ECE2017 Guided Posters Pituitary & endocrine Tumours (12 abstracts)
Diagnosis of acromegaly: Sex and BMI are the major determinants of growth hormone suppression during oral glucose tolerance test (OGTT)
Katharina Schilbach , Shiva Sophia Nicolay , Michael Haenelt , Andreas Lechner , Christina Gar , Jochen Schopohl , Sylvère Störmann , Rita Schwaiger & Martin Bidlingmaier
Medizinische Klinik und Poliklinik IV, Klinikum der Universität München, Munich, Germany.
GH suppression during OGTT is the gold-standard test in diagnosis and monitoring of acromegaly. However, discrepancies between GH nadir and IGF-I have been described and have triggered search for factors modifying the extent of GH suppression. Cut-offs at 1.0 or 0.4 ng/ml are currently recommended with modern, highly sensitive GH assays. To establish assay specific GH nadir cutoffs for the 22kD GH specific IDS-iSYS assay, we examined 381 subjects (319 females, 62 males) with normal pituitary function. We analyzed the impact of age, body mass index (BMI), menstrual cycle and hormonal contraceptive therapy.
In 96% of all subjects the GH nadir was <0.4 ng/ml (92% <0.3 ng/ml, 81% <0.2 ng/ml and 56% <0.1 ng/ml). In all sex- and age-groups BMI was the major determinant, with lower GH nadirs in subjects with higher BMI. In 4 different BMI groups (A: <20 kg/m2, n=30, B: 20–25 kg/m2, n=174, C: 25–30 kg/m2, n=99 and D: >30 kg/m2, n=77) mean GH nadirs were as follows: A: 0.29 ng/ml, B: 0.15 ng/ml, C: 0.10 ng/ml and D: 0.07 ng/ml with significant differences between all groups except group C vs. D (A vs. B: P=0.0043, A vs. C, A vs. D, B vs. C, B vs. D: P<0.0001, C vs D: P=0.057). While age had no impact, men exhibited significantly lower mean GH nadirs compared to women (0.09 vs 0.14 ng/ml, P<0.0001). Premenopausal women on estrogen containing oral contraception (OC) (n=20) had significantly higher mean GH nadirs (0.36 ng/ml) compared to women not taking estrogen containing OC (n=272, 0.13 ng/ml, P<0.044), while the phase of the menstrual cycle had no impact.
Our findings confirm the need for lower cutoffs for the GH nadir if new sensitive GH assays are used, but also suggest adjustment to sex- and BMI can improve diagnostic sensitivity and specificity.
Volume 49
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Endocrine Abstracts
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