Endocrine Abstracts

Objectives: To determine the prevalence/aetiology/clinical significance of pituitary dysfunction following moderate/severe childhood traumatic brain injury (TBI).

Subjects: Twenty-six survivors of childhood TBI (20 males). Age at study: 5.4–18.9 year (median 13 year). Median time since TBI: 4.5y (2.3–6.7 year). King’s outcome scale for childhood head injury (KOSCHI) rating: 11 good recovery, 15 moderate disability, two severe disability.

Methods: Ethics committee approval was obtained. Subjects provided early morning urine samples for osmolality and underwent basal hormone evaluation at 0800–1000 h, followed by a GnRH test and either insulin tolerance test (ITT, n=20) or glucagon test (in those with previous seizures, n=6). Sex-hormone priming was not performed.

Results: No subject had clinical evidence of impaired growth (median height SDS +0.6, range −1.6 to +3.0). Peak growth hormone (GH) response to stimulation was 7.7 (2.5–15.8) (g/l. Sub-optimal responses (<5 μg/l) were observed in three peri-pubertal males (all tall: height SDS +0.8,+1.3,+1.39) and a borderline response in one post-pubertal male (3.18 μg/l).

No subject had diabetes insipidus. Thyroid function, IGF-I, oestradiol/testosterone, and baseline and GnRH-stimulated LH/FSH concentrations were all appropriate for age/sex/pubertal stage. One male had isolated prolactin deficiency (<50 mU/l).

Median basal morning cortisol was 296 (146–722) nmol/l. Peak cortisol response amongst subjects undergoing ITT was 533 (367–717) nmol/l. Of 7/20 had sub-optimal responses based on local age-related cut-offs, none low enough to warrant routine glucocorticoid replacement. In 2/7, steroid cover was recommended for moderate/severe illness/injury. In 4/7, repeat testing was advised; the seventh had high basal levels (624 nmol/l). Of 5/6 subjects had adequate cortisol responses to glucagon; the sixth, high basal levels (722 nmol/l).

Abnormal findings were unrelated to degree of primary/secondary brain injury or KOSCHI rating.

Conclusions: Whilst pituitary ‘dysfunction’ was common (39%), no unequivocal clinically significant endocrinopathies were found, although the GH/pituitary–adrenal axes may be vulnerable. Studies on larger numbers are underway.