How is high blood pressure diagnosed?
A one-off blood pressure reading that is high does not mean that you have high blood pressure (hypertension). Your blood pressure varies throughout the day. It may be high for a short time if you are anxious, stressed, or have just been exercising.
You have high blood pressure if you have several blood pressure readings that are high, taken on different occasions, and when you are relaxed.
If one reading is found to be high, it is usual for your doctor or nurse to advise a time of observation. This means several blood pressure checks at intervals over time. The length of the observation period varies depending on the initial reading and whether you have other health risk factors.
For example, say a first reading was mildly high at 145/89 mm Hg. If you are otherwise well then a period of several weeks of observation may be advised. This may involve several blood pressure measurements over the following few weeks. You may be given a machine to monitor blood pressure while you are going about doing your everyday activities (ambulatory monitoring). You may be given (or asked to buy) a machine to measure your blood pressure at home (home monitoring). One reason this may be advised is because some people become anxious in medical clinics. This can cause the blood pressure to rise. (This is often called white coat hypertension.) Home or ambulatory monitoring of blood pressure may show that the blood pressure is normal when you are relaxed.
The observation period is also a good time to change any lifestyle factors that can reduce blood pressure. If the blood pressure readings remain high after an observation period then medication may be advised, depending on your risk factors.
However, if you have diabetes, or have recently had a heart attack or stroke, you may be advised to have blood pressure checks fairly often over the following week or so. Also, treatment with medication is usually considered at an earlier stage if the readings remain high.
Do I need any further tests?
If you are diagnosed as having high blood pressure (hypertension) then you are likely to be examined by your doctor and have some routine tests which include:
- A urine test to check if you have protein or blood in your urine.
- A blood test to check that your kidneys are working normally and to check your cholesterol level and sugar (glucose) level.
- A heart tracing, called an electrocardiogram (ECG).
The purpose of the examination and tests is to:
- Rule out (or diagnose) a secondary cause of high blood pressure, such as kidney disease.
- Check to see if the high blood pressure has affected the heart.
- Check for other risk factors such as a high cholesterol level or diabetes.
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Further reading & references
- Hypertension: management of hypertension in adults in primary care; NICE Clinical Guideline (August 2011)
- Guidelines for the management of arterial hypertension; ESH/ESC Clinical Practice Guidelines, European Society of Cardiology (2013)
- He FJ, Li J, Macgregor GA; Effect of longer term modest salt reduction on blood pressure: Cochrane systematic review and meta-analysis of randomised trials. BMJ. 2013 Apr 3 346:f1325. doi: 10.1136/bmj.f1325.
- Description of the DASH (Dietary Approaches to Stop Hypertension) Eating Plan; National Institutes of Health
- Lipid modification - cardiovascular risk assessment and the modification of blood lipids for the prevention of primary and secondary cardiovascular disease; NICE Clinical Guideline (July 2014)
- Ettehad D, Emdin CA, Kiran A, et al; Blood pressure lowering for prevention of cardiovascular disease and death: a systematic review and meta-analysis. Lancet. 2016 Mar 5 387(10022):957-67. doi: 10.1016/S0140-6736(15)01225-8. Epub 2015 Dec 24.
- Alcohol Guidelines Review – Report from the Guidelines development group to the UK Chief Medical Officers; Department of Health, January 2016
- 2016 European Guidelines on cardiovascular disease prevention in clinical practice; European Society of Cardiology (2016)
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. Patient Platform Limited has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.