Sfeir JG, et al. - Researchers investigated how to choose a laboratory method for diagnosing GH deficiency (GHD) when it happens as a late effect of radiotherapy in childhood cancer survivors (CCSs). The diagnostic accuracy of various dynamic tests for GHD in CCSs vs non-CCSs seemed to follow the same patterns. Given the primarily hypothalamic dysfunction in CCSs, interpreting GHRH stimulation is a challenge. In this population, IGF-1 and IGF-binding protein 3 (IGFBP-3) performed poorly.

Methods

• Medline, Embase, Cochrane Central Register of Controlled Trials and Database of Systematic Reviews, and Scopus were searched for studies evaluating GHD.
• Studies using IGF-1 or IGFBP-3 measurements compared with GH dynamic testing were identified.

Results

• Fifteen studies (IGF-1 [8 studies] and IGFBP-3 [7 studies]) enrolling 477 patients were included.
• Wide variation in comparator tests was noted.
• Although strongly correlated, both IGF-1 and IGFBP-3 had suboptimal diagnostic accuracy, and simultaneous use of both tests in the same cohort did not improve the diagnostic accuracy.
• For appropriately identifying patients with GHD, dynamic tests remained the most accurate despite high variability in the testing protocols.
• Outcomes suggest the insulin tolerance test (ITT) to be the most accepted reference test when used alone or in combination with arginine; however, among practice groups, there were no standardized testing strategies.
• GHRH and arginine stimulation were almost similar to ITT regarding their performance; however, one study displayed 66% sensitivity and 88% specificity for GHRH with arginine stimulation compared with the ITT.
• They identified no sufficient data assessing the accuracy of serial GH testing (nocturnal or over 24 hours).