Hypertension is one of the most common non-communicable diseases affecting the world population at large and a large majority of Nigerians in particular. It is a serious condition and can cause other diseases in the body.  It is a leading cause of African morbidity and mortality with Nigeria contributing to the larger part of the disease burden.

According to the World Health Organization (WHO), “Hypertension is defined as a condition in which the blood vessels have abnormally high blood pressure that is persistent.”

The force with which the blood pushes against the walls of the vessels with every pumping action of the heart is known as blood pressure. This blood pressure has a normal value which should not be exceeded for optimal healthy living. Once this blood pressure is high over a consistent period of time, this can be said to be hypertension.

The blood pressure is measured by two values namely systolic and diastolic blood pressure. The systolic blood pressure is the force the blood exerts on the artery wall when the heart is actively beating, i.e., pumping blood. It is usually recorded as the first value. The diastolic blood pressure is the force the blood exerts on the artery wall when the heart is at rest i.e., in between beats. It is recorded as the second value.

In general, a blood pressure reading greater than 140/90mmhg is considered an elevated value and requires some form of clinical intervention.

Prevalence of Hypertension

Hypertension is globally prevalent and is a common cause of premature deaths all over the world. It is one of the known risk factors for cardiovascular diseases as well as diseases affecting other organs like the kidneys and so on. Over 1 in 4 men and about 1 in 5 women are said to have hypertension.

LMICS (Low and Middle-Income Countries) such as Nigeria have a higher prevalence of hypertension in general. This is accompanied by reduced awareness of the condition with poor treatment and control. The direct opposite is what is seen in developed countries.

In Sub-Saharan Africa, hypertension has become a public health challenge of note. Nigeria, being one of the most populous nations in the Sub-Saharan region of Africa, has a large share of the hypertension burden. Worldwide, it is one of the foremost risk factors for cardiovascular diseases but in Nigeria, hypertension is the most frequently diagnosed risk factor. Hypertension is said to account for at least 25% of emergency cases in tertiary hospitals. Several studies have been done to estimate the epidemiological impact of hypertension in Nigeria.

According to a study on “the prevalence, awareness, treatment, and control of hypertension in Nigeria” by Dr. Davies Adeloye, it was estimated that at least 1 in 4 adults in Nigeria suffer from hypertension. Another study found that the mean blood pressure in the Nigerian population is higher than that obtained in the United States and Europe. 

An estimated prevalence of 28.9% of the Nigerian population was derived based on a meta-analysis of published studies. Hypertension is defined as a value greater than 140/90 mmHg in this context.

Causes of Hypertension

The exact cause of hypertension is not known precisely and can be attributed to many factors. This is why research on its pathophysiology is ongoing.

Types of Hypertensions

Hypertension may be classified as:

• Essential or Primary Hypertension
• Secondary Hypertension

Essential Hypertension

Essential hypertension or primary hypertension occurs when the cause of the hypertension isn’t linked to any other disease process in the body. Instead, it could develop due to environmental as well as genetic factors. This makes up a vast majority of hypertension cases in the general population.

Environmental factors play a major role in the development of primary hypertension. However, multiple genetic patterns of inheritance have been shown to be an implicating factor in the etiology of primary hypertension. Some of these factors are:

• Age: Increased age predisposes to a higher likelihood of hypertension
• Diabetes Mellitus (DM): People who are diagnosed with DM may also have a higher tendency to develop hypertension.
• Excessive Salt Intake: Several studies have implicated this factor as a major risk factor for essential hypertension.
• Excessive Caffeine Intake: This has also been implicated to be a likely risk factor.
• Obesity: This is an excessive and abnormal accumulation of fat that is harmful to health. It is a known risk factor in the development of hypertension
• Sedentary Lifestyle: This has been implicated as a risk factor for several non-communicable diseases, the chief of which is hypertension.
• Family History: Considering a genetic standpoint, people with a family history of hypertension have a proven risk of having hypertension.
• Africans and African-Americans: These subtypes of people have been shown to have an increased tendency to develop hypertension, although other secondary factors are at play. Hypertension is a Blackman’s disease.

Secondary Hypertension

This can be described as hypertension due to a known, proven cause in the body. There are many such causes which can be categorized as:

• Kidney Diseases: Renal malfunction is one of the most common causes of secondary hypertension. Some of the renal conditions implicated are Chronic Kidney Disease, Urinary Tract Obstruction, Renal vasculitis, Coarctation of the aorta, and Polycystic Kidney disease amongst others.
• Endocrinal Causes: Hormone imbalances have also been shown to cause secondary hypertension. Some of these conditions include Cushing syndrome, primary aldosteronism, and others.
• Use of Oral Contraceptives: Studies have shown that women who use oral contraceptives have a higher likelihood of developing secondary hypertension. This likelihood is increased if she is above the age of 35 years, is obese, and has a family history of hypertension.
• Use of Drugs and Other Substances: Some drugs that have been implicated include corticosteroids, erythropoietin, decongestants that contain ephedrine, adrenergic drugs, and others. Substances include cocaine, nicotine, and alcohol amongst others.
• Neurogenic Causes: These factors originate primarily from the brain and they include certain types of brain tumors, autonomic dysfunction, intracranial hypertension, sleep apnea, and others.

Conclusion

A lot has been said about hypertension which is a Non-Communicable Disease of serious public health concern. A low level of awareness coupled with a long asymptomatic period may be responsible for the high burden of hypertension in Nigeria.