sodium diet. In fact, the AHA recommends adopting these strategies as a means of preventing the development of high blood pressure and heart disease. If these strategies are not successful in lowering your blood pressure, medications may be recommended.
As you get older, high blood pressure, especially isolated systolic hypertension, is more common and can increase your risk of serious health problems. Treatment, especially if you have other medical conditions, requires ongoing evaluation and discussions with your doctor to strike the best balance of reducing risks and maintaining a good quality of life.