High blood pressure is not exclusive to adult population. It can also occur in children and teenagers. The prevalence of high blood pressure among adolescents is increasing. This increase is probably due to alteration in lifestyle factors resulting in obesity, sedentary life, unhealthy diet etc. More aggressive screening for blood pressure might also contribute partially to this increased prevalence of high blood pressure in teens. High blood pressure in teens should be taken seriously, as the target-organ damage due to hypertension can start in this age group also. Also, slightly raised blood pressure (prehypertension) increases the future risk of having hypertension.
Diagnosing hypertension in teenagers requires multiple blood pressure measurement over 2 to 4 weeks periods. A single high blood pressure reading is not termed hypertension unless it is associated with symptoms or is extremely high reading.
Since the normal blood pressure varies with the age, gender and height in children and adolescents, the criteria for diagnosing hypertension in teenagers are somewhat different than that for adults.
As per the currently accepted criteria (The Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescent):
- “Hypertension is defined as average SBP and/or DBP that is greater than or equal to the 95th percentile for sex, age, and height on three or more occasions”
- “Prehypertension in children is defined as average SBP or DBP levels that are greater than or equal to the 90th percentile, but less than the 95th percentile”
- “As with adults, adolescents with BP levels greater than or equal to 120/80 mmHg should be considered prehypertensive”
What is Percentile?
For understanding percentile consider this example. Suppose there are 100 teenage boys of same age and height. Their blood pressure is measured and recorded. The 5 highest readings of blood pressure (top 5%) will be the blood pressure values above 95th percentile. Similarly, the 10 highest readings of the blood pressure will be the readings above 90th percentile. If this is done for 1000 boys, then the corresponding number would be top 50 and top 100. For defining normal values of blood pressure for a particular gender, age and height, the blood pressure of a large number of same age, gender and height persons are recorded and the blood pressure reading above which the top 5% and 10% of the values are found is recorded. This is used as the criteria for diagnosis blood pressure in that group (gender, age and height).
The various percentile values for blood pressure based on age, gender and height can be found here on the pages 10-13 of “The Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescent” published by U.S. Department of Health and Human Services.
Essential Hypertension and Secondary Hypertension
Even in teenagers, the majority of high blood pressure is essential hypertension (i.e. blood pressure with no obvious cause). However, a significant number of cases are due to some other primary disease condition. Hence, a thorough search for the cause of hypertension is warranted before terming the raised blood pressure as essential hypertension.
The most common causes of secondary hypertension in teenagers are Coarctation of Aorta, Pheochromocytoma, Renal Artery Stenosis, Chronic Renal Disease, and Side effects of medications. There are numerous other causes, which are quite rare. Secondary hypertension sometimes might be very difficult to control with standard anti-hypertensive drug regimens and lifestyle modifications (termed as resistant hypertension). Also, they might be curable if the underlying cause is treatable. This makes differentiating secondary hypertension and essential hypertension very important. The table given below describes these most common causes of secondary hypertension.
Table 1: Common Causes of Secondary Hypertension in Teenagers
Coarctation of Aorta
In this condition there is narrowing of a segment of aorta. Since renal artery originates distal to this narrowing, the pressure in this vessel is low, causing salt and water retention by the kidneys.
Epinephrine and Norepinephrine releasing tumor of the adrenal glands. The chemical raise blood pressure.
Renal Artery Stenosis
Narrowing of the artery that supplies blood to the kidneys. Kidney perceives low blood pressure and causes increased salt and water retention, thus raising the blood pressure.
Chronic Renal Disease
Kidney diseases can cause hypertension by retaining salt and water.
Various drugs like Corticosteroids, Anabolic Steroids, Oral Contraceptive Pills, etc. can cause high blood pressure.
Numerous other less common causes like Endocrine Disorder, Various other kidney diseases, Genetic Diseases, Tumors etc.
Approach to Treatment of High Blood Pressure in Teens
A blood pressure over 90th percentile for age, gender and height of a teenager requires therapeutic interventions. Teenagers are thoroughly evaluated for the presence of a primary cause for the raised blood pressure. If the raised blood pressure is a secondary hypertension, therapy is aimed at treating the primary condition (if possible). For e.g. if there is Pheochromocytoma, it can be surgically removed. This cures the hypertension in nearly 3/4th of the cases. Coarctation of aorta can be surgically corrected to treat hypertension. However, if such cure not possible, then anti-hypertensive drugs are used to treat secondary hypertension.
In cases of high blood pressure with no obvious cause, pharmacological therapy is not indicated in prehypertension unless there are other concurrent conditions like diabetes mellitus, heart failure, hypertrophy of the left side of heart, kidney disease or evidence of hypertensive damage to organs. Such cases are managed with lifestyle modifications like aerobic exercises, diet management, control of weight if overweight, and total abstinence from alcohol and smoking. Adopting a healthier lifestyle by these measures should be encouraged in all teenagers even if the blood pressure is in the normal range. High blood pressure qualifying as hypertension requires control of high blood pressure with anti-hypertensive drugs also in addition to the lifestyle changes mentioned above. Lifestyle changes are usually tried first, and anti-hypertensive drugs are started if they fail to lower the blood pressure in the desired range.
Prevention of Essential Hypertension in Teens
Adopting a healthier lifestyle is recommended for everyone irrespective of the current blood pressure. It reduces the risk of not only essential hypertension, but also some of the causes of secondary hypertension like renal artery stenosis. The most important lifestyle modifications are:
- Adopting a healthier diet (DASH-type dietary plan)
- Aerobic exercises and restricting sedentary activity
- Control of weight if overweight
- Reducing dietary salt intake
- No Smoking
- No Alcohol
- Taking adequate sleep