The arginine stimulation test: timing of peak is not a helpful parameter in the diagnosis of growth hormone deficiency.

Background: A typical peak timing in the glucagon stimulation test has been reported as an indication of growth hormone (GH) deficiency. Other stimulation tests have not been evaluated.

Objective: To evaluate the clinical usefulness of peak timing in the arginine stimulation test (AST) for growth hormone deficiency.

Methods: Retrospective review of 199 ASTs from one center. Outcomes included correlation of peak times with (a) frequency of deficient peak; (b) growth velocity standard deviation scores (GVSDSs); (c) other evidence of pituitary pathology; (d) results of confirmatory clonidine test; and (e) response to GH treatment.

Results: The peak in 83/109 (76.14%) sufficient tests occurred at typical times vs. 45/72 (62.5%) deficient tests (p<0.05). GVSDS on GH treatment was greater among patients with typical timing in the AST compared with atypical timing (2.67 ± 0.59 vs. 0.46 ± 1.17, p=0.021). No other variable correlated significantly with AST timing.

Conclusions: Timing of peak in the AST is not a clinically useful parameter.