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DOI: 10.1055/s-2007-972341
Prevalence of anterior pituitary dysfunction in patients following traumatic brain injury (TBI) in a German multi-centre screening program
Recent data suggest that hypopituitarism is a common complication of TBI. Prevalence differs between 10–40% and is based on different diagnostic tests and criteria. Hence, under field conditions TBI-mediated hypopituitarism may be less frequent than previously thought. We determined the prevalence of anterior pituitary dysfunction in a multi-centre screening program across five German endocrine centres in patients rehabilitating from TBI (GCS<13).
246 patients (43±14yrs; 133 males, 12±8 after TBI) underwent a series of baseline endocrine tests with central assessment of TSH, free T4, prolactin, LH, FSH, testosterone (m), estradiol (f), cortisol, GH, and IGF-I.
If IGF-I was < -1 SDS dynamic testing was performed. GHD was defined according to BMI-dependent cut-off values for GH response to GHRH+arginine of <4.2, <8.0 and <11.5 ng/ml in obese, overweight and lean subjects, respectively, and <3 microg/L in ITT. Hypocortisolism was defined when basal cortisol was <200 nmol/l and confirmed by ITT (peak <500 nmol/l).
In TBI patients some degree of impaired pituitary function was shown in 21% (n=52/246). Total, multiple and isolated deficits were present in 1%, 2% and 18%, respectively.
19% (n=46) had an IGF-I of < -1 SDS. IGF-I did not correlate with BMI, gender or time after injury, but with age (p=0.03). In 4% (n=9) GHD was confirmed. 9% (n=23) had hypogonadism (total testosterone <9.5 nmol/L / low estradiol and low gonadotropins in 17 males/ 6 females). 4% (n=11) had hypocortisolism and 1% (n=3) of patients had confirmed ACTH-deficiency (cortisol-peak [ITT] 392, 401 and 417 nmol/L). 12% (n=29) had TSH-deficiency.
In summary, in this large series carried out on an unselected group of TBI survivors we could not confirm a high prevalence of anterior pituitary dysfunction after 12 months. Only every fifth patient with low IGF-I had confirmed GHD according to strict criteria and based on BMI-dependent cut-offs for GHRH/arginine testing. Hence IGF-I is a poor predictor for GHD in TBI.