Differences in the actions of adrenaline and noradrenaline with regard to glucose intolerance in patients with pheochromocytoma

Main mechanisms and clinical implications of alterations in energy expenditure state among patients with pheochromocytoma and paraganglioma: A review

Pheochromocytoma and paraganglioma (PPGL) are rare neuroendocrine tumors with diverse clinical presentations. Alterations in energy expenditure state are commonly observed in patients with PPGL. However, the reported prevalence of hypermetabolism varies significantly and the underlying mechanisms and implications of this presentation have not been well elucidated. This review discusses and analyzes the factors that contribute to energy consumption. Elevated catecholamine levels in patients can significantly affect substance and energy metabolism. Additionally, changes in the activation of brown adipose tissue (BAT), inflammation, and the inherent energy demands of the tumor can contribute to increased resting energy expenditure (REE) and other energy metabolism indicators. The PPGL biomarker, chromogranin A (CgA), and its fragments also influence energy metabolism. Chronic hypermetabolic states may be detrimental to these patients, with surgical tumor removal remaining the primary therapeutic intervention. The high energy expenditure of PPGL has not received the attention it deserves, and an accurate assessment of energy metabolism is the cornerstone for an adequate understanding and treatment of the disease.

Secondary diabetes mellitus in pheochromocytomas and paragangliomas

Secondary diabetes mellitus (DM) in secretory pheochromocytomas and paragangliomas (PPGLs) is encountered in up to 50% of cases, with its presentation ranging from mild, insulin resistant forms to profound insulin deficiency states, such as diabetic ketoacidosis and hyperglycemic hyperosmolar state. PPGLs represent hypermetabolic states, in which adrenaline and noradrenaline induce insulin resistance in target tissues characterized by aerobic glycolysis, excessive lipolysis, altered adipokine expression, subclinical inflammation, as well as enhanced gluconeogenesis and glucogenolysis. These effects are mediated both directly, upon adrenergic receptor stimulation, and indirectly, via increased glucagon secretion. Impaired insulin secretion is the principal pathogenetic mechanism of secondary DM in this setting; yet, this is relevant for tumors with adrenergic phenotype, arising from direct inhibitory actions in beta pancreatic cells and incretin effect impairment. In contrast, insulin secretion might be enhanced in tumors with noradrenergic phenotype. This dimorphic effect might correspond to two distinct glycemic phenotypes, with predominant insulin resistance and insulin deficiency respectively. Secondary DM improves substantially post-surgery, with up to 80% remission rate. The fact that surgical treatment of PPGLs restores insulin sensitivity and secretion at greater extent compared to alpha and beta blockade, implies the existence of further, non-adrenergic mechanisms, possibly involving other hormonal co-secretion by these tumors. DM management in PPGLs is scarcely studied. The efficacy and safety of newer anti-diabetic medications, such as glucagon-like peptide 1 receptor agonists and sodium glucose cotransporter 2 inhibitors (SGLT2is), as well as potential disease-modifying roles of metformin and SGLT2is warrant further investigation in future studies.

Factors contributing to development and resolution of dysglycemia in patients with pheochromocytomas and catecholamine-secreting paragangliomas

BACKGROUND

Pheochromocytomas and paragangliomas (PPGLs) are a group of rare neuroendocrine tumors. Dysglycemia has been observed in patients with PPGLs in some small case series. However, there is limited information available on the factors associated with development and resolution of dysglycemia in these patients.

PATIENTS AND METHODS

The clinical data of consecutive patients admitted to our hospital with PPGLs between January 2018 and June 2020 were retrospectively analyzed. Clinical characteristics were compared between patients with and without dysglycemia. Logistic regression analysis was used to identify risk factors and receiver-operating characteristic (ROC) curve analysis was used to evaluate the diagnostic performance of the variables.

RESULTS

Among 163 patients, 58.9% had preoperative dysglycemia. Patients with dysglycemia were significantly older at diagnosis (p = 0.01) and were significantly more likely to have hypertension (p = 0.007). White blood cell counts (p = 0.016), 24-hour urinary epinephrine (24hU-E) levels (p < 0.001) and 24-hour urinary norepinethrine levels (p = 0.008) were significantly higher in patients with dysglycemia. Regression analysis showed that age (odds ratio [OR] 1.028, 95% confidence interval [CI] 1.001-1.055; p = 0.041), hypertension (OR 2.164, 95% CI 1.014-4.619; p = 0.046) and the 24hU-E concentration (OR 1.010, 95% CI, 1.001-1.019; p = 0.025) were positively associated with preoperative dysglycemia. Taking age, hypertension, and 24hU-E into account in the same model, the area under the ROC curve for prediction of preoperative dysglycemia was 0.703. The proportion of patients with dysglycemia decreased significantly after surgery (p < 0.001) and patients with preoperative dyssglycemia that resolved after surgery tended to have a larger preoperative tumor diameter (p = 0.018).

CONCLUSION

Age, hypertension, and the 24hU-E concentration are risk factors for preoperative dysglycemia. Removal of PPGLs can improve dysglycemia in most patients, and postoperative remission of dysglycemia is associated with the preoperative tumor diameter. These results are important for risk assessment and for selecting optimal therapies in patients with dysglycemia in PPGLs.KEY MESSAGESThere have been insufficient data to identify factors associated with development and resolution of dysglycemia in patients with PPGLs.Our results show that approximately half of the patients with PPGLs develop dysglycemia; age, hypertension, and the 24hU-E concentration are risk factors for preoperative dysglycemia.Removal of the PPGLs improves dysglycemia in a majority of patients, and a large preoperative tumor diameter is associated with remission of dysglycemia after surgery.

Risk factors and a predictive nomogram for hemodynamic instability during adrenalectomy for large pheochromocytomas and paragangliomas: A retrospective cohort study

OBJECTIVE

This study aimed to investigate risk factors for intraoperative hemodynamic instability (HDI) and construct a clinical model for predicting intraoperative HDI for large pheochromocytomas and paragangliomas (PPGLs) patients.

METHODS

A single-center retrospective study of the clinicopathological data of patients undergoing surgery for PPGLs larger than 5 cm in diameter was conducted. A total of 215 eligible patients were enrolled in the study. Three advanced statistical methods were used to select independent risk factors in the training cohort for constructing a nomogram for predicting intraoperative HDI. The predictive performance of the model was assessed by area under the curve (AUC), positive predictive value (PPV), negative predictive value (NPV), and calibration. Decision curve analysis (DCA) and clinical impact curves (CIC) were used to assess predictive accuracy and clinical utility. The performance of the nomogram of was further internally validated.

RESULTS

Comorbid diabetes mellitus, anemia, hypoproteinemia, 24-h urine vanillylmandelic acid and intraoperative blood transfusion (P < 0.05) were identified as independent risk factors for constructing the nomogram. In the training cohort, the AUC, PPV and NPV of the nomogram were 0.846, 91.6% and 69.2%. In the validation cohort, the AUC, PPV and NPV were 0.842, 91.8% and 63.3%. These showed good predictive power of the model. The calibration curves demonstrated an optimal consistency between the nomogram-predicted and the actual observed survival probability. DCA and CIC examination showed superior clinical relevance.

CONCLUSIONS

The nomogram can objectively and accurately predict intraoperative HDI in patients with large PPGLs, which can help in individualized pre-treatment decision-making.

Pathophysiology and Management of Glycemic Alterations before and after Surgery for Pheochromocytoma and Paraganglioma

Glycemic alterations are frequent in patients with pheochromocytoma and paraganglioma (PPGL), but the real incidence of secondary diabetes mellitus (DM) is uncertain, because prospective multicenter studies on this topic are lacking in the literature. The main pathophysiological mechanisms of glucose homeostasis alterations in PPGL, related to catecholamine hypersecretion, are impaired insulin and glucagon-like peptide type 1 (GLP-1) secretion and increased insulin resistance. Moreover, it has been reported that different pathways leading to glucose intolerance may be related to the secretory phenotype of the chromaffin tumor. Predictive factors for the development of glucose intolerance in PPGL patients are a higher age at diagnosis, the need for a higher number of anti-hypertensive drugs, and the presence of secreting neoplasms. Tumor resection is strongly related to the resolution of DM in PPGL patients, with a significant improvement of glycemic control in most cases. We can hypothesize a different personalized therapeutic approach based on the secretory phenotype. The adrenergic phenotype is more closely related to reduced insulin secretion, so insulin therapy may be required. On the other hand, the noradrenergic phenotype mainly acts by increasing insulin resistance and, therefore, insulin-sensitizing antidiabetic agents can find a greater application. Regarding GLP-1 receptor agonists, the data suggest a possible promising therapeutic effect, based on the assumption that GLP-1 secretion is impaired in patients with PPGL. The principal predictors of remission of glycemic alterations after surgery for PPGL are a lower preoperative body mass index (BMI), a larger tumor, higher preoperative catecholamine levels, and a shorter duration of the disease (under three years). Otherwise, after resection of PPGL, hypoglycemia can occur as the result of an excessive rebound of preoperative hyperinsulinemia. It is a rare, but potentially severe complication reported in a lot of case reports and a few small retrospective studies. Higher 24-h urinary metanephrine levels, longer operative times and larger tumors are predictive factors for hypoglycemia in this setting. In conclusion, alterations of carbohydrate metabolism are clinically relevant manifestations of PPGL before and after surgery, but there is the need to conduct multicenter prospective studies to obtain an adequate sample size, and to allow the creation of shared strategies for the clinical management of these potentially severe manifestations of PPGL.

Glycemic disorders in patients with pheochromocytomas and sympathetic paragangliomas

The objective of our study was to determine the prevalence of glycemic disorders (diabetes mellitus and prediabetes) in patients with pheochromocytomas and sympathetic paragangliomas (PPGLs) and identify risk factors for their development and the likelihood of their resolution after surgery. A multicentric retrospective study of patients with PPGLs submitted to surgery between 2000 and 2021 in 17 Spanish hospitals was performed. Diabetes-specific data were collected at diagnosis, in the immediate- and long-term postsurgical follow-up. A total of 229 patients with PPGLs were included (218 with pheochromocytomas and 11 with sympathetic paragangliomas). Before surgery, glycemic disorders were diagnosed in 35.4% of the patients (n = 81): 54 with diabetes and 27 with prediabetes. The variables independently associated with a higher risk of glycemic disorders were sporadic PPGL (odds ratio (OR) = 3.26 (1.14-9.36)) and hypertension (OR = 3.14 (1.09-9.01)). A significant decrease in fasting plasma glucose and HbA1c levels was observed after surgery, in the short-term and long-term follow-up (P < 0.001). After a median follow-up of 48.5 months (range 3.3-168.9), after surgery, 52% of diabetic and 68% of prediabetic patients experienced a complete resolution. Lower body mass index (BMI) (P = 0.001), lower glucose levels (P = 0.047) and shorter duration of diabetes prior to surgery (P = 0.021) were associated with a higher probability of diabetes resolution. In conclusion, glycemic disorders in patients with PPGLs are present in more than a third of them at diagnosis. Sporadic PPGLs and hypertension are risk factors for their development. More than 50% of cases experience a complete resolution of the glycemic disorder after resection of the PPGLs.

Potential Therapeutic Targeting Neurotransmitter Receptors in Diabetes

Neurotransmitters are signaling molecules secreted by neurons to coordinate communication and proper function among different sections in the central neural system (CNS) by binding with different receptors. Some neurotransmitters as well as their receptors are found in pancreatic islets and are involved in the regulation of glucose homeostasis. Neurotransmitters can act with their receptors in pancreatic islets to stimulate or inhibit the secretion of insulin (β cell), glucagon (α cell) or somatostatin (δ cell). Neurotransmitter receptors are either G-protein coupled receptors or ligand-gated channels, their effects on blood glucose are mainly decided by the number and location of them in islets. Dysfunction of neurotransmitters receptors in islets is involved in the development of β cell dysfunction and type 2 diabetes (T2D).Therapies targeting different transmitter systems have great potential in the prevention and treatment of T2D and other metabolic diseases.

Risk factors for haemodynamic instability and its prolongation during laparoscopic adrenalectomy for pheochromocytoma

OBJECTIVE

Pheochromocytoma is a rare neuroendocrine tumour that secretes catecholamines and originates in the adrenal gland. Although surgical resection is the only curative therapy for pheochromocytoma, it is associated with a risk of haemodynamic instability (HDI), such as extremely high blood pressure and/or post tumour removal hypotension and shock. We investigated the risk factors for HDI during pheochromocytoma surgery.

DESIGN AND PATIENTS

Eighty-two patients who underwent laparoscopic adrenalectomy for pheochromocytoma between July 2002 and February 2020 were examined. We excluded 3 patients with bilateral disease and 11 without detailed 24 h urinary data. We defined HDI as systolic blood pressure ≥ 200 or <80 mmHg. We investigated the risk factors for HDI during laparoscopic adrenalectomy for pheochromocytoma.

RESULTS

There were 29 males and 39 females with a median age of 50.5 years. Tumours were localised on the right adrenal gland in 28 patients and on the left in 40. The median tumour diameter was 37.5 mm and the median pneumoperitoneum time was 93.5 min. Twenty-five out of sixty-eight patients (37%) developed HDI. A multivariate analysis identified diabetes mellitus (DM; odds ratio: 3.834; 95% confidence interval: 1.062-13.83; p = .04) as an independent predictor of HDI. In terms of hormonal data, median 24 h urinary epinephrine levels (p = .04) and metanephrine levels (p = .01) were significantly higher in the HDI group. DM was also considered as a risk factor for prolonged HDI (p = .02).

CONCLUSION

Surgeons and anaesthesiologists need to be aware of the risk of HDI and its prolongation during laparoscopic adrenalectomy for pheochromocytoma for DM patients.

Correlation Between Plasma Catecholamines, Weight, and Diabetes in Pheochromocytoma and Paraganglioma

CONTEXT

Pheochromocytomas and paragangliomas (PCC/PGL) are neuroendocrine tumors with discrete catecholamine profiles that cause incompletely understood metabolic and physiologic changes.

OBJECTIVE

The objective was to evaluate relationships between plasma catecholamines, body weight, and hemoglobin A1c (HbA1c). We hypothesized that individual catecholamines would correlate negatively with weight and glucose control.

DESIGN

A retrospective cohort study was performed (1999-2020). Wilcoxon rank-sum tests compared nonparametric, continuous variables; mixed-effect linear modeling (MEM) evaluated relationships between catecholamines and weight or HbA1c. The median study duration was 54.2 months [interquartile range (IQR) 19.0-95.1].

SETTING

Tertiary academic hospital.

PATIENTS

360 patients were identified prospectively by referral to our center for management or surveillance of PCC/PGL. The median age was 59 years (IQR 45-67) and 56.4% (n = 203) were female.

MAIN OUTCOME MEASURES

The primary and secondary outcomes were weight and HbA1c, respectively.

RESULTS

On multivariable MEM, norepinephrine (P < 0.0005) negatively correlated with weight when all catecholamines and their derivatives were tried in the model, and normetanephrine (P < 0.0005) correlated when only metanephrines were included. In the surgical cohort (n = 272), normetanephrine decreased postoperatively and was inversely associated with weight (P < 0.0005). Elevated norepinephrine or normetanephrine at the study termination, indicative of metastatic and/or recurrent disease (MRD), correlated with weight loss. Norepinephrine and normetanephrine (P < 0.0005) directly correlated with HbA1c.

CONCLUSION

Plasma norepinephrine and its metabolite directly correlate with HbA1c and inversely correlate with weight in PCC/PGL. After resection, declining normetanephrine levels correlate with improving HbA1c despite an increase in patient body weight. Persistently elevated catecholamines and decreasing weight are observed in MRD.

VEGF-A/VEGF-B/VEGF-C expressions in non-hereditary, non-metastatic phaeochromocytoma

Vascular endothelial growth factor (VEGF) is important in pathogenesis of different cancers. The aim of this study is to investigate the relationships between different VEGFs and clinicopathological factors in patients with phaeochromocytomas. Twenty patients (10 men; 10 women) with non-hereditary, non-metastatic phaeochromocytomas were examined for VEGF mRNA expressions by polymerase chain reaction. The expressions were correlated with the clinical and pathological factors of the patients. In addition, mouse double minute 2 (MDM2) expression in these tumours were studied by immunohistochemistry. High expressions of VEGF-A, VEGF-B, and VEGF-C mRNA were detected in 11 (55%), 9 (45%), and 9 (45%) of the tumours respectively. High expression of VEGF-A in phaeochromocytomas was significantly correlated with the tumour size (p=0.025) but did not correlate with patients' age, gender, and tumour laterality. Besides, there was a trend of VEGF-A expression correlated with MDM2 expression (p=0.064). On the other hand, expressions of VEGF-B and VEGF-C were not significantly correlated with tumour size, patients' age, gender, tumour laterality, and MDM2 expression. In addition, high expressions of VEGF-B and VEGF-A were associated with increase of tumour size (p=0.042). Co-expression of different VEGFs did not correlate with MDM2 expression. To conclude, there is a role for VEGF-A/VEGF-B/VEGF-C in the pathogenesis of non-hereditary, non-metastatic phaeochromocytomas.

Pheochromocytoma With Adrenergic Biochemical Phenotype Shows Decreased GLP-1 Secretion and Impaired Glucose Tolerance

CONTEXT

Impaired glucose homeostasis is a common finding in pheochromocytoma (PHEO), especially with adrenergic phenotype. The possible contribution of incretin dysfunction to dysglycemia in PHEO patients has not been studied.

OBJECTIVE

To compare changes in pancreatic endocrine function and gut hormones' production during a liquid meal test before and 1 year after adrenalectomy.

METHODS

In a prospective study, we included 18 patients with PHEO (13 females) with adrenergic biochemical phenotype. A liquid meal test with predefined isocaloric enteral nutrition was performed to evaluate dynamic changes in pancreatic hormones and incretins.

RESULTS

During the meal test, insulin levels were significantly lower before adrenalectomy only in the early phase of insulin secretion, but changes in area under the curve (AUC) did not reach statistical significance (AUC = 0.07). Plasma glucagon (AUC < 0.01) and pancreatic polypeptide levels (AUC < 0.01) were suppressed in comparison with the postoperative state. Impaired response to the meal was found preoperatively for glucagon-like peptide-1 (GLP-1; AUC P < 0.05), but not glucose-dependent insulinotropic polypepide (GIP; AUC P = 0.21). No significant changes in insulin resistance indices were found, except for the homeostatic model assessment-beta index, an indicator of the function of islet β cells, which negatively correlated with plasma metanephrine (R = -0.66, P < 0.01).

CONCLUSIONS

Our study shows suppression of pancreatic α and β cell function and impaired GLP-1 secretion during a dynamic meal test in patients with PHEO, which is improved after its surgical treatment. These data demonstrate a novel and potentially significant interconnection between excessive catecholamine production and the secretion of glucoregulatory hormones.

Association between higher urinary normetanephrine and insulin resistance in a Japanese population

Since activation of the sympathetic nervous system is associated with both impaired insulin secretion and insulin resistance, or namely with diabetes, evaluation of such activation in ordinary clinical settings may be important. Therefore, we evaluated the relationships between urinary concentrations of the catecholamine metabolites, urinary normetanephrine (U-NM) and urinary metanephrine (U-M), and glucose metabolism in a general population. From 1,148 participants in the 2016 population-based Iwaki study of Japanese, enrolled were 733 individuals (gender (M/F): 320/413; age: 52.1±15.1), who were not on medication affecting serum catecholamines, not diabetic, and had complete data-set and blood glucose levels appropriate for the evaluation of insulin secretion and resistance, using homeostasis model assessment (HOMA-β and HOMA-R, respectively). Univariate linear regression analyses revealed significant correlations between both U-NM and U-M, and HOMA-β, but adjustment for multiple factors correlated with HOMA indices abolished these (β = -0.031, p = 0.499, and β = -0.055, p = 0.135, respectively). However, the correlation between U-NM and HOMA-R observed using univariate linear regression analysis (β = 0.132, p<0.001) remained significant even after these adjustments (β = 0.107, p = 0.007), whereas U-M did not correlate with HOMA-R. Furthermore, use of the optimal cut-off value of U-NM for the prediction of insulin resistance (HOMA-R >1.6) determined by ROC analysis (0.2577 mg/gCr) showed that individuals at risk had an odds ratio of 2.65 (confidence interval: 1.42–4.97) after adjustment for the same factors used above. Higher U-NM concentrations within the physiologic range are a significant risk factor for increased insulin resistance in a general Japanese population.

Glucose Intolerance on Phaeochromocytoma and Paraganglioma-The Current Understanding and Clinical Perspectives

Half of the patients with phaeochromocytoma have glucose intolerance which could be life-threatening as well as causing postoperative hypoglycemia. Glucose intolerance is due to impaired insulin secretion and/or increased insulin resistance. Impaired insulin secretion is caused by stimulating adrenergic α2 receptors of pancreatic β-cells and increased insulin resistance is caused by stimulating adrenergic α1 and β3 receptors in adipocytes, α1 and β2 receptors of pancreatic α-cells and skeletal muscle. Furthermore, different affinities to respective adrenergic receptors exist between epinephrine and norepinephrine. Clinical studies revealed patients with phaeochromocytoma had impaired insulin secretion as well as increased insulin resistance. Furthermore, excess of epinephrine could affect glucose intolerance mainly by impaired insulin secretion and excess of norepinephrine could affect glucose intolerance mainly by increased insulin resistance. Glucose intolerance on paraganglioma could be caused by increased insulin resistance mainly considering paraganglioma produces more norepinephrine than epinephrine. To conclude, the difference of actions between excess of epinephrine and norepinephrine could lead to improve understanding and management of glucose intolerance on phaeochromocytoma.

Glycemic Disturbances in Pheochromocytoma and Paraganglioma

In this review article, we aimed to analyze the available data on pheochromocytomas and paragangliomas as it pertains to their not as well-recognized association with significant glycemic abnormalities in the preoperative, perioperative, and postoperative settings as well as how they should be managed clinically. Pheochromocytomas are rare adrenal tumors that account for about 0.1% of hypertension. Paragangliomas, on the other hand, are even less common and have fewer clinical manifestations. Both types of tumors may have unusual modes of presentation which can challenge even the most experienced clinicians and are easy to overlook, resulting in post-mortem diagnosis. We wish to draw further attention to the life-threatening effects on glucose and insulin homeostasis that can occur in the form of hyperglycemic and hypoglycemic states. Hyperglycemia is a result of a glucose intolerant state created in the setting of catecholamine excess, which can present in the form of resistant diabetes, diabetic ketoacidosis (DKA), or even hyperglycemic hyperosmolar states (HHS). In many reported cases, these abnormalities resolve with resection of the tumor. However, past clinicians have also described a state of "reactive hypoglycemia" that can occur following tumor resection, further emphasizing the need for very close perioperative and postoperative monitoring. Severe hypoglycemia may also occur with inherited diseases linked to pheochromocytoma such as von Hippel-Lindau (VHL) disease as well as predominantly epinephrine-producing tumors, given some of the dramatic downstream effects of alpha and beta adrenoceptor agonization. While much of the data remains anecdotal, clinicians will benefit from the awareness of the protean manifestations of these tumors and the varied and lesser-known effects on glucose and insulin homeostasis.