Suppression of growth hormone by oral glucose in the evaluation of tall stature

Excess secretion of growth hormone is a rare diagnosis in children or adolescents with tall stature. An oral glucose tolerance test (OGT) with determination of growth hormone is generally recommended to exclude this disorder. In order to test the validity of this approach in pediatric subjects, OGT tests were performed in 126 tall subjects (age: 12.4 +/- 1.8 years; height: 3.1 +/- 0.8 SDS). Nonsuppression was present in 39 subjects, however, anthropometric analysis and follow-up excluded the diagnosis of eosinophilic pituitary adenoma in all patients. The lowest GH concentration was reached 90 min after ingestion of oral glucose, GH rose above baseline at 180 min. Plasma concentrations of glucose and insulin did not differ between suppressors and nonsuppressors. In conclusion, absent suppression of growth hormone by oral glucose is common in tall children and adolescents. The test is therefore not recommended as a general screening for excess growth hormone. Prolonging the test beyond 120 min does not increase the diagnostic value.