Tests and diagnosis

By Mayo Clinic Staff

As part of regular well-child care, the doctor calculates your child's body mass index (BMI) and determines where it falls on the national BMI-for-age growth chart. The BMI helps indicate if your child is overweight for his or her age and height.

Using the growth chart, your doctor determines your child's percentile, meaning how your child compares with other children of the same sex and age. So, for example, you might be told that your child is in the 80th percentile. This means that compared with other children of the same sex and age, 80 percent have a lower BMI.

Cutoff points on these growth charts, established by the Centers for Disease Control and Prevention (CDC), help identify overweight and obese children:

  • BMI-for-age between 85th and 94th percentiles — overweight
  • BMI-for-age 95th percentile or above — obesity

Because BMI doesn't consider things like being muscular or having a larger than average body frame and because growth patterns vary greatly among children, your doctor also factors your child's growth and development into consideration. This helps determine whether your child's weight is a health concern.

In addition to BMI and charting weight on the growth charts, the doctor also evaluates:

  • Your family's history of obesity and weight-related health problems, such as diabetes
  • Your child's eating habits
  • Your child's activity level
  • Other health conditions your child may have

Blood tests

Your child's doctor may order blood tests if he or she finds that your child is obese. These tests include:

  • A cholesterol test
  • A blood sugar test (fasting blood glucose)
  • Other blood tests to check for hormone imbalances that could affect your child's weight

Some of these tests require that your child not eat or drink anything before the test. Your child's doctor should tell you whether your child needs to fast before a blood test and for how long.

Feb. 15, 2014