The textbook "Current Diagnosis and Treatment: Pediatrics" indicates that blood pressure measurements should be done on a yearly basis starting at the age of 3. Blood pressure measurements consist of two numbers that are measured in millimeters of mercury, abbreviated mmHg. The first number in a reading is called the systolic blood pressure; the second is the diastolic blood pressure. Depending on the child's age, sex and height, these numbers will fall within a certain range. Some are considered normal while others are too high to be considered healthy and may require further tests and even treatment.
Normal Blood Pressure
According to the National Heart Lung and Blood Institute, there is no single number the means a child has normal blood pressure. Instead, the numbers that are considered normal depend on three factors: a child's height, his gender and his age. Each of these factors affects whether a blood pressure reading will be called normal and healthy, or whether the blood pressure will be concerning or even be given the diagnosis of hypertension--high blood pressure. For instance, for a 10-year-old girl who is about 55 inches tall, a systolic blood pressure of less than 114 mmHg would be considered healthy and normal. For a 10-year-old boy of about the same height, the number is very similar: 115 mmHg for a systolic blood pressure reading is normal.
As children get older and taller, the small differences virtually disappear and normal readings start to be the same as what would be expected for adults: a 16-year-old girl who is just under 5-feet tall should have a systolic blood pressure of less than 120 mmHg; the blood pressure of a 16-year-old boy who is nearly 6-feet tall should also be less than 120 mmHg to be considered normal. In a child with normal blood pressure, the recommendation by the NHLBI is to recheck the blood pressure in one year.
Prehypertension
Prehypertension is a "gray zone" of blood pressure values. They are not quite high enough to be considered an official diagnosis of hypertension, but they are certainly higher than normal values. In medical terms, a child can be considered to have prehypertension if two readings within the same office visit are greater than 120/80 mmHg, but less than the 95 percent percentile for age, sex and height. Alternatively, if a child's systolic or diastolic blood pressure is more than the 90th percentile for his age, height, and sex, but less than the 95th percentile, this is also called prehypertension. What this means is that if the child's blood pressure reading is higher than that of 90 to 95 percent of children his age and height, the child is considered to have prehypertension. A diagnosis of prehypertension, as indicated by the NHLBI, warrants a re-check in six months' time, as well as counseling the child and his family about weight management if overweight is an issue.
Stage 1 Hypertension
The diagnosis of stage 1 hypertension is given if the child's systolic and/or diastolic blood pressure is greater than the 95th percentile for age, sex, and height, but less than, or equal to, the 99th percentile plus 5 mmHg. So if the child's systolic blood pressure falls between the value given for the 95th percentile and the number obtained when adding 5 to the 99th percentile value, the child has stage 1 hypertension.
An example of a child with stage 1 hypertension is a 12-year-old girl, who is just under 5-feet tall, with a systolic blood pressure reading of 121 to 133 mmHg. This number is large enough that she would be given the diagnosis of stage 1 hypertension. In such cases, the recommendation by the National Heart Lung and Blood Institute is that the blood pressure be rechecked quickly, within one to two weeks. If the value on rechecking is still this high, further evaluation needs to be done, and the child may need to begin treatment for her high blood pressure. As in the case of prehypertension, weight management techniques may need to be discussed if the child is overweight or obese.
Stage 2 Hypertension
Stage 2 hypertension is the most serious hypertension diagnosis--the numbers are the highest and thus most concerning. A child is said to have stage 2 hypertension if his systolic and/or diastolic blood pressure is greater than the number obtained when adding 5 mmHg to the 99th percentile value for blood pressure. Any reading of systolic blood pressure higher than 133 mmHg would give her a diagnosis of stage 2 hypertension. In a case like this, further tests and evaluation, as well as treatment, are begun quickly: if the child has no symptoms, the recommendation is to start within the week. If the child shows symptoms of the alarmingly high blood pressure such as headaches or nausea and vomiting, however, evaluation and treatment are begun immediately.
References
- "Current Diagnosis and Treatment in Family Medicine"; Jeannette E. South-Paul, Samuel C. Matheny, and Evelyn L. Lewis; 2008
- "Current Diagnosis and Treatment: Pediatrics;" William W. Hay, Jr., Myron J. Levin, Judith M. Sondheimer, and Robin R. Deterding; 2009
- NHLBI: Pocket Guide to Blood Pressure Measurement in Children
