Evaluating Growth Hormone Levels in Adolescents

Initial Assessment and Biochemical Testing

The American Academy of Pediatrics recommends assessing growth parameters and pubertal development by plotting current height, height velocity over the past 6-12 months, and calculating mid-parental target height to determine if growth concerns are present 1
Documenting Tanner stage is essential for contextualizing GH dynamics and interpreting biochemical results, as recommended by the Endocrine Society 2, 3, 4
Obtaining a left wrist radiograph to assess bone age and determine remaining growth potential is suggested by the Pediatric Endocrine Society 2, 3, 1
Measuring serum IGF-1 level and comparing to local Tanner stage-matched, sex-matched, and age-matched reference ranges is recommended by the Endocrine Society 2, 3, 4, 1
Measuring thyroid function (TSH and free T3 or free T4) to exclude hypothyroidism is recommended by the American Thyroid Association 2, 3, 1

The Endocrine Society recommends cautious interpretation of marginal or mild IGF-1 elevation during mid-puberty (Tanner stage 2-3), as this is the peak growth spurt period 4
IGF-1 may be falsely low with concurrent severe hypothyroidism, malnutrition, or severe infection, as noted by the Pediatric Endocrine Society 4, 1, 5
IGF-1 may be falsely elevated with poorly controlled diabetes mellitus, hepatic/renal failure, or in girls taking oral estrogens, as reported by the Endocrine Society 4, 1, 5

The Pediatric Endocrine Society states that standard GH suppression testing (oral glucose tolerance test) is unreliable in adolescents, with approximately 30% of normally growing tall adolescents failing to suppress GH below 1 μg/L after glucose load despite being completely normal 4, 1, 5
GH suppression is sex and pubertal stage-specific in adolescents, with highest levels in mid-puberty (Tanner stage 2-3), particularly in girls, as noted by the Endocrine Society 4, 5

The American Academy of Pediatrics recommends following a sequence of measurements, including height, Tanner stage, mid-parental target height, serum IGF-1, thyroid function tests, and left wrist radiograph for bone age, to assess growth hormone levels in adolescents 1, 2, 3

The National Kidney Foundation recommends assessing serum creatinine, electrolytes, bicarbonate, calcium, phosphorus, alkaline phosphatase, albumin, fasting glucose, and hemoglobin A1c to exclude other causes of growth disturbance 2, 3
The Endocrine Society suggests assessing parathyroid hormone and 25-OH vitamin D if chronic kidney disease or metabolic bone disease is suspected 2, 3