title: Arginine and clonidine stimulation tests for growth hormone deficiency revisited--do we really need so many samples?
abstract: Growth hormone (GH) reserve is defined biochemically by the peak serum concentration after stimulation with a known secretagogue. Arginine and clonidine stimulation tests are currently performed with 5 timed blood samples. We evaluated the diagnostic utility of taking fewer samples by retrospectively analyzing 289 tests (202 arginine and 87 clonidine) performed in a single hospital. 123/202 (60.9%) arginine tests and 46/87 (52.9%) clonidine tests had at least one sample above 10 ng/ml. These were defined as negative for GH deficiency and studied further. For arginine tests, three samples taken at 0', 45' and 90' would have provided an acceptable false positive rate of 4.5%. For clonidine tests, two samples taken at 60' and 90' provided a false positive rate of 4.3%. Addition of either a 0' or 120' sample further reduced the false positive rate to 2.2%. Both the arginine and clonidine stimulation tests can be reliably performed with fewer samples.
authors.affiliation: Department of Pediatrics, Ein Kerem Campus, Hadassah Hebrew University Medical Center, Jerusalem, Israel.
authors.forename: Lili
authors.initials: L
authors.lastname: Muster
authors.forename: David H
authors.initials: DH
authors.lastname: Zangen
authors.forename: Rafael
authors.initials: R
authors.lastname: Nesher
authors.forename: Harry J
authors.initials: HJ
authors.lastname: Hirsch
authors.forename: Zvi
authors.initials: Z
authors.lastname: Muster
authors.forename: David
authors.initials: D
authors.lastname: Gillis
mesh_terms: D000293:Adolescent; D001120:Arginine; D002648:Child; D002675:Child, Preschool; D003000:Clonidine; D003940:Diagnostic Techniques, Endocrine / Q000191:economics / Q000706:statistics & numerical data*; D005260:Female; D006130:Growth Disorders / Q000097:blood / Q000175:diagnosis*; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012189:Retrospective Studies; D018401:Sample Size; D012680:Sensitivity and Specificity
chemical_list: D001120:Arginine; D003000:Clonidine