Diagnosing Hypertension: All You Need to Know

The diagnosis of hypertension is made by a specialist with the help of a blood pressure monitor or a test with an ABPM device. However, in some settings you can use laboratory or imaging tests. Find out the standard procedure for it.
Diagnosing Hypertension: All You Need to Know

Last update: 16 December, 2022

According to the World Health Organization (WHO), a person is considered to have high blood pressure when its values are equal to or greater than 140/90 mmHg. Because it rarely develops with symptoms, most people aren’t aware of the condition. Diagnosing hypertension is carried out with the help of special devices and some additional tests.

This condition is related to kidney and cardiovascular problems, so an early diagnosis is helpful in order to avoid unpleasant complications. All adults should know their blood pressure values on a recurring basis, preferably with the mediation of a qualified specialist.

Hypertension diagnostic tests

Diagnosing hypertension requires diverse equipment.
The measurement of blood pressure can be carried out both in a timely manner and over a period of time, using special devices.

Traditionally, when diagnosing hypertension, we use a blood pressure cuff, also known as a blood pressure monitor or sphygmomanometer. The cuff externally compresses the patient’s arm or wrist and then releases pressure to measure the systolic rate (when the heart contracts) and the diastolic rate (when it relaxes).

For an objective diagnosis, the doctor must repeat the test several times, and then again over the course of two to three weeks. When at least three high blood pressure values have been obtained with an interval of 7 days, then it is understood that the person is suffering from hypertension. However, this may require confirmation.

The reason is that it’s also possible to have white coat hypertension. Anxiety and fear can raise stress levels in a doctor’s clinic, and so results are always conditional. For a more accurate assessment, the specialist will recommend an ABPM device test or home blood pressure monitoring.

Ambulatory blood pressure monitoring (ABPM)

Ambulatory blood pressure monitoring, better known as ABPM, is a test that measures blood pressure values over 24 or 48 hours. It consists of a small device that is automatically activated every 20 or 30 minutes to perform the measurement. This carries a memory with a register that accounts for high values.

Its usefulness is that it allows us to know how blood pressure behaves when the patient carries out their daily activities. Research has confirmed that it’s a safe, easy, and practical method.

Home blood pressure monitoring

An alternative to the previous test – it allows you to obtain longer values but with larger intervals. Its disadvantage is that it doesn’t measure values when people are carrying out activities, nor when they sleep. Even so, it’s a solid test to turn to when in doubt.

In general, a digital blood pressure monitor is used to measure these values. The patient makes the measurements based on the intervals suggested by the doctor, then transmits the information for further analysis. The evidence shows its effectiveness, although people must be taught carefully how to perform the procedure to prevent incorrect results.

Based on these clinical measurements, the physician should have enough information to diagnose high blood pressure. The American Heart Association divides it into 2 stages:

  • Stage 1 hypertension: This ranges from 130/139 mmHg for systolic pressure to 80/89 mmHg for diastolic.
  • Stage 2 hypertension: Systolic pressure values are equal to or greater than 140 mmHg and equal to or greater than 90 mmHg for diastolic.

Based on this, the specialist can now prescribe some treatment. If doubts remain, the specialist can use additional tests.

Laboratory tests for diagnosing hypertension

If you choose to perform laboratory tests, it’s usually because the doctor suspects secondary hypertension. This is when a primary condition causes the increase in blood pressure, often located in the heart, kidneys, or endocrine system.

As it’s estimated that 10% of hypertension cases are secondary, there’s a protocol for its diagnosis. This consists of performing the following tests:

  • Uroanalysis: By means of this test, it can be determined if the tension is caused by drug intake or by the presence of diabetes.
  • Blood tests: Used to assess kidney function, although they can also be used to assess levels of blood glucose, cholesterol, triglycerides, electrolytes, thyroid, and more.

If all the values are in order, the specialist can opt for imaging tests before ruling out the hypothesis of secondary hypertension.

Imaging tests for high blood pressure

Magnetic resonance imaging is a method used for the diagnosis of secondary arterial hypertension
These tests allow detecting structural problems in certain organs related to the control of blood pressure.

These are less frequent than a classic diagnostic test or a laboratory test, although they’re the last resort to try to rule out the primary causes of the disease. The most frequently used tests are the following:

  • Echocardiogram: Through images produced by waves, the presence of cardiac anomalies can be determined. It allows you to see the heart in motion to analyze its dynamics.
  • CT or MRI scan: Both are used to rule out the presence of a tumor in the adrenal glands, known as a pheochromocytoma. They’re not used as often as the previous ones, although in certain contexts they can be helpful.

If, after carrying out all these tests for diagnosing hypertension, the specialist can’t find any correlation, then he will proceed to rule out hypertension as a secondary phenomenon. If some anomalies is perceived, then the answer can be found in a differential diagnosis.

Differential diagnosis of hypertension

Many diseases or conditions can be linked to high blood pressure. Among the most common we highlight the following:

  • Renal failure: A paradoxical relationship between hypertension and renal failure has been demonstrated. Each of these can cause the other condition, and so it’s one of the first things that the cardiologist must rule out. It can be acute or chronic and is treated based on its severity.
  • Medications or drugs: The side effects of some drugs can cause high blood pressure, as well as using recreational drugs. The patient should inform the physician of changes in drug intake in order to look for a related pattern.
  • Hypothyroidism: Many studies and research have suggested hypothyroidism as a cause of secondary hypertension. Abnormalities can be detected through a blood test and by the presence of other symptoms such as weight gain, sweating, and anxiety.

If some of these conditions are confirmed, the respective treatment will be started. If no cause is found, then the diagnosis will be hypertension – in one of its grades or types – due to a primary cause.

The specialist will then proceed to find the best way to control levels based on drug therapy and lifestyle changes.

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