Interruption of GH Therapy on the Basis of GH Retesting at Puberty in Previously Diagnosed GHD Patients: Final Height Results

We compared clinical characteristics and final height (FH) data after replacement therapy of 2 groups of pts diagnosed as GHD before puberty and treated either until FH (group 1, persistent deficiency) or until puberty (group 2, transient deficiency) on the basis of GH retesting results. Inclusion criteria of the patients were: diagnosis of isolated and idiopathic GHD before puberty (2 pharm. tests with GH peak<8 ng/ml) and treatment with GH (7 mg/m2/wk) for at least 2 yrs before GH retesting. Retesting was performed in males at test. vol. 6-12 ml and in females at breast 2-3. Group 1 consisted of 38 pts (16 m, age 9.9±2.3; 22 f, age 9.7±1.7), while group 2 of 22 pts (13 m, age 9.9±1.9; 9 f , 9.2±1.4). Mean duration of therapy were 5.5 and 3.7 yrs in the 2 groups. Results: The differences found never reached statistical significance. Pts of group 1 vs group 2 showed a FH gain since diagnosis (FH-initial ht) sds of 0.86±0.7 vs 0.92±0.7 and a FH gain vs target ht (FH-TH) sds of –0.07±0.8 vs –0.45±0.8 sds. IGF-1 levels at retesting were 333±170 ng/ml in group 1 and 342±143 ng/ml in group 2. The table shows the results in pts subdivided into males and females. In the whole group FH was correlated with birth weight (p=0.02), initial ht (p=0.002), ht at start of puberty (p=0.007) and TH (p=0.01). FH-ht at retesting was correlated with TH (p=0.01) and birth weight (p=0.002). Therapy duration was unrelated to FH parameters. Conclusions: Patients with isolated idiopathic GHD showing a normal secretion at puberty and subsequently left untreated reached similar final height results to the pts with permanent GHD treated till FH, with no significant differences between males and females. In this type of pts, GH therapy at a dose of 7 mg/m2/wk seems to have little influence on final height results that were more dependent on the genetic characteristics of the subject.