Diagnostic Utility of the ratio of Serum Insulin like Growth Factor-1 to its Serum Binding Protein-3 in Growth Hormone Deficiency in comparison to Clonidine Stimulation Test

**Title: “**Diagnostic utility of the ratio of Serum Insulin like Growth Factor-1 (IGF-1) to its Serum  Binding Protein-3 (IGFBP-3)  in Growth Hormone Deficiency in comparison to Clonidine Stimulation Test”

Growth hormone deficiency (GHD) is an important treatable cause of short stature (SS) in children. Its diagnosis however proves to be rather difficult because of a true gold standard diagnostic test. Classically hormonal evaluation for GHD is established by Growth Hormone Stimulation Test. However GH stimulation tests do not demonstrate perfect sensitivity or specificity allowing for potential false-negative or false-positive results. Other drawbacks of GH stimulation tests namely time-consuming invasive nonphysiological nonreproducible and potentially hazardous nature. It has motivated investigators to search for more promising diagnostic tools. Insulin like Growth Factor (IGF-1) concentration is most widely used for the diagnosis of GHD. However more than half the therapeutic response is accounted for by variability in the serum concentrations of IGF-1 and Insulin like Growth Factor Binding Protein (IGFBP-3). So IGF-1 and  IGFBP-3 molar  ratio is used as  biochemical marker to diagnose growth hormone deficiency. Very few studies have investigated the utility of serum IGF-1 to IGFBP-3 ratio in the diagnosis of GHD. This study aims to investigate the performance of the IGF-1, IGFBP-3  independently and in combination with serum IGF-1 and IGFBP-3  ratio and to compare GH stimulation test in the diagnosis of GHD in children with Short Stature.