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Open access

Marko Stojanovic, Zida Wu, Craig E Stiles, Dragana Miljic, Ivan Soldatovic, Sandra Pekic, Mirjana Doknic, Milan Petakov, Vera Popovic, Christian Strasburger, and Márta Korbonits

Background

Aryl hydrocarbon receptor-interacting protein (AIP) is evolutionarily conserved and expressed widely throughout the organism. Loss-of-function AIP mutations predispose to young-onset pituitary adenomas. AIP co-localizes with growth hormone in normal and tumorous somatotroph secretory vesicles. AIP protein is detectable in circulation. We aimed to investigate possible AIP and GH co-secretion, by studying serum AIP and GH levels at baseline and after GH stimulation or suppression, in GH deficiency (GHD) and in acromegaly patients.

Subjects and methods

Insulin tolerance test (ITT) was performed in GHD patients (n = 13) and age-BMI-matched normal GH axis control patients (n = 31). Oral glucose tolerance test (OGTT) was performed in active acromegaly patients (n = 26) and age-BMI-matched normal GH axis control patients (n = 18). In-house immunometric assay was developed for measuring circulating AIP.

Results

Serum AIP levels were in the 0.1 ng/mL range independently of gender, age or BMI. Baseline AIP did not differ between GHD and non-GHD or between acromegaly and patients with no acromegaly. There was no change in peak, trough or area under the curve during OGTT or ITT. Serum AIP did not correlate with GH during ITT or OGTT.

Conclusions

Human circulating serum AIP in vivo was assessed by a novel immunometric assay. AIP levels were independent of age, sex or BMI and unaffected by hypoglycaemia or hyperglycaemia. Despite co-localization in secretory vesicles, AIP and GH did not correlate at baseline or during GH stimulation or suppression tests. A platform of reliable serum AIP measurement is established for further research of its circulatory source, role and impact.

Open access

Marko Stojanovic, Zida Wu, Craig E Stiles, Dragana Miljic, Ivan Soldatovic, Sandra Pekic, Mirjana Doknic, Milan Petakov, Vera Popovic, Christian J Strasburger, and Marta Korbonits

Background: Aryl hydrocarbon receptor-interacting protein (AIP) is evolutionarily conserved and expressed widely throughout the organism. Loss-of-function AIP mutations predispose to young-onset pituitary adenomas. AIP co-localizes with growth hormone in normal and tumorous somatotroph secretory vesicles. AIP protein is detectable in circulation. We aimed to investigate possible AIP and GH co-secretion, through studying serum AIP and GH levels at baseline and after GH stimulation or suppression, in GH deficiency (GHD) and in acromegaly patients.

Subjects and methods: Insulin tolerance test (ITT) was performed in GHD patients (n=13) and age-BMI-matched normal GH axis control patients (n=31). Oral glucose tolerance test (OGTT) was performed in active acromegaly patients (n=26) and age-BMI-matched normal GH axis control patients (n=18). In-house immunometric assay was developed for measuring circulating AIP.

Results: Serum AIP levels were in the 0.1ng/ml range independently of gender, age or BMI. Baseline AIP did not differ between GHD and non-GHD or between acromegaly and patients with no acromegaly. There was no change in peak, trough or area under the curve during OGTT or ITT. Serum AIP did not correlate with GH during ITT or OGTT.

Conclusions: Human circulating serum AIP in vivo was assessed by a novel immunometric assay. AIP levels were independent of age, sex or BMI, and unaffected by hypoglycaemia or hyperglycaemia. Despite co-localization in secretory vesicles, AIP and GH did not correlate at baseline or during GH stimulation or suppression tests. A platform of reliable serum AIP measurement is established for further research of its circulatory source, role and impact.

Open access

Jose M Garcia, Beverly M. K. Biller, Marta Korbonits, Vera Popovic, Anton Luger, Christian J Strasburger, Philippe Chanson, Ronald Swerdloff, Christina Wang, Rosa Rosanna Fleming, Fredric Cohen, Nicola Ammer, Gilbert Mueller, Nicky Kelepouris, Frank Strobl, Vlady Ostrow, and Kevin Cj Yuen

Objective: The macimorelin test is approved for the diagnosis of adult growth hormone deficiency (AGHD) based on its efficacy vs the insulin tolerance test (ITT). Macimorelin has a significant advantage over ITT in avoiding hypoglycemia. Analyses were conducted to determine whether macimorelin performance is affected by age, body mass index (BMI), or sex, and evaluate its performance vs ITT over a range of GH cutpoints.

Design: Post hoc analyses of data from a previous randomized phase 3 study included participants aged 18-66 years with BMI <37 kg/m2 and high (Group A), intermediate (Group B), or low (Group C) likelihood for AGHD based on pituitary history, and matched controls (Group D).

Methods: Probability of AGHD was estimated using unadjusted, age-adjusted, BMI-adjusted, and sex-adjusted logistic models. Area under the curve (AUC) of the estimated receiver operating characteristic (ROC) curve (range, 0-1; 1=perfect) was compared for adjusted vs unadjusted models. Separate analyses evaluated agreement, sensitivity, and specificity for macimorelin and ITT using cutpoints of 2.8, 4.0, 5.1, and 6.5 ng/mL.

Results: For participants in Group A (n=41) and Group D (n=29), unadjusted, age-adjusted, BMI-adjusted, and sex-adjusted models had ROC AUCs (95% CIs) of 0.9924 (0.9807-1), 0.9924 (0.9807-1), 0.9916 (0.9786-1), and 0.9950 (0.9861-1), respectively.

Conclusions: Macimorelin performance was not meaningfully affected by age, BMI, or sex, indicating robustness for AGHD diagnosis. Of the 4 GH cutpoints evaluated, the cutpoint of 5.1 ng/mL provided maximal specificity (96%) and high sensitivity (92%) and was in good overall agreement with the ITT at the same cutpoint (87%).

Open access

Anita Hokken-Koelega, Aart-Jan van der Lely, Berthold Hauffa, Gabriele Häusler, Gudmundur Johannsson, Mohamad Maghnie, Jesús Argente, Jean DeSchepper, Helena Gleeson, John W Gregory, Charlotte Höybye, Fahrettin Keleştimur, Anton Luger, Hermann L Müller, Sebastian Neggers, Vera Popovic-Brkic, Eleonora Porcu, Lars Sävendahl, Stephen Shalet, Bessie Spiliotis, and Maithé Tauber

Objective

Seamless transition of endocrine patients from the paediatric to adult setting is still suboptimal, especially in patients with complex disorders, i.e., small for gestational age, Turner or Prader–Willi syndromes; Childhood Cancer Survivors, and those with childhood-onset growth hormone deficiency.

Methods

An expert panel meeting comprised of European paediatric and adult endocrinologists was convened to explore the current gaps in managing the healthcare of patients with endocrine diseases during transition from paediatric to adult care settings.

Results

While a consensus was reached that a team approach is best, discussions revealed that a ‘one size fits all’ model for transition is largely unsuccessful in these patients. They need more tailored care during adolescence to prevent complications like failure to achieve target adult height, reduced bone mineral density, morbid obesity, metabolic perturbations (obesity and body composition), inappropriate/inadequate puberty, compromised fertility, diminished quality of life and failure to adapt to the demands of adult life. Sometimes it is difficult for young people to detach emotionally from their paediatric endocrinologist and/or the abrupt change from an environment of parental responsibility to one of autonomy. Discussions about impending transition and healthcare autonomy should begin in early adolescence and continue throughout young adulthood to ensure seamless continuum of care and optimal treatment outcomes.

Conclusions

Even amongst a group of healthcare professionals with a great interest in improving transition services for patients with endocrine diseases, there is still much work to be done to improve the quality of healthcare for transition patients.