To determine whether the ITT, arginine (AST) and glucagon stimulation tests (GST) identify patients who have similar features of GH deficiency using a diagnostic threshold of 3 μg/l.
Patients and Methods:
5453 tests were available from 4,867 patients registered in the KIMS database (49.9% females, ITT = 3111, AST = 1390, GST = 952). Comparisons were made for GH peak, BMI, lipids, waist circumference, waist:hip ratio and quality of life (QoL-AGHDA questionnaire).
There were significant (p<0.0001) intra-individual correlations between the GH peaks for the ITT vs AST (r = 0.655), ITT vs GST (r = 0.445) and AST vs GST (r = 0.632). GH peaks in response to all tests were negatively correlated to the number of additional pituitary hormone deficiencies, and positively correlated to IGF-I SDS. BMI had a negative influence on all three tests.
Comparing GHD patients according to the diagnostic test used, most clinical variables did not differ between the groups. The only exceptions showing any difference were BMI being slightly higher in the AST and GST groups, triglyceride levels increased in the GST group, and IGF-I SDS was lower in the ITT and AST than in the GST group. Waist circumference was larger and quality of life was worse in the GST group than in the other groups.
This study demonstrates that the ITT, AST and GST produce similar GH peaks, are influenced by similar clinical factors and identify patients with similar features of GH deficiency at a diagnostic threshold of 3 μg/L.
2011. 1-26 p.