Growth hormone deficiency short stature in a third world adult endocrine clinic: usefulness of clonidine test in its diagnosis

Background: Short stature (SS) can be treatable; yet the diagnostic value of a simple test in correctly identifying the two common etiologies in developing countries, viz., growth hormone deficiency (GHD) and normal variant short stature (NVSS), has not been reported in a typical third world population. Objectives: The aim of the study was to evaluate the reliability of clonidine test in differentiating short stature caused by GHD from NVSS. Settings and Design: Data of subjects evaluated for growth hormone deficiency SS at a Saudi Arabian university hospital were retrospectively reviewed. Materials and Methods: Clonidine and insulin tolerance tests (ITT) were conducted on 60 subjects aged 12 years and above with SS, while peak stimulated growth hormone cut off value of < 10 μg/l was used to diagnose GHD. Statistical Analysis: Sensitivity and specificity for clonidine test and ITT were computed, while receiver operator characteristic (ROC) curves were constructed from the results in order to assess the diagnostic usefulness of the two tests. Mann-Whitney test was used to determine level of significance. Results: Clonidine test showed superior sensitivity and specificity, viz., 81% and 82%, as against 65% and 59% for ITT respectively. Overall, the efficiency of clonidine test in correctly differentiating short stature caused by GHD from NVSS was higher, viz., 90%, compared to ITT's 77%. Conclusions: Clonidine test proved to be an excellent test for initial assessment of GHD and may be used as a screening test for short stature in third world countries