DR MAXWELL ADEYEMI

HYPERTENSION IS common in many people, especially in people of African descent, wherever they reside. Despite the availability of a wide variety of antihypertensive drugs, poorly controlled hypertension is the single largest risk factor for organ damage. This is not just a consequence of socio-economic deprivation, because even in countries that subsidise medications, hypertension control rates remain poor.

What is blood pressure

Blood pressure (BP) is the pressure of the blood against the walls of the arteries when the heart pumps blood into the arteries. Normal blood pressure is below 120/80 mmHg. The top number (systolic) is the pressure when the heart contracts to pump blood into the arteries, and the bottom number (diastolic) is the pressure when the heart relaxes between beats. Both numbers are equally important. When blood pressure is high and untreated, it can damage blood vessels in various organs in the body.

What are the types

of hypertension

There are two types of hypertension. Primary hypertension - also known as essential hypertension - refers to hypertension that has no known cause. Over 90 per cent of people who have hypertension have primary hypertension.

Secondary hypertension is when there is an identifiable and potentially reversible cause of hypertension. Less than ten per cent of hypertension is the secondary type and it is more prevalent in younger people. Some of the causes of secondary hypertension include high levels of hormones that control blood pressure, narrowing of arteries that supply blood to the kidneys, side effects of medications like birth control pills and diet pills.

Why is hypertension common

in people of African descent?

Researchers don't have a definitive explanation, but it may be due to genetic factors. It has been theoried that people of African descent possess a gene - a thrifty gene for sodium - that enabled their kidneys to excessively reabsorb and conserve sodium in the hot, dry climate of Africa to avoid dehydration.

However, as people migrated out of Africa to cooler climates, they carried this gene with them, resulting in sodium avidity that leads to hypertension, especially in societies where salt is abundant in foods.

Also, research shows that there may be a gene that makes people of African descent more salt sensitive. In people who have this gene, as little as half a teaspoon of salt could raise blood pressure by 5 mmHg. Furthermore, even among people of African descent with normal blood pressure, when given an equivalent amount of salt, their blood pressure rises higher, and their body retains more of the administered salt compared to white people.

Harmful effects

of hypertension

Hypertension usually has no symptoms. Organ damage goes on quietly without the individual having any symptoms (silent killer), until a catastrophic event occurs. Hypertension may cause heart failure, stroke, heart attack, kidney failure, abnormal heart rhythm, eye disease, erectile dysfunction and de