Tests and diagnosis
The test for high blood pressure is painless. Blood pressure is measured with an inflatable arm cuff and a pressure-measuring gauge.
The cuff size used will vary with your child's arm circumference and any growth that has occurred. Your child may feel a tight squeeze around the arm when the cuff is inflated. You can find out what your child's blood pressure is immediately after the test is over.
A blood pressure reading has two numbers. The first, or upper, number measures the pressure in your child's arteries when his or her heart beats (systolic pressure). The second, or lower, number measures the pressure in your child's arteries between beats (diastolic pressure).
Normal blood pressure readings in children vary based on sex, age and height, so what may be a high blood pressure reading for a 4-year-old boy may be normal for a 10-year-old girl. Your child's doctor will let you know if your child's blood pressure readings are elevated.
Your child won't be diagnosed with high blood pressure after only one blood pressure measurement. To diagnose high blood pressure, it takes three measurements that show your child's blood pressure is higher than normal over the course of at least three visits to the doctor. During a single visit, your child’s blood pressure may be measured several times for accuracy.
If your child's blood pressure is higher than normal, it should be checked about every six months after high blood pressure is first diagnosed.
If your child is diagnosed with prehypertension or hypertension, your child's doctor may also perform these tests to see if another condition is causing your child's high blood pressure:
- Blood test to check your child's blood sugar, kidney function and blood cell counts
- Urine sample test (urinalysis)
- Echocardiogram, a test to check the blood flow through your child's heart, if your child's doctor suspects a structural heart problem may be causing high blood pressure
- Ultrasound of your child's kidneys
If your child's doctor is having difficulty diagnosing high blood pressure, or wants to monitor your child's treatment, he or she may recommend ambulatory monitoring. In ambulatory monitoring, your child wears a device that measures his or her blood pressure throughout the day.
This is not yet common practice, and more research is necessary to see if ambulatory monitoring helps in the treatment and diagnosis of high blood pressure in children. However, ambulatory monitoring may be especially helpful if your child is normally quite nervous at the doctor's office, because he or she may have what's known as white-coat hypertension — blood pressure that's only temporarily elevated due to anxiety from being at the doctor's office.