Despite guidelines recommending screening for hypopituitarism in patients with traumatic brain injury, researchers found a low prevalence of growth hormone deficiency in this patient population.
Risk for bias in pituitary testing also was high, according to data published in the Journal of Clinical Endocrinology & Metabolism.
The researchers included 439 Danish adults who received a head trauma diagnosis and 124 healthy control patients in their population-based cohort study. All patients underwent assessment of GH secretion at a median of 2.5 years after traumatic brain injury. They measured prevalence of GH deficiency using local vs. guideline cutoffs; insulin tolerance testing, pyridostigmine/GH-releasing hormone (GHRH) or GHRH-arginine testing; and assays with different isoform specificity.
Results revealed a lower prevalence of GH deficiency, as measured by local vs. guideline cutoffs using pyridostigmine/GHRH or GHRH-arginine testing (12% vs. 19%; P<.001), as well as by insulin tolerance test (4.5% vs. 5%; P=.09). Similarly, prevalence was lower as measured by insulin tolerance test vs. pyridostigmine/GHRH or GHRH-arginine testing when using both local cutoffs (P=.006) and guideline cutoffs (P<.001). Further, only 1% of patients exhibited GH deficiency on two tests.
The assay used did not significantly alter diagnostic outcomes.
“The study confirmed a high risk of bias in the management of pituitary testing of patients with [traumatic brain injury], and stresses the importance of a proper control group and stringent GH-testing including confirmatory testing, in cohorts with low a-priori likelihood of [GH deficiency] such as in [traumatic brain injury]. Our results question the evidence for newly introduced recommendations for routine pituitary assessment in [traumatic brain injury],” the researchers wrote.
Disclosure: The study received an unrestricted grant from Novo Nordisk, and Immunodiagnostic Systems provided free iSYS GH kits, but had no influence on results or their interpretation. The researchers report no relevant financial disclosures.