Hypertension: Understanding your numbers and taking action

It’s called the “silent killer,” and that’s no exaggeration. High blood pressure affects nearly one in four Canadian adults, according to Statistics Canada data, and half of those affected are unaware of it. No pain, no outward signs, no clear warning. Blood pressure rises silently, year after year, while the arteries, heart, and kidneys take the brunt of it. World Hypertension Day, observed on May 17, provides an opportunity to take stock of what your numbers really mean and what concrete steps you can take.

What is blood pressure?

With every beat, your heart pumps blood through a network of arteries, veins, and capillaries that supply every organ in your body. Blood pressure measures the force that this blood exerts against the walls of your arteries. It is not a constant value. It naturally rises during physical exertion, stress, or after a cup of coffee, then drops again at rest. This cycle is normal. The problem arises when blood pressure remains chronically high—even at rest, even at night, and even for no apparent reason.

It is precisely this persistence that distinguishes hypertension from a simple, temporary spike. Arteries, which are designed to withstand fluctuations, eventually stiffen under constant pressure. Their walls thicken, their diameter narrows, and the heart’s ability to pump effectively gradually deteriorates.

Reading Your Numbers: Systolic vs. Diastolic

A blood pressure measurement always gives two values, expressed in millimeters of mercury (mm Hg), in the following format: 120/80, for example.

The first digit, the highest, is the systolic pressure. It indicates the force exerted on the arteries at the precise moment when the heart contracts and pumps blood out. It is the peak pressure that the arterial system must withstand with each heartbeat.

The second digit, the lowest one, is the diastolic pressure. It corresponds to the pressure that remains in the arteries between two contractions, when the heart is in its filling phase. A high diastolic number indicates that the arteries are under tension even at rest.

Both values are important. For a long time, more importance was placed on the systolic pressure in people over 60 and on the diastolic pressure in younger people. The current guidelines from Hypertension Canada take both into account in the overall risk assessment.

What are the thresholds for defining hypertension?

The Canadian guidelines published by Hypertension Canada are the references used by Quebec doctors. Here's how the values are interpreted in the office:

• Normal. Less than 120/80 mm Hg
• Elevated (prehypertension). 120-129 / less than 80 mm Hg
• Stage 1 hypertension. 130-139 / 80-89 mmHg
• Stage 2 hypertension. 140/90 mm Hg and above
• Hypertensive crisis (medical emergency). Over 180/120 mmHg

For home blood pressure monitoring, the thresholds differ slightly. Hypertension Canada considers an average of 135/85 mm Hg or higher, as measured at home, to be equivalent to high blood pressure measured in a doctor’s office. This distinction is important: blood pressure measured at the doctor’s office can sometimes be artificially higher due to the stress associated with the visit, a phenomenon known as white-coat hypertension.

For people with diabetes or chronic kidney disease, the targets are generally stricter—below 130/80 mm Hg. Your doctor will determine the appropriate target based on your individual profile.

Why High Blood Pressure Is Dangerous

Chronically high blood pressure damages blood vessels from the inside. Over the years, plaques of fat and calcium build up more easily on the weakened walls, gradually narrowing the lumen of the arteries. This process of atherosclerosis affects blood vessels throughout the body.

The most serious consequences are well-documented:

• Stroke. High blood pressure is the leading modifiable risk factor for stroke. It can cause a rupture or blockage of blood vessels in the brain.
• Myocardial infarction. Coronary arteries narrowed by atherosclerosis can become completely blocked, depriving the heart muscle of oxygen.
• Heart failure. A heart that is forced to pump against high resistance eventually enlarges and weakens, gradually losing its ability to meet the body's needs.
• Chronic kidney disease. The kidneys, which are highly sensitive to changes in blood pressure, are slowly damaged. High blood pressure is one of the two most common causes of end-stage kidney disease, along with diabetes.
• Hypertensive retinopathy. The small blood vessels in the retina can break or become blocked, threatening vision.

What makes this particularly insidious is that this damage builds up without warning. Most people with high blood pressure don’t experience any specific symptoms—no pain or discomfort that would prompt them to seek medical attention. That’s why regular monitoring remains the only reliable tool for early detection.

How to correctly measure your blood pressure

An improperly taken measurement can skew the diagnosis in either direction. There are a few basic rules to follow, whether in the doctor’s office or at home.

In a doctor's office. The doctor or nurse measures blood pressure after a few minutes of rest while sitting. If the reading is high, a second measurement is taken a few minutes later. Hypertension Canada recommends basing the diagnosis on at least two separate visits, unless the initial reading is very high.

Ambulatory blood pressure monitoring (ABPM). This is a portable device that the patient wears for 24 hours, which automatically measures blood pressure every 15 to 30 minutes. ABPM is particularly useful for detecting white-coat hypertension and masked hypertension, as well as for evaluating the effectiveness of treatment over the entire daily cycle, including at night.

Self-monitoring at home. Hypertension Canada recommends a clinically validated cuff, placed on the bare arm, at heart level. The recommended technique:

• Sit down and rest for 5 minutes before taking your measurement
• avoid coffee, tobacco, and physical exercise in the 30 minutes prior
• Take two consecutive measurements, one minute apart, in the morning and in the evening
• repeat for 7 consecutive days
• Calculate the average of the measurements (excluding the first day) to send to the doctor

Wrist cuffs are less reliable and generally not recommended for regular monitoring. An arm cuff validated by the British and Irish Hypertension Society or Hypertension Canada is the recommended standard.

Lifestyle habits to lower blood pressure

For mild to moderate hypertension, lifestyle changes can lower systolic blood pressure by 5 to 15 mm Hg, and sometimes even more, according to data compiled by Hypertension Canada. These lifestyle changes are recommended as a first-line treatment before considering medication, and they remain effective as a complementary treatment even when medication is prescribed.

The DASH Diet. The diet Dietary Approaches to Stop Hypertension is the dietary approach with the best-documented blood pressure-lowering effect. It emphasizes fruits, vegetables, whole grains, low-fat dairy products, legumes, and lean proteins, while limiting fatty meats, added sugars, and saturated fats.

Sodium reduction. The recommended daily intake is about 2,000 mg of sodium, which is equivalent to one teaspoon of salt. Most of the sodium in the Quebec diet does not come from the salt shaker, but from processed foods: deli meats, canned soups, prepared sauces, store-bought bread, and cheeses. Reading labels makes all the difference.

Physical activity. 30 to 45 minutes of moderate-intensity aerobic activity, five days a week, reduces systolic blood pressure by an average of 5 to 8 mm Hg. Brisk walking, cycling, swimming, and dancing all count. You don’t have to run a marathon.

Weight management. For every 10 kg of weight lost, systolic blood pressure decreases by 5 to 10 mm Hg in overweight individuals. The effect is proportional and occurs even before reaching what is considered an “ideal” weight.

Alcohol. Regular alcohol consumption is a well-established risk factor for high blood pressure. Hypertension Canada recommends limiting consumption to two drinks per day, with alcohol-free days each week. Reducing alcohol intake can lower blood pressure by 3 to 4 mm Hg.

Sleep and stress. Insufficient or fragmented sleep and chronic stress maintain prolonged activation of the autonomic nervous system, which keeps blood pressure elevated. Stress management (meditation, heart coherence, decompression activities) is among the overall recommendations.

Medical options

When lifestyle changes aren't enough, or when blood pressure is too high to wait, a doctor may prescribe medication. There are several classes of antihypertensive drugs, each with a different mechanism of action:

• angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs), which relax blood vessels
• calcium channel blockers, which reduce arterial constriction
• thiazide diuretics, which decrease fluid volume in circulation
• beta-blockers, which slow the heart rate and reduce the force of contraction

The choice of medication depends on the patient’s profile, comorbidities, age, and tolerance for side effects. There is no one-size-fits-all treatment. Gradual adjustment is often necessary before finding the optimal combination. This content is provided for informational purposes only: never self-medicate or change your treatment without your doctor’s approval.

The role of the family doctor in follow-up

High blood pressure is a chronic condition that requires long-term management. The family doctor plays a central role in this care, going far beyond simply prescribing medication.

Regular follow-up includes checking blood pressure at each visit, blood and urine tests to monitor kidney function and electrolyte balance, an electrocardiogram to detect thickening of the heart muscle, and an assessment of overall cardiovascular risk (including cholesterol, blood sugar levels, and lifestyle habits).

If blood pressure remains difficult to control despite two or three properly dosed medications, the doctor may refer the patient to a specialist (cardiologist or internist) to investigate secondary hypertension or optimize treatment. In the vast majority of cases, primary hypertension is managed in primary care.

In Quebec, access to a family doctor remains a real challenge for many people. Medical clinics that offer comprehensive health screenings are a practical option for people without a regular doctor who want to have their blood pressure and cardiovascular risk factors assessed.

Clinique Omicron and blood pressure monitoring

Our service points in Quebec offer health check including blood pressure measurement, assessment of cardiovascular risk factors, and, if necessary, additional tests. Whether you don’t have a family doctor or simply want more frequent checkups, you can book an appointment online. See our rates to know the available services.

Knowing your numbers, understanding what they mean, and knowing when to take action is the best starting point for taking control of your cardiovascular health.

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