Bilateral pheochromocytoma: Clinical characteristics, treatment and longitudinal follow-up.

OBJECTIVE: Comprehensive data about patients with bilateral pheochromocytoma are limited. We aimed to describe the clinical presentation, genetic analysis, treatment and outcomes of patients with bilateral pheochromocytoma. DESIGN: A retrospective study at a tertiary care centre. PATIENTS: All patients with bilateral pheochromocytoma evaluated at Mayo Clinic in Rochester, Minnesota between January 1951 and December 2015. MEASUREMENTS: Tumour size, genetic testing, plasma/urine metanephrines and catecholamines. RESULTS: A total of 94 patients (51% women) were diagnosed with bilateral pheochromocytoma at a median age at first presentation of 31 years (range, 4-70). Bilateral disease was noted in 8.0% of pheochromocytoma patient overall and 37.5% of patients 18 years of younger. Most patients presented with synchronous tumours (80%). Median time to metachronous tumours was 4.5 years (range, 1-38). Genetic disease was identified in 75 (80%) patients, including MEN 2A (42.6%), VHL (19.1%), MEN 2B (9.6%) and NF1 (8.5%). Excess catecholamines were present in 97% of patients. Patients with synchronous pheochromocytoma commonly underwent simultaneous bilateral adrenalectomy (99%), and 18 (24%) had cortical-sparing surgery. Multicentric tumours were reported in 23 of 77 (30%) patients with available data. Recurrent disease was found in 9.6% of patients, and 8.5% developed metastatic disease. Median follow-up was 8.5 years. At the study conclusion, 4 patients had died due to pheochromocytoma or adrenalectomy. CONCLUSIONS: Bilateral pheochromocytoma occurred in 7.0% of adults with pheochromocytoma and 37.5% of paediatric patients. Genetic disease was identified in 80% of patients, predominantly MEN2A. Multicentric tumours were common, but most were still cured following adrenalectomy.

Assessment of The Bethesda System for Reporting Thyroid Cytopathology.

OBJECTIVES: Long-term follow-up is important for determining performance characteristics of thyroid fine-needle aspiration (FNA). METHODS: Histologic or 3 or more years of clinical follow-up was used to calculate performance characteristics of thyroid FNA before and after implementation of The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC). The impact of noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) classification was also investigated. RESULTS: Follow-up was obtained for 1,277/1,134 and 1,616/1,393 aspirates/patients (median clinical follow-up, 9.9 and 4.4 years, pre- and post-TBSRTC, respectively). Nondiagnostic, suspicious for follicular neoplasm, and suspicious for malignancy (SFM) diagnoses decreased and benign diagnoses increased post-TBSRTC, while atypical rate remained less than 1%. Negative predictive value for benign nodules and positive predictive value (PPV) for SFM increased significantly. Eleven nodules were reclassified as NIFTP, slightly decreasing PPV/risk of malignancy (ROM). CONCLUSIONS: Appropriate ROM for thyroid FNA can be achieved through application of TBSRTC terminology with minimal use of atypical category.

MANAGEMENT AND OUTCOMES OF GIANT PROLACTINOMA: A SERIES OF 71 PATIENTS.

Objective: To describe outcomes of patients with giant prolactinoma (≥4 cm) and identify predictors of therapeutic response. Methods: In this retrospective study, complete biochemical and structural response were defined as prolactin (PRL) ≤25 ng/mL and no visible tumor at follow-up, respectively. Results: Giant prolactinoma (median size, 4.8 cm [range, 4 to 9.8 cm]; median PRL, 5,927 ng/mL [range, 120 to 100,000 ng/mL]) was diagnosed in 71 patients. Treatments included: dopamine agonists (DAs) (n = 70, 99%), surgery (n = 30, 42%), radiation (n = 10, 14%), and somatostatin analogs (n = 2, 3%). Patients treated with DA monotherapy were older compared with those who received subsequent therapies (47 years vs. 28 years; P = .003) but had similar initial PRL and tumor size. Surgically managed patients were younger compared with the nonsurgical group (35 years vs. 46 years; P = .02) and had lower initial PRL (3,121 ng/mL vs. 6,920 ng/mL; P = .02), yet they had similar tumor response. Hypopituitarism was more common following surgery compared to medical management: adrenal insufficiency (69% vs. 27%; P<.001), hypothyroidism (67% vs. 38%; P = .02), growth hormone deficiency (24% vs. 6%; P = .04), and diabetes insipidus (17% vs. 3%; P = .04). Therapeutic response did not correlate with sex, age, initial PRL, tumor size, or first-line therapy mode. At median follow-up of 4.8 years, the median PRL was 18.3 ng/mL (range, 0.6 to 12,680 ng/mL), and final volume was 0.9 cm3 (range, 0 to 43.0 cm3). In those with available data, 36/65 (55%) patients achieved PRL normalization, and 16/61 (26%) had no visible tumor at follow-up. Conclusion: Most patients with giant prolactinoma have excellent response to DA. Sex, age, initial PRL, and tumor size do not predict therapeutic response. Abbreviations: BRC = bromocriptine; CAB = cabergoline; CSF = cerebrospinal fluid; DA = dopamine agonist; MRI = magnetic resonance imaging; PRL = prolactin.

Assessment of pulsatile insulin secretion derived from peripheral plasma C-peptide concentrations by nonparametric stochastic deconvolution.

The characteristics of pulsatile insulin secretion are important determinants of type 2 diabetes pathophysiology, but they are understudied due to the difficulties in measuring pulsatile insulin secretion noninvasively. Deconvolution of either peripheral C-peptide or insulin concentrations offers an appealing alternative to hepatic vein catheterization. However, to do so, there are a series of methodological challenges to overcome. C-peptide has a relatively long half-life and accumulates in the circulation. On the other hand, peripheral insulin concentrations reflect relatively fast clearance and hepatic extraction as it leaves the portal circulation to enter the systemic circulation. We propose a method based on nonparametric stochastic deconvolution of C-peptide concentrations, using individually determined C-peptide kinetics, to overcome these limitations. The use of C-peptide (instead of insulin) concentrations allows estimation of portal (and not post-hepatic) insulin pulses, whereas nonparametric stochastic deconvolution allows evaluation of pulsatile signals without any a priori assumptions of pulse shape and occurrence. The only assumption required is the degree of smoothness of the (unknown) secretion rate. We tested this method first on simulated data and then on 29 nondiabetic subjects studied during euglycemia and hyperglycemia and compared our estimates with the profiles obtained from hepatic vein insulin concentrations. This method produced satisfactory results both in the ability to fit the data and in providing reliable estimates of pulsatile secretion, in agreement with hepatic vein measurements. In conclusion, the proposed method enables reliable and noninvasive measurement of pulsatile insulin secretion. Future studies will be needed to validate this method in people with type 2 diabetes.

GH Therapy in Childhood Cancer Survivors: A Systematic Review and Meta-Analysis.

Background: GH deficiency (GHD) is common among childhood cancer survivors (CCSs) with history of tumors, surgery, and/or radiotherapy involving the hypothalamus-pituitary region. We aimed to evaluate the effects of GH therapy (GHT) in CCSs on adult height, risk of diabetes mellitus, abnormal lipids, metabolic syndrome, quality of life, secondary tumors, and disease recurrence. Methods: We searched multiple databases for randomized and observational studies. Pairs of reviewers independently selected studies and collected data. Random effects meta-analysis was used to pool outcomes across the studies. Results: We included 29 observational studies at moderate to high risk of bias. Sixteen studies compared CCSs on GHT with those not on GHT (512 patients, GH dose: 0.3 to 0.9 IU/kg/week). GHT was significantly associated with height gain [standard deviation score, 0.61; 95% CI, 0.08 to 1.13] and was not significantly associated with the occurrence of secondary tumors [odds ratio (OR), 1.10; 95% CI, 0.72 to 1.67] or tumor recurrence (OR, 0.57; 95% CI, 0.31 to 1.02). Thirteen studies compared CCSs on GHT with normal age- or sex-matched controls or controls with idiopathic GHD or short stature. GHT was associated with either improved or unchanged risk of diabetes, lipid profiles, and metabolic syndrome. GHT was associated with improvements in quality of life. Conclusion: CCSs treated with GHT gain height compared with the untreated controls. GHT may improve lipid profiles and quality of life and does not appear to increase the risk of diabetes or the development of secondary tumors, although close monitoring for such complications remains warranted due to uncertainty in the current evidence.

Diagnosis of GH Deficiency as a Late Effect of Radiotherapy in Survivors of Childhood Cancers.

Background: Limited guidance exists for selecting a laboratory method for diagnosing GH deficiency (GHD) when it occurs as a late effect of radiotherapy in childhood cancer survivors (CCSs). Methods: We searched Medline, Embase, Cochrane Central Register of Controlled Trials and Database of Systematic Reviews, and Scopus for studies evaluating GHD that used IGF-1 or IGF-binding protein 3 (IGFBP-3) measurements compared with GH dynamic testing. Results: We included 15 studies [IGF-1 (8 studies) and IGFBP-3 (7 studies)] enrolling 477 patients. Comparator tests varied widely. Overall, both IGF-1 and IGFBP-3 had suboptimal diagnostic accuracy but were strongly correlated. The use of both tests simultaneously in the same cohort did not improve the diagnostic accuracy. Despite high variability in the testing protocols, dynamic tests remained the most accurate for appropriately identifying patients with GHD. The insulin tolerance test (ITT) appears to be the most accepted reference test when used alone or in combination with arginine; however, standardized testing strategies among practice groups are absent. GHRH and arginine stimulation performed almost similarly to the ITT; however, in one study GHRH with arginine stimulation had 66% sensitivity and 88% specificity compared with the ITT. Insufficient data were available to assess the accuracy of serial GH testing (nocturnal or over 24 hours). Conclusion: The diagnostic accuracy of various dynamic tests for GHD in CCSs appears to follow the same patterns as those in non-CCSs. Interpreting GHRH stimulation is a challenge given the primarily hypothalamic dysfunction in CCSs. IGF-1 and IGFBP-3 perform poorly in this population.

Malignant Pheochromocytoma and Paraganglioma: 272 Patients Over 55 Years.

Context: Malignant pheochromocytoma (PHEO) and paraganglioma (PGL) are rare and knowledge of the natural history is limited. Objective: We aimed to describe baseline characteristics and outcomes of patients with malignant PHEO and PGL (PPGL) and to identify predictors of shorter survival. Design: Retrospective review of patients with malignant PPGL evaluated from 1960 to 2016. Setting: Referral center. Patients: The group comprised 272 patients. Main Outcome Measures: Baseline description, survival outcomes, and predictors of shorter survival were evaluated in patients with rapidly progressive (n = 29) and indolent disease (n = 188). Results: Malignant PPGL was diagnosed at a median age of 39 years (range, 7 to 83 years), with synchronous metastases in 96 (35%) patients. In 176 (65%) patients, metastases developed at a median of 5.5 years (range, 0.3 to 53.4 years) from the initial diagnosis. Median follow-up was 8.2 years (range, 0.01 to 54.1 years). Median overall and disease-specific survivals were 24.6 and 33.7 years, respectively. Shorter survival correlated with male sex (P = 0.014), older age at the time of primary tumor (P = 0.0011), synchronous metastases (P < 0.0001), larger primary tumor size (P = 0.0039), elevated dopamine (P = 0.0195), and not undergoing primary tumor resection (P < 0.0001). There was no difference in the type of primary tumor or presence of SDHB mutation. Conclusions: The clinical course of patients with malignant PPGL is remarkably variable. Rapid disease progression is associated with male sex, older age at diagnosis, synchronous metastases, larger tumor size, elevated dopamine, and not undergoing resection of primary tumor. An individualized approach to patients with metastatic PPGL is warranted.

MANAGEMENT OF ENDOCRINE DISEASE: Pathogenesis and management of hypoglycemia.

Glucose is the main substrate utilized by the brain and as such multiple regulatory mechanisms exist to maintain glucose concentrations. When these mechanisms fail or are defective, hypoglycemia ensues. Due to these robust mechanisms, hypoglycemia is uncommon and usually occurs in the setting of the treatment of diabetes using glucose-lowering agents such as sulfonylureas or insulin. The symptoms of hypoglycemia are non-specific and as such it is important to confirm hypoglycemia by establishing the presence of Whipple's triad before embarking on an evaluation for hypoglycemia. When possible, evaluation of hypoglycemia should be carried out at the time of spontaneous occurrence of symptoms. If this is not possible then one would want to create the circumstances under which symptoms occur. In cases where symptoms occur in the post absorptive state, a 72-h fast should be performed. Likewise, if symptoms occur after a meal then a mixed meal study may be the test of choice. The causes of endogenous hyperinsulinemic hypoglycemia include insulinoma, post-bariatric hypoglycemia and noninsulinoma pancreatogenous hypoglycemia syndrome. Autoimmune hypoglycemia syndrome is clinically and biochemically similar to insulinoma but associated with high levels of insulin antibodies and plasma insulin. Other important causes of hypoglycemia include medications, non-islet cell tumors, hormonal deficiencies, critical illness and factitious hypoglycemia. We provide an overview of the pathogenesis and management of hypoglycemia in these situations.