Endocrine Assessment of Pediatric Obesity

Currently 1 out of every 5 children (18.5%) meets the body mass index criteria for obesity (BMI ≥ 95th percentile). Among adolescents 9.5% are affected by severe obesity, in which their BMI is at the 120% of the 95th percentile or higher.

Diagnosing and classifying obesity

For children 2 years of age and older, obesity is diagnosed by a body mass index of the 95th percentile or higher using the 2000 CDC BMI charts based on age and sex. Extrapolated growth charts are available that allow assessment of obesity at higher percentiles. As a result, additional classifications of obesity are more recently being used as described below:

*Child’s BMI in kg/m² divided by BMI in kg/m² at 95th percentile for age-sex multiplied by 100

For children less than 2 years of age, weight-for-length rather than BMI is used for classifying overweight and obesity. While skinfold thickness and waist circumference are frequently used in the obesity research setting, currently the American Academy of Pediatrics (AAP) does not recommend use of these in routine practice due to sparse reference data for U.S. children, measurement errors, and lack of specific guidelines as basis for intervention.

Importance of growth charts

Growth charts are vital tool in the evaluation of obesity, not only for BMI classification, but to determine the age of onset of obesity. Having multiple measurements over time assists with determining the rate of weight gain, as well as linear growth velocity. Recognizing whether there is growth failure in height is critical for the evaluation of obesity.

Assessing for etiology

Key questions to ask when determining an etiology of obesity include:

• When did the weight gain start?
• Were there any other changes in health at the time of weight gain onset?
• Has the child been growing normally in height while gaining weight?

The timing and context of weight gain, age of onset, and presence or absence of normal linear growth can provide guidance in the next steps of evaluation.

Several specific etiologies of obesity are detailed below:

Most children will not have a clearly identifiable etiology of their obesity. In these cases, they are diagnosed with “common obesity.”

Identifying comorbidities

History and physical examination

History and physical examination should be performed to assess for etiologies of and potential comorbidities related to obesity, which can impact nearly every body system. While not a comprehensive list, below are some considerations for screening of obese children presenting for routine care.

Laboratory evaluation

There is significant practice variability among laboratory evaluation for obesity comorbidities across the country, likely due to lack of guidelines consensus.

Children’s Mercy generally recommends that hemoglobin A1c, AST/ALT, serum glucose and lipid profile (preferably fasting) be assessed every 1-2 years for obese children in the primary care setting. Lab assessments in obese children can be performed as early as 2 years of age, though most guidelines agree they be performed by age 10. Additional considerations for commonly performed laboratory assessments in obese children are discussed below.

• Hemoglobin A1c: In clinical practice, most experts agree a HbA1c of 6.0% or higher in children requires additional evaluation.
• Oral glucose tolerance testing (OGTT): OGTT is a useful assessment of impaired glucose tolerance/type 2 diabetes in children, but because of its invasiveness and cost we recommend it be performed in the primary care setting only for children who lack clearly abnormal hemoglobin A1c and fasting glucose, and who are at high risk of type 2 diabetes (e.g., family history, race, age, acanthosis).
• Insulin levels: Fasting insulin levels are NOT recommended for routine use in obesity screening.
• Thyroid studies: Thyroid function testing should be performed in any obese child with growth failure. However, routine screening of thyroid function in obese children who have no signs or symptoms of thyroid dysfunction other than weight gain should be avoided. If mild TSH elevation is found, but free T4 is normal, repeat assessment in 6-8 weeks is useful.
• Vitamin D assessment: If vitamin D assessment is performed in obese children, it should be done using a 25-hydroxyvitamin D level.

When should patients be referred for endocrine evaluation of obesity?

• Growth failure: Any child with rapid weight gain or obesity that demonstrates growth failure (crossing height percentiles curves downward) should be referred for evaluation of potential endocrinopathy.
• Abnormal puberty: Any child with obesity and abnormal puberty should be referred for endocrinology evaluation.
• Early onset obesity: Any child less than 5 years old, particularly if there are developmental delays or severe hyperphagia, should be referred to an endocrinologist (or geneticist).
• Abnormal comorbidity screening: Children with the following lab abnormalities should be referred for pediatric endocrinology evaluation:
  • Fasting glucose 100 mg/dL or higher
  • HbA1c of 6.0% or higher
  • 120 minute glucose following OGTT of 140 mg/dL or higher
  • For those children with an HbA1c 8.5% or higher, or serum blood sugar of 250 mg/dL or higher the on-call Endocrinology physician should be contacted for possible urgent insulin initiation.

If HbA1c and glucose are normal, but there are other comorbidity abnormalities (AST/ALT, lipids), intervention and referral to appropriate subspecialist depends on the severity of the abnormality.

Because modification of environmental factors (diet, activity, etc.) is the cornerstone of management for nearly all cases of childhood obesity, any patient with abnormal obesity comorbidity screening should also be directed to a registered dietitian, or if feasible, a comprehensive weight management program.

Referral instructions

Refer concerns regarding pediatric obesity to pediatric endocrinology for further evaluation.

At Children’s Mercy, patients have access to an established, experienced team of more than 20 pediatric endocrinologists and nearly 100 staff members who specialize in endocrine disorders. Obesity and obesity-comorbidity clinical resources in the division include:

• Type 2 Diabetes Prevention Clinic
• Polycystic Ovarian Syndrome Clinic
• Diabetes Center

Children’s Mercy also offers a comprehensive weight management program including:

• Weight Management Clinic
• Special Needs Weight Management Clinic
• Metabolic/Bariatric Surgery Program

Consultative services are also available with the hospital’s other service lines including the Ward Family Heart Center’s Preventive Cardiology Clinic; the Division of Nephrology’s Hypertension Clinic; the Division of Gastroenterology’s Liver Care Center; and the Department of Nutrition’s Outpatient Nutrition Clinic.

Select “Endocrine” from the list of specialties and “Overweight (abnormal weight gain)” under “Reasons for Consultation.”

All new referral requests are processed within 48 hours. Two phone attempts to contact the family and a final notification to the family to schedule will be made.

For assistance, call the Contact Center at (816) 234-3700 or toll-free at (800) 800-7300. The Contact Center can provide additional information regarding any supporting documentation needed for the referral.

For urgent requests to speak to a specialist, please call and ask to speak with the on-call pediatric subspecialist at 1 (800) GO-MERCY / (800) 466-3729.

These instructions are provided for informational purposes only. The choice of provider referral is at your discretion.

Additional resources

1. Skinner AC, Ravanbakht SN, Skelton JA, Perrin EM, Armstrong SC. Prevalence of Obesity and Severe Obesity in U.S. Children, 1999–2016. Pediatrics. 2018;141(3):e20173459. (2018). Pediatrics, 142(3). doi:10.1542/peds.2018-1916.
2. Barlow, S. E. (2007). Expert Committee Recommendations Regarding the Prevention, Assessment, and Treatment of Child and Adolescent Overweight and Obesity: Summary Report. Pediatrics, 120(Supplement 4). doi:10.1542/peds.2007-2329c.
3. Pediatric Obesity—Assessment, Treatment, and Prevention: An Endocrine Society Clinical Practice Guideline. (2017). The Journal of Clinical Endocrinology & Metabolism. doi:10.1210/jc.2016-2573.
4. Estrada, E., Eneli, I., Hampl, S., Mietus-Snyder, M., Mirza, N., Rhodes,E., . . . Pont, S. J. (2014). Children’s Hospital Association Consensus Statements for Comorbidities of Childhood Obesity. Childhood Obesity,
   10(4), 304-317. doi:10.1089/chi.2013.0120.