Prevalence of posttraumatic growth hormone deficiency is highly dependent on the diagnostic set-up: results from The Danish National Study on Posttraumatic Hypopituitarism.
BACKGROUND
Recent international guidelines suggest pituitary screening in patients with moderate and severe traumatic brain injury (TBI). Predominantly isolated GH deficiency (GHD) was reported in the literature, raising the question of potential methodological bias.


OBJECTIVE
Our objective was to assess the prevalence of GHD in patients admitted in 2008 with TBI, with concurrent assessment of methodological bias.


METHODS
We conducted a nationwide population-based cohort study at tertiary referral university hospitals.


METHODS
Participants were Danish patients with a head trauma diagnosis from the Danish Board of Health diagnostic code registry; 439 patients and 124 healthy controls underwent dynamic assessment of GH secretion 2.5 years (median) after TBI.


RESULTS
We evaluated the prevalence of GHD given use of 1) local versus guideline cutoffs, 2) insulin tolerance test (ITT), pyridostigmine (PD)-GHRH or GHRH-arginine (arg) test, 3) single versus repeated testing, and 4) GH assessment by assays with different isoform specificities.


RESULTS
The prevalence of GHD was lower by local than by guideline cutoffs (12% vs 19% [PD-GHRH/GHRH-arg, P<.001]; 4.5% vs 5% [ITT, P=.9]), and by ITT than by PD-GHRH/GHRH-arg (P=.006 [local cutoffs]; P<.001 [guideline cutoffs]). Only 1% of patients had GHD according to 2 tests. GH assessment by the Immulite or iSYS assay caused no significant diagnostic differences.


CONCLUSIONS
The study confirmed a high risk of bias in the management of pituitary testing of patients with TBI and stresses the importance of a proper control group and stringent GH testing including confirmatory testing in cohorts with low a priori likelihood of GHD such as in TBI. Our results question the evidence for newly introduced recommendations for routine pituitary assessment in TBI.
Department of Medical Endocrinology (M.K., U.F.-R.), Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark; Department of Internal Medicine and Endocrinology (K.S., J.J., J.F., J.S.C.), Aarhus University Hospital, DK-8000 Aarhus, Denmark; Department of Medical Endocrinology (L.L.C., M.A.), Odense University Hospital, DK-5000 Odense, Denmark; and Department of Medical Endocrinology (P.L.), Aalborg University Hospital, DK-9100 Aalborg, Denmark.
Marianne
M
Klose
Kirstine
K
Stochholm
Jourgita
J
Janukonyté
Louise
L
Lehman Christensen
Jan
J
Frystyk
Marianne
M
Andersen
Peter
P
Laurberg
Jens Sandahl
JS
Christiansen
Ulla
U
Feldt-Rasmussen
D000293:Adolescent; D000328:Adult; D000368:Aged; D001930:Brain Injuries / Q000150:complications* / Q000453:epidemiology; D016022:Case-Control Studies; D003718:Denmark / Q000453:epidemiology; D003940:Diagnostic Techniques, Endocrine; D005260:Female; D019382:Human Growth Hormone / Q000172:deficiency*; D006801:Humans; D007018:Hypopituitarism / Q000175:diagnosis* / Q000453:epidemiology* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D055815:Young Adult
D019382:Human Growth Hormone