Diagnosis of growth hormone deficiency by using the arginine provocative test: is it possible to shorten testing time without altering validity?

Background: The arginine test is used for the diagnosis of growth hormone deficiency (GHD), but its duration is not uniform and varies from 180 to 90 min. Subjects and Methods: To standardize this test, evaluating the possibility to shorten it to 90 min, we investigated the response of GH to the arginine test in 208 children evaluated for short stature (height less than –2 SD); 67 were diagnosed with idiopathic short stature (ISS) and 141 with GHD. We calculated the frequency distribution of the GH peaks to arginine in GHD and in ISS at various times and the percentage of GH peaks to arginine before and after 90 min in all and in ISS children. Results: The GH peak distribution varied between 30 and 120 min, even though the vast majority of peaks occurred between 30 and 90 min. There was no significant difference (p 1 0.05) in the peak distribution between ISS and GHD children. The percentages of GH peaks within 90 min were 95.2% in all children and 100% in ISS. Conclusion: The arginine test can be administered for only 90 min without significantly changing its validity, in order to reduce the discomfort of patients and the cost of the test.