Responses to GHRH plus arginine test are more concordant with IGF-I circulating levels than responses to arginine and clonidine provocative tests.
ABSTRACT Although pharmacological GH stimulation tests are still considered the gold standard for GH deficiency (GHD) diagnosis, they are burdened by poor specificity. The majority of children diagnosed as having GHD show normal GH responses when re-tested at the end of growth, thus questioning the initial diagnosis. We evaluated the concordance between IGF-I levels and GH responses to provocative tests.
We analyzed 105 GHRH plus arginine tests, 79 arginine tests, and 124 clonidine tests performed in 192 short children. IGF-I levels ≤-2SD score (SDS) were considered suggestive for high likelihood of GHD. The percentage of positive and negative results for each test was determined and compared with IGF-I levels, clinical follow-up and response to therapy.
In children with IGF-I>-2SDS the arginine test showed a concordance rate of 6.9%, the clonidine test of 28.6%, and GHRH plus arginine test of 70%. In children with IGF-I≤-2SDS the concordance was 96.1%, 85.7%, and 46.4%, respectively. The overall concordance was 66.7% for GHRH plus arginine, 42.7% for clonidine, and 27.8% for arginine tests.
Our results suggest that GHRH plus arginine test provides the best concordance with the assessment of IGF-I levels thus suggesting that the combination of the two procedures may significantly reduce the need of a second provocative test.
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ABSTRACT: In children with childhood-onset growth hormone deficiency, replacement GH therapy is effective in normalizing height during childhood and achieving adult height within the genetic target range. GH has further beneficial effects on body composition and metabolism through adult life. The transition phase, defined as the period from mid to late teens until 6-7 years after the achievement of final height, represents a crucial time for reassessing children's GH secretion and deciding whether GH therapy should be continued throughout life. Evidence-based guidelines for diagnosis and treatment of growth hormone deficient children during transition are lacking. The aim of this review is to critically review the up-to-date evidence on the best management of transition patients in order to ensure the correct definitive diagnosis and establish the appropriate therapeutic regimen.Frontiers in Endocrinology 01/2013; 4:34.