What laboratory tests should be ordered for a 17-year-old patient with obesity?

Laboratory Tests for Obesity in a 17-Year-Old

For a 17-year-old patient with obesity, laboratory testing should include a comprehensive metabolic panel, fasting lipid profile, hemoglobin A1c, fasting glucose, thyroid function tests, and liver function tests as the core screening panel. 1

Core Laboratory Tests

Metabolic Screening

• Fasting glucose and hemoglobin A1c: To screen for prediabetes and diabetes 1
• Fasting lipid panel: Including total cholesterol, LDL-C, HDL-C, and triglycerides to assess cardiovascular risk 1
• Comprehensive metabolic panel: To evaluate electrolytes, renal function, and baseline metabolic status 1
• Liver function tests (AST, ALT): To screen for non-alcoholic fatty liver disease 1
• Thyroid function tests (TSH, free T4): To rule out hypothyroidism as a contributor to weight gain 1

Additional Tests Based on Clinical Findings

If the physical examination or history suggests specific concerns, consider:

• Fasting insulin level: To evaluate for insulin resistance, especially with acanthosis nigricans 1, 2
• Uric acid: Associated with metabolic syndrome 1
• Vitamin D level: Often deficient in adolescents with obesity 1
• High-sensitivity CRP: To assess for inflammation associated with obesity 1

Screening for Comorbidities

For females:

• Consider reproductive hormone panel (FSH, LH, estradiol, testosterone) if menstrual irregularities are present to evaluate for polycystic ovary syndrome 1

For all patients with severe obesity or specific symptoms:

• Sleep study screening questionnaire (consider polysomnography if positive screening) for obstructive sleep apnea 1
• Urinary albumin-to-creatinine ratio: To screen for early kidney damage, especially if hypertension or abnormal glucose metabolism is present 1

Clinical Context for Laboratory Testing

Laboratory testing should be guided by a thorough clinical assessment including:

• BMI calculation and percentile (obesity defined as ≥95th percentile for age and sex) 1
• Waist circumference measurement (central adiposity assessment) 1
• Blood pressure measurement with appropriate-sized cuff 1
• Physical examination findings such as acanthosis nigricans (insulin resistance), hirsutism (PCOS), or hepatomegaly (fatty liver) 1

Important Considerations

• Laboratory results should be interpreted in the context of the adolescent's pubertal stage and sex 1
• Abnormal laboratory findings warrant appropriate follow-up and may necessitate referral to specialists 1
• Screening should be repeated annually in adolescents with persistent obesity 1
• Consider family history of obesity-related conditions when interpreting results 1

Common Pitfalls to Avoid

• Don't overlook mental health screening: Depression and eating disorders are common comorbidities that require evaluation beyond laboratory testing 1
• Don't attribute all abnormal findings to obesity: Consider other potential causes of laboratory abnormalities
• Don't delay treatment while waiting for laboratory results: Lifestyle interventions should begin immediately 1
• Don't forget to screen for medications that may contribute to weight gain 1
• Don't miss the opportunity for early intervention: Identifying metabolic abnormalities in adolescents provides an opportunity for early treatment to prevent progression to chronic disease 1, 2