Evaluation of Permanent Growth Hormone Deficiency (GHD) in Young Adults with Childhood Onset GHD: A multicenter study

BACKGROUND Reconfirming the diagnosis of childhood onset growth hormone deficiency (GHD) in young adults is necessary to demonstrate the need for continuation of GH therapy. OBJECTIVE This nationally-based study was planned to establish GH status during adulthood in childhood-onset GH deficient patients and to evaluate factors that would predict persistency of the GHD. METHODS In this multicenter study, 70 GH deficient patients who had reached final height were evaluated after completion of GH treatment. Fifty-two patients (74%) had isolated GHD and 18 patients (26%) had multiple pituitary hormone deficiency (MPHD). Patients who had reached final height and the pubertal Tanner stage 5 were reevaluated for GH status. After at least 6 weeks of cessation of GH treatment, patients were retested with insulin induced hypoglycemia. RESULTS GHD was found to be transient in 64.3% of all patients. Of the isolated GH deficient patients 82.7% had transient GHD, whereas 88.9% of the MPHD patients showed persistent GHD. Comparison of isolated GH deficient and multiple hormone deficient patients indicated higher peak GH, IGF-I and IGFBP-3 levels in isolated GH deficient patients. No parameter was significantly different in the transiently and persistently GH deficient patients with respect to gender. Although specificity of IGF-I value of less than -2 SD showing persistency of GHD was lower than the specificity of IGFBP-3 value of less than -2 SD (65.7% vs 84%), negative predictive values were similar for the two parameters (85.2% and 84%, respectively). CONCLUSION Most of the cases of childhood onset GHD are idiopathic and the GHD is transient. In patients with MPHD, GHD is generally permanent. Low IGF-I and IGFBP-3 levels are supporting findings to show persistency of the GHD.