Peak Growth Hormone Level Variability during Insulin Tolerance Test in Children with Short Stature

To determine the variations in peak growth hormone levels during insulin tolerance test (ITT) in diagnosis of growth hormone deficiency (GHD) in children presenting with short stature.

Descriptive study.

Department of Pediatric Endocrinology, National Institute of Child Health (NICH), from January to December 2018.

Clinical records of all children who underwent ITT during the above mentioned period were reviewed. All 348 children of either gender from 2-17 years of age with height more than 2SD below the mean (<3rd percentile) suspected GHD and subjected for ITT were included. Verbal consent was taken from all parents. Children below 2 years and with other causes of Short Stature like hypothyroid, celiac, cardiac, chronic liver, kidney diseases and syndrome were excluded.

Total 348 children were subjected to ITT. Out of these 48.3% were found to have GH levels <5ng/ml, 33.6% b/w 5-10 ng/ml and 18.1% >10 ng/ml. Precisely peak GH levels at different time intervals are 1.1%, 19.3%, 47.4%, 29.9%, and 2.3% for 0, 30, 60, 90 and 120 minutes respectively. Mostly peak growth hormone levels were accomplished at 60 minutes followed by 90 and then at 30 minutes. Hypoglycemia was achieved 0.8%, 47%, 26%, 24% and 1% at 0, 30, 60, 90, and 120 minutes.

The 0, 30, 60, and 90 minutes samples are adequate to confirm the diagnosis of GH deficiency. This shorter duration of ITT to 90 minutes is cost effective as it decreases the financial burden of unnecessary testing. Additionally, it reduces the risk of side effect like hypoglycemia. Key Words: Short stature, Growth hormone deficiency, Insulin tolerance test.