Background: Growth hormone deficiency (GHD) is a potential consequence of traumatic brain injury (TBI),\nincluding sport-related concussion (SRC). GH stimulation testing is required for definitive diagnosis; however, this is\nresource intensive and can be associated with adverse symptoms or risks. Measurement of serum IGF-1 is more\npractical and accessible, and pituitary tumour patients with hypopituitarism and low serum IGF-1 have been shown\nto have a high probability of GHD. We aimed to evaluate IGF-1 measurement for diagnosing GHD in our local TBI\npopulation.\nMethods: We conducted a retrospective chart review of patients evaluated for GHD at the TBI clinic and referred\nfor GH stimulation testing with insulin tolerance test (ITT) or glucagon stimulation test (GST) since December 2013.\nWe obtained demographics, TBI severity, IGF-1, data pertaining to pituitary function, and GH stimulation results.\nIGF-1 values were used to calculate z-scores per age and gender specific reference ranges. Receiver operator curve\nanalysis was performed to evaluate diagnostic threshold of IGF-1 z-score for determining GHD by GST or ITT.\nResults: Sixty four patient charts were reviewed. 48 patients had mild, six had moderate, eight had severe TBI, and\ntwo had non-traumatic brain injuries. 47 patients underwent ITT or GST. 27 were confirmed to have GHD (peak\nhGH < 5 �¼g/L). IGF-1 level was within the age and gender specific reference range for all patients with confirmed\nGHD following GH stimulation testing. Only one patient had a baseline IGF-1 level below the age and gender\nspecific reference range; this patient had a normal response to GH stimulation testing. ROC analysis showed IGF-1\nz-score AUC f, confirming lack of diagnostic utility.\nConclusion: Baseline IGF-1 is not a useful predictor of GHD in our local TBI population, and therefore has no value\nas a screening tool. TBI patients undergoing pituitary evaluation will require a dynamic test of GH reserve.
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