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Background: Bilateral inferior petrosal sinus sampling (BIPSS) has been the gold standard in differentiating a pituitary vs. an ectopic source of ACTH in Cushing’s syndrome however, it has many limitations. The ON-HDDST being simple to perform and the tests of choice in resource poor setting. The primary aim of our study was to consolidate the present knowledge regarding the diagnostic utility of ON-HDDST in localizing the source of ACTH. Method: We retrospectively studied 88 patients with ACTH dependent Cushing syndrome who underwent ONHDDST. Patient were considered as Cushing disease (CD) if either of the 3 criteria were met a) histopathological confirmed b) a central to peripheral gradient >2 was seen in BIPSS or c) pituitary adenoma ≥ 6mm seen in MRI of pituitary. Patient were considered as ectopic ACTH syndrome if the tumor was localized at any peripheral location by imaging or histopathological confirmed after surgery or if BIPSS shown a central to peripheral gradient of Result: Out of total 88 ACTH dependent Cushing syndrome patients, 68 (77.3%) were proven CD and 20 (22.7%) were ectopic. There was no difference in basal serum cortisol however, S. Cortisol after ONHDDST was significantly different between the two with a median of 547.7 nmol/l (341-770) in ectopic vs 273.5 nmol/l (142-689) in CD (p=0.02). A positive response to ONHDDST (≥50% suppression) was seen in about 44 (65%) patients with CD and 5 (25%) patients with ectopic disease (p = 0.002). Among CD patient, 35 (76.1%) of those with microadenoma, 7 (43.8%) amongst macroadenoma and 2 (33%) patient with no visible tumor on MRI shown positive response to ONHDDST. In ectopic group, cortisol suppressibility was seen in 3 (50%) patient with occult tumor but only in 2(14.3%) patient with. ROC curve plotted for percentage suppression of cortisol after ONHDDST shown as AUC equal to 0.68 (p = 0.01). The best test parameters with sensitivity (65%), specificity (85%) and Accuracy (69%) were seen at 50% cutoff level as were the likelihood ratio for positive test (4.3), AUC (0.75), PPV (93.6%), NPV (41.4%). Conclusion: Our study has shown that ONHDDST has poor diagnostic value in differentiating between CD and ectopic ACTH syndrome whatever be the cutoff level of the cortisol suppression. However, this can still be utilized in setups where no alternative is available. For etiologic confirmation, another test with better sensitivity and specificity is preferable.

Relevance. Cushing’s Syndrome (CS) is a serious risk factor for developing impaired glucose tolerance disorder (GTD) and a manifestation of secondary diabetes mellitus (DM). On the other hand, the development of impaired glucose metabolism affects not only the course but also the outcome of SC. Moreover, their frequency varies from 10% to 45% of all cases of SC. The aim of investigation - to evaluate the frequency of various forms of impaired glucose metabolism in patients with SC according to the national registry in the Republic of Uzbekistan. Materials and methods. The object of the study was 264 patients included in the register, 182 women (68.9%); men 82 (31.1%) aged 16 to 49 years. Including ACTH dependent CS (ACTH-DS) 219 (82.9%), ACTH independent CS (ACTH-IS) 41 (15.5%), ACTH ectopic CS (ACTH-ES) 4 (1.5%). The levels of ACTH, cortisol, insulin, glucose, glycated hemoglobin were studied, tests with dexamethasone and an oral glucose tolerance test (OGTT) were performed; MSCT of the adrenal gland and MRI of the pituitary gland. Fasting glucose (IH), NTG and diabetes were determined according to international criteria (EASD 2019, IDF 2018) Results. It was found that out of 264 patients with SC, 136 (51.5%) had various disorders of carbohydrate metabolism (CM), including diabetes in 32.6 ± 2.9% (86 bp), GTD in 18, 6 ± 2.4% (49 bp) and NGN - in 0.4 ± 0.4% (1 bp). At the same time, diabetes developed in 33.3% of cases in patients with ACTH-DS, 24.4% of ACTH-IS and 75% with ACTH-ESC (p˂ 0.01; p˂ 0.001). Cases of prediabetes were mainly found in the form of NTG in 17.4% of ACTH-DS and 26.8% in ACTH-IS. Conclusions. In the Republic of Uzbekistan, CM took place in the overwhelming majority of patients with CS (51.5%) and clearly depended on the type of CS (ACTH-ES, AKTG-DS, AKTG-IS) and correlated with the degree of hypercortisolism.

Background and objective: Hypercortisolism is the hall mark of ACTH Cushing’s syndrome, which is a benign ACTH secreting tumor resulting in high morbidity and mortality. The diagnosis is based on an elevated serum ACTH, elevated 24h urinary cortisol or a non-suppressible ACTH after dexamethasone suppression test. Confirmation of ACTH hypersecretion is followed by localization of the adenoma which can be pituitary in origin or peripheral. Dynamic MRI of the pituitary gland is the gold standard for diagnosis of pituitary tumors, and contrast enhanced CT scan is the gold standard for ectopic lesions which are usually lung tumors. The localization of the lesion is often a challenge because conventional MRI fail to show pituitary lesions and sometimes requiring inferior petrosal sinus sampling to confirm pituitary origin. Transsphenoidal surgery is the treatment of choice for Cushing’s disease, even without MRI evidence of pituitary tumors, if pituitary origin is confirmed by inferior petrosal sinus sampling. This causes increase in the incidence of treatment failure and complications. Thus, the diagnosis of Cushing’s disease urges exploring new diagnostic modalities. In our study we test the sensitivity of 11C methionine PET CT together with dynamic pituitary MRI in localization of ACTH dependent Cushing’s disease. Materials and methods This is an interventional, prospective study, forty-one subjects: newly diagnosed ACTH dependent Cushing’s Syndrome (n=29). (indicated by non-suppressible ACTH on dexamethasone suppression test) or persistent hypercortisolism following transsphenoidal surgery (n=12). 11C methionine PET CT was done in all cases in addition to dynamic pituitary MRI. All patients underwent 11 C-methionine PET-CT in addition to dynamic pituitary MRI This allowed us to determine whether suspected adenomas seen on structural imaging exhibited focal tracer uptake on functional imaging.Inclusion Criteria:• Aged 18 years old or over• Patient with a diagnosed Cushing’s disease confirmed by non-suppressible ACTH on dexamethasone suppression test.• Patient with persistent ACTH dependent Cushing’s disease following transsphenoidal surgery.• Patient not enrolled in other interventional studies.Exclusion Criteria:• Contraindication to MRI• Pregnant woman, breastfeeding RESULTS: Patients with newly diagnosed ACTH dependent Cushing: 24 out of 29 of the cases showed adenoma on dynamic MRI of the pituitary; 5 out of 29 cases failed to showed any lesions on dynamic MRI of the pituitary; Inferior petrosal sampling was done and confirmed pituitary origin in 4 out of 5 and 1 out of 5 was found to have ectopic ACTH secretion. In patients with persistent hypercortisolism following transsphenoidal surgery; 3 out of 12 of the cases showed adenoma on dynamic MRI of the pituitary and 7 out of 12 cases failed to showed any lesions on dynamic MRI of the pituitary and inferior petrosal sampling was done and confirmed pituitary origin in all 12 cases. All 41 cases underwent 11C methionine PET CT scan; 39 patients showed tracer uptake on 11c methionine PET CT scan in the pituitary area, 36 of which had unilateral asymmetrical tracer uptake. All 40 subjects with suspected pituitary lesions were confirmed to be of pituitary origin by histopathological examination of biopsies taken intraoperatively. CONCLUSIONS 11C methionine PET CT has proven to be of very high sensitivity in detecting ACTH secreting adenomas, further studies should be done on a larger scale as this modality can address the pitfalls in localization of ACTH secreting lesions.

Data on the impact of withdrawal from long-acting somatostatin receptor ligand (SRL) injections on disease activity in patients with acromegaly are limited. The phase 3 Octreotide capsules versus Placebo Treatment In MultinationAL centers (OPTIMAL) study assessed the efficacy and safety of oral octreotide capsules in adult patients with acromegaly responding to injectable SRL therapy. The placebo-controlled arm of this study allowed for assessment of acromegaly biochemical and disease activity in patients after withdrawal from SRL treatment. A multinational, randomized, placebo-controlled study was conducted in 56 adult patients with active acromegaly. Patients were ≥ 18 years of age, had evidence of active disease (defined as IGF-I ≥1.3 x ULN after last pituitary surgery), and an average IGF-I ≤ 1.0 x ULN in response to a stable dose of SRL injection. Patients were randomized, 1 month following their last injection, to octreotide capsule or placebo for 36 weeks, with an option to enroll in an open-label extension. The primary aim was to determine the proportion of patients maintaining biochemical response, defined as IGF-I ≤1.0 x ULN (average of week 34 and 36). The trial met the primary endpoint, with 58% (16/28) of patients receiving octreotide capsules maintaining IGF-I response vs 19% (5/28) receiving placebo (P=0.008). The median time to loss of response (2 criteria evaluated: IGF-I >1.0 and ≥ 1.3 x ULN for 2 consecutive visits) was 16 weeks in the placebo group, while it was not reached in the octreotide capsule group. Of the 5 patients in the placebo group who maintained their biochemical response at 36 weeks, only 2 (7% of placebo group) did not meet loss of response criteria. When IGF-I values for any 2 consecutive visits were analyzed for patients receiving placebo, 93% (26/28) lost response based on IGF-I > 1 x ULN and 79% (22/28) lost response based on IGF-I ≥ 1.3 x ULN. Irrespective of biochemical control of acromegaly, 26/28 patients receiving placebo experienced active disease-related symptoms reported as AEs of special interest (AESIs). Most common AESIs (≥ 5%) included arthralgia/arthritis (60.7%), soft tissue swelling (35.7%), headache (32.1%), hyperhidrosis (25%), carpal tunnel (14.3%), musculoskeletal pain (14.3%), weight increased (7.1%) and tongue disorders (7.1%). The 5 patients receiving placebo with controlled IGF-I at 36 weeks received active medical treatment in the open label extension by decision of their study PIs, as they were deemed to have either lost their response during the study or had continuing active acromegaly symptoms. 93% of patients receiving placebo lost response following withdrawal of injectable SRLs, with a median duration of 16 weeks. All 5 patients receiving placebo who met the primary endpoint criteria at the end of the study were assessed clinically to have active disease and were continued on oral SRL treatment in the open label extension.

Introduction: Acromegaly (Acro) is a systemic disease characterized by high growth hormone (GH) and insulin like growth factor-I (IGF-I), insulin resistance, glucose intolerance (IGT) and higher diabetes mellitus (DM) risk in 15% - 38% of patients (pts). Moreover, different medical therapies of Acro are reported to have variable effects on glucose metabolism. An association between blood glucose (BG) and serum IGF-I levels in patients with DM and Acro has been suggested, while IGF-I levels and hemoglobin A1c (HbA1c) correlation is still controversial because of the multifactorial influence.Study aim: to investigate glucose metabolism in pts with Acro resistant to 1st gen somatostatin receptor ligands (SRLs) treated with Pegvisomant (Peg) or Pasireotide LAR (Pasi). Patients and Methods: Retrospective, international, multicenter study; consecutive pts enrolled according to following inclusion criteria for at least 6 consecutive months: (1) resistant to 1st gen SRLs, (2) treated with Pasi or Peg for active Acro. Patients with concomitant treatments with known action on glucose metabolism were excluded, with the exception of glucocorticoid replacement for central hypoadrenalism. Results: 72 pts with active Acro, mean age at study entry 37 ±15 yrs, 47 females (65.3%). 28 (38.9%) pts were treated with Pasi and 44 pts with Peg (61.1%). Peg was monotherapy in 18 pts (40.9%) and in combo with first generation SRLs for 26 pts (59.1%). The number of pts with IGT and DM2 was superimposable between the 2 groups (Pasi and Peg). In Pasi group, 19 pts had Acro control (67.9%); glucose metabolism worsened in 16 pts (57.1%). Worsening of glucose metabolism occurred most frequently in pts with persistently active Acro (62.5%) and in pts with higher BG and HbA1c values at study start. Similarly, HbA1c was higher in pts with active Acro, although HbA1c worsened during Pasi treatment both in euglycemic and IGT at study entry, regardless of Acro control. In Peg group, 31 pts reached Acro control (73%); glucose metabolism worsened in 12 (27.3%) but improved in 5 pts (11.4%). All pts who experienced glucose metabolism improvement had controlled Acro, regardless of the use of a combo with first generation SRL. Among the 13 pts with active Acro after Peg, BG worsened in 5 cases (38.4%). Moreover, we found that pts with worsening BG control had higher HbA1c (p=0.03) and required higher Peg doses (mean ±SD 25 ±10 mg/day; p=0.04). Patients with higher HbA1c had higher IGF-I, both at study entry and at study end and were treated with higher Peg dose (mean 25 mg/day). Conclusion: Impaired glucose metabolism was more frequent after Pasireotide treatment and in patients of both Pasireotide and Pegvisomant groups with altered pre-treatment glucose and persistently active disease. Therefore, in such acromegaly patients close monitoring of glucose status is recommended during treatment.

Introduction: Prolactinomas are the most frequent pituitary-secreting tumors. Medical therapy with cabergoline (CAB), a dopamine agonist (DA), is the first line treatment, but 10% of prolactinomas are resistant to CAB. Recently, in vitro studies have shown anti-tumoral activity of metformin and other biguanids in human prolactinomas1, which prompted us to investigate that possibility in vivo. Aim: To evaluate the effect of metformin (MET) on Prolactin (PRL) secretion in patients with CAB resistant prolactinomas. Design and Setting: Prospective interventional study in a single referral center. Subjects: Ten patients (7 M; mean age: 44 ± 12y) with CAB resistant (PRL: 148 ± 125ng/ml; range: 38 - 386) prolactinomas (all macroadenomas) and metabolic syndrome on maximally tolerated CAB doses (4.3 ± 1.2 mg/week; range: 2.0-7.0) for ≥ 6 months (45 ± 39mo; range: 6-120). Intervention: Oral extended release metformin (p.o.) was prescribed according to patient’s tolerance (mean dose: 1.3 ± 0.4 g; range: 1.0-2.0). Main Outcome Measurements: Serum PRL (Elecsys, Roche, Indianapolis, USA), body weight (BW), fasting glycemia (FG) and HbA1C were evaluated before and at two time points during metformin treatment (30-60 and 120-180 days). Results: BW, FG, and/or HbA1C reductions were observed in 9/10 patients and mean FG decreased significantly (P=0.04). No significant changes were observed in serum PRL levels during metformin treatment [134 ± 124 ng/ml vs 138 ± 132 ng/ml vs 144 ± 129 ng/ml, before, at 30-60 days and at 120-180 days, respectively (P=0.499, mixed-effects analysis with the Geisser-Greenhouse correction)]. Individually, two patients exhibited a ≥ 50% decrease in PRL levels at a single timepoint (one at 30-60 days, with a further increase at 120-180 days and the other at 120-180 days). Conclusion: Metformin, at usual doses, did not inhibit prolactin secretion in patients with cabergoline-resistant prolactinomas. The discrepancy between our results and in vitro studies is not clear, but may be related to the much higher concentrations of metformin used in vitro1 as compared to the serum concentrations observed in patients during metformin treatment2. References: 1Gao J et al. Metformin inhibits growth and prolactin secretion of pituitary prolactinoma cells and xenografts. J Cell Mol Med. 2018 22:6368-79; 2 Frid A et al. Novel assay of metformin levels in patients with type 2 diabetes and varying levels of renal function: clinical recommendations. Diabetes Care 2010 33:1291-3.

Background: In clinical practice, most patients responding to injectable somatostatin receptor ligands exhibit IGF-I variability around the upper limit of normal (ULN) during long-term follow up. These fluctuations are thought to result from various factors such as assay variability, nutrition, comorbid conditions, concomitant medications and other unknown factors. The magnitude of this variability, and the factors affecting it, is not well understood in patients with acromegaly treated with injectable SRLs. Methods: IGF-I levels of patients responding to and stably treated with injectable SRLs were measured over time in the CHIASMA OPTIMAL phase III study. Two time periods were assessed - Period 1, three assessments during screening phase before randomization to octreotide capsules (N=56), and Period 2 - multiple assessments up to week 36, in patients rescued with SRL injections for at least 12 weeks (N=21). The time from the last injection to each of the 3 assessments in period 1 [Screening visits 1 and 2 (SV1 & SV2), and Baseline (BL)], was on average 6.8 ± 10.7 (SD), 15.8 ± 2.7, and 29.0 ± 1.8 days respectively. Correlation with various demographics and Baseline characteristics, including age, gender, weight, BMI and residual tumor size to IGF-I variability was assessed. Percent change for each individual patient from Minimal to Maximal IGF-I values within each period was computed and the overall population mean was calculated (lowest value was used as the denominator and all other values were expression as a positive % above this value). Results: The overall mean within-patient percent change of IGF-I levels during Period 1 was 20.48 ± 15.56 (range: 0.6-81). Mean IGF-I levels for SV1, SV2 and BL were 0.78 ± 0.18, 0.79 ± 0.18, and 0.85 ± 0.22 x ULN respectively. The overall increase in mean IGF-I levels from SV1 to BL (longest time interval) was statistically significant (p=0.0002; paired T-test). Analysis of IGF-I levels in patients during Period 2, revealed that the overall mean within-patient percent change of IGF-I levels was 15.27 ± 12.20 (range: 0-41.5). The mean duration of follow up during this period, after patients were already treated for ≥12 weeks with injectable SRL, was 1.72 (± 1.29) months. The variability observed in Period 2 was similar to that observed in the entire sample evaluated in Period 1. No significant differences were found in the mean IGF-I percent change between any demographic or baseline characteristic subgroup examined. Conclusion: IGF-I levels fluctuate in patients with acromegaly who are responsive to injectable SRLs. These fluctuations are wide and can be up to 81% higher than the lowest (most controlled) value, with an average increase of approximately 20%. Significant IGF-I increases were observed at the end of the long acting SRL injection interval. Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. Abstracts presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.

The prevalence of growth hormone (GH)-secreting pituitary adenoma is around 11-13% of all pituitary adenomas. Giant GH-secreting pituitary adenomas (≥ 4 cm) are rare tumors, and its prevalence of among acromegalic patients is This is a retrospective cohort study including patients with giant GH-secreting pituitary adenomas. The study population consisted of 10 patients (5 M/5 F). The mean age at diagnosis was 33.0±12.9 yrs (11-55 yrs). The mean delay between first symptom onset and diagnosis was 2.9 years. The most frequent symptoms were acral enlargement and facial changes (80%), followed by headache (70%) and visual deterioration (50%). One patient had epilepsy. Amenorrhea was presented in three females but obvious galactorrhea in two. The mean adenoma diameter was 42.6±4.7 mm (40-51 mm) at diagnosis. The vast majority of adenomas presented suprasellar extension (100%) or cavernous sinus invasion (80%). Cystic adenomas accounted for 50%. At presentation, mean GH and IGF-1 levels were 40.0±21.4 ng/mL (14.8-51.0) and 2.62±1.09 x ULN (1.08-3.96), respectively. Six patients presented with PRL cosecretion. At diagnosis maximal tumor diameter was not correlated with GH or IGF-1 levels. All patients underwent pituitary surgery as first-line treatment. Three cases were treated with an endoscopic approach and four cases with a microscopic approach. Transcranial approach was also employed in three cases. Postoperative mean GH and IGF-1 levels were 14.9±16.1 ng/mL (0.6-51.0) and 2.25.±0.82 x ULN (1.48-3.74), respectively. After first surgery, only one patient had more than 50% reduction in IGF-1 levels. Five patients (50%) underwent repeat surgery on two to three procedures because remission was not achieved. Postoperative somatostatin receptor ligands (SRLs) were used by all patients. Six patients were treated with dopamine agonist in combination with SRL. Six patients (60%) received postoperative radiotherapy. The mean follow-up period was 12.6±5.3 yrs (4-21 yrs). The mean GH and IGF-1 levels were 1.47±1.54 ng/mL (0.08-5.25) and 0.73±0.44 x ULN (0.08-1.56), respectively at the last visit. Residual adenoma was present at the last MRI in eight patients (mean diameter 9.0±3.6 mm). Panhypopituitarism rose from 10% at baseline to 30% at the last visit. During follow-up, one patient diagnosed breast cancer, while another diagnosed thyroid papillary cancer. Giant GH-secreting pituitary adenomas can have a clinically aggressive behavior with mass effect. Moreover, treatment in patients with giant GH-secreting pituitary adenoma is complex and multimodal therapy is necessary.

Cushing’s disease (CD) is characterized by chronic exposure to excess glucocorticoids due to an ACTH-producing tumor. Obesity is a prominent feature of CD, although the mechanisms of weight gain have not been completely elucidated. In some patients, obesity persists despite appropriate medical or surgical treatment of CD and normalization of cortisol levels (1). Few studies have followed patients prospectively to understand the effect of CD remission and cortisol normalization on appetite and body weight. Previous studies have not shown a correlation between appetite or food cravings and circulating total peptide YY (PYY), ghrelin, or leptin concentrations, leading to interest in other hormones which may regulate appetite in CD (2). One of these is the neuropeptide Agouti-related protein (AgRP). AgRP is known to promote appetite and decrease energy expenditure by acting as a melanocortin antagonist at the level of the hypothalamus. Plasma AgRP may be elevated in patients with active CD and decreases with normalization of cortisol levels (3). We sought to determine if AgRP may play a role in regulating appetite or food cravings in CD. Plasma AgRP was measured before and prospectively after treatment in 19 patients with CD. Patients completed surveys on appetite and food cravings at these same time points. As expected, AgRP significantly decreased following treatment for CD, with mean AgRP before treatment 128.72 pg/mL (SD 55.41) and mean AgRP after treatment 75.23 pg/mL (SD 23.46). Using a paired t-test, the mean difference of 53.5 pg/mL was significant (p=0.0006). In addition, there were significant decreases in BMI, weight, and waist circumference with CD treatment. We found that plasma AgRP concentrations did not correlate with an 8-question visual analogue scale (VAS) used to assess hunger and satiety. However, treatment of CD significantly reduced Trait Food Craving Questionnaire scores in parallel with circulating AgRP levels using a one-way analysis of variance (p=0.004). Our data suggest that AgRP may play a role in food craving, rather than appetite, in patients with CD. Further research may clarify the relationship between AgRP and food cravings in CD patients before and after treatment. References: 1. Geer et al. Endocrinol Metab Clin North Am. 2014; 43: 75-102. Geer et al. Pituitary. 2016; 19: 117-126.Page-Wilson et al, J Clin Endocrinol Metab. 2019; 104 (3): 961-969.

Silent corticotroph adenomas (SCAs) are tumors of the TPIT anterior pituitary cell lineage that do not lead to biochemical or clinical Cushings syndrome. Thus, they present as clinically nonfunctioning pituitary adenomas (CNFPAs) and are only diagnosed pathologically. Since they are often aggressive tumors, identification of a peripheral blood marker of SCA activity would be useful for diagnosis and monitoring. Some data suggest that aberrant processing of POMC, the precursor of ACTH, underlies the lack of elevated biologically active ACTH and thus cortisol excess in SCAs. We hypothesized that these tumors could secrete POMC, resulting in elevated plasma levels of POMC in patients with SCAs. Therefore, we investigated plasma POMC levels as a potential marker of this tumor type and correlated with tumor ACTH immunoreactivity (IR), which may be detecting unprocessed POMC. We studied 267 patients (134M, 133F, age 56.3±13.6yr) with CNFPAs (Cushings excluded) prior to surgery and at enrollment in a prospective, observational study. We also studied 9 patients with known SCAs with residual macroadenomas after surgery. Peripheral blood was sampled for POMC, ACTH and cortisol levels. POMC was measured by in-house two-site ELISA (detects POMC and 22kD pro-ACTH) and ACTH and cortisol by Immulite(Siemens). POMC levels were compared to the 95%CI of the mean of 70 healthy subjects and considered elevated if ≥ the 97.5 percentile of 39 fmol/mL. Of the CNFPA cohort, 12/267 had elevated POMC levels (range 39-166 fmol/mL) and 4 of the 12 had elevated ACTH levels (> 50 pg/ml)(range 53.6-76 pg/ml). Of the 12 with elevated POMC, 9 underwent surgery and 6 of them had positive ACTH IR in their tumors. An additional 13 patients in the CNFPA cohort had weak ACTH IR tumors, but POMC