Differences in the clinical and hormonal presentation of patients with familial and sporadic primary aldosteronism.

Purpose: To compare the clinical and hormonal characteristics of patients with familial hyperaldosteronism (FH) and sporadic primary aldosteronism (PA). Methods: A systematic review of the literature was performed for the identification of FH patients. The SPAIN-ALDO registry cohort of patients with no suspicion of FH was chosen as the comparator group (sporadic group). Results: A total of 360 FH (246 FH type I, 73 type II, 29 type III, and 12 type IV) cases and 830 sporadic PA patients were included. Patients with FH-I were younger than sporadic cases, and women were more commonly affected (P = 0.003). In addition, the plasma aldosterone concentration (PAC) was lower, plasma renin activity (PRA) higher, and hypokalemia (P < 0.001) less frequent than in sporadic cases. Except for a younger age (P < 0.001) and higher diastolic blood pressure (P = 0.006), the clinical and hormonal profiles of FH-II and sporadic cases were similar. FH-III had a distinct phenotype, with higher PAC and higher frequency of hypokalemia (P < 0.001), and presented 45 years before sporadic cases. Nevertheless, the clinical and hormonal phenotypes of FH-IV and sporadic cases were similar, with the former being younger and having lower serum potassium levels. Conclusion: In addition to being younger and having a family history of PA, FH-I and III share other typical characteristics. In this regard, FH-I is characterized by a low prevalence of hypokalemia and FH-III by a severe aldosterone excess causing hypokalemia in more than 85% of patients. The clinical and hormonal phenotype of type II and IV is similar to the sporadic cases.

Renin as a Biomarker to Guide Medical Treatment in Primary Aldosteronism Patients. Findings from the SPAIN-ALDO Registry.

INTRODUCTION: Primary aldosteronism (PA) is associated with several cardiometabolic comorbidities. Specific treatment by mineralocorticoid receptor antagonists (MRA) or adrenalectomy has been reported to reduce the cardiometabolic risk. However, the cardiovascular benefit could depend on plasma renin levels in patients on MRA. AIM: To compare the development of cardiovascular, renal and metabolic complications between medically treated patients with PA and those who underwent adrenalectomy, taking the renin status during MRA treatment into account. METHODS: A multicenter retrospective study (SPAIN-ALDO Register) of patients with PA treated at 35 Spanish tertiary hospitals. Patients on MRA were divided into two groups based on renin suppression (n = 90) or non-suppression (n = 70). Both groups were also compared to unilateral PA patients (n = 275) who achieved biochemical cure with adrenalectomy. RESULTS: Adrenalectomized patients were younger, had higher plasma aldosterone concentration, and lower potassium levels than MRA group. Patients on MRA had similar baseline characteristics when stratified into treatment groups with suppressed and unsuppressed renin. 97 (55.1%) of 176 patients without comorbidities at diagnosis, developed at least one comorbidity during follow-up (median 12 months vs. 12.5 months' follow-up after starting MRA and surgery, respectively). Surgery group had a lower risk of developing new cardiovascular events (HR 0.40 [95% CI 0.18-0.90]) than MRA group. Surgical treatment improved glycemic and blood pressure control, increased serum potassium levels, and required fewer antihypertensive drugs than medical treatment. However, there were no differences in the cardiometabolic profile or the incidence of new comorbidities between the groups with suppressed and unsuppressed renin levels (HR 0.95 [95% CI 0.52-1.73]). CONCLUSION: Cardiovascular, renal, and metabolic events were comparable in MRA patients with unsuppressed and suppressed renin. Effective surgical treatment of PA was associated with a decreased incidence of new cardiovascular events when compared to MRA therapy.

Risk factors for intraoperative hypertensive crisis in patients with pheochromocytomas and sympathetic paragangliomas.

PURPOSE: To identify presurgical and surgical risk factors for intraoperative hypertensive crisis in patients with pheochromocytomas and sympathetic paragangliomas (PGLs) (PPGLs). METHODS: Retrospective multicenter cohort study of patients with PPGLs from 18 tertiary hospitals. Intraoperative hypertensive crisis was defined as systolic blood pressure (SBP) greater than 200 mmHg lasting more than 1 min and postoperative hypertensive crisis as SBP greater than 180 mmHg or diastolic blood pressure (DBP) greater than 110 mmHg. RESULTS: A total of 296 surgeries were included. Alpha presurgical blockade was employed in 93.2% of the cases and beta-adrenergic in 53.4%. Hypertensive crisis occurred in 20.3% ( n  = 60) of the surgeries: intraoperative crisis in 56 and postoperative crisis in 6 cases (2 cases had both types of crises). We identified as risk factors of intraoperative hypertensive crisis, absence of presurgical glucocorticoid therapy (odds ratio [OR] 3.48; 95% confidence interval [CI] 1.19-10.12) higher presurgical SBP (OR 1.22 per each 10 mmHg, 95% CI 1.03-1.45), a larger tumor size (OR 1.09 per each 10 mm, 95% CI 1.00-1.19) and absence of oral sodium repletion (OR 2.59, 95% CI 1.25-5.35). Patients with hypertensive crisis had a higher rate of intraoperative bleeding ( P  < 0.001), of intraoperative hemodynamic instability ( P  < 0.001) and of intraoperative hypotensive episodes ( P  < 0.001) than those without hypertensive crisis. CONCLUSION: Intraoperative hypertensive crisis occurs in up to 20% of the PPGL resections. Patients not pretreated with glucocorticoid therapy before surgery, with larger tumors and higher presurgical SBP and who do not receive oral sodium repletion have a higher risk for developing hypertensive crisis during and after PPGL surgery.

Local recurrence and metastatic disease in pheochromocytomas and sympathetic paragangliomas.

Purpose: To evaluate the rate of recurrence among patients with pheochromocytomas and sympathetic paragangliomas (PGLs; together PPGLs) and to identify predictors of recurrence (local recurrence and/or metastatic disease). Methods: This retrospective multicenter study included information of 303 patients with PPGLs in follow-up in 19 Spanish tertiary hospitals. Recurrent disease was defined by the development of local recurrence and/or metastatic disease after initial complete surgical resection. Results: A total of 303 patients with PPGLs that underwent 311 resections were included (288 pheochromocytomas and 15 sympathetic PGLs). After a median follow-up of 4.8 years (range 1-19), 24 patients (7.9%) had recurrent disease (3 local recurrence, 17 metastatic disease and 4 local recurrence followed by metastatic disease). The median time from the diagnosis of the PPGL to the recurrence was of 11.2 months (range 0.5-174) and recurrent disease cases distributed uniformly during the follow-up period. The presence of a pathogenic variant in SDHB gene (hazard ratio [HR] 13.3, 95% CI 4.20-41.92), higher urinary normetanephrine levels (HR 1.02 per each increase in standard deviation, 95% CI 1.01-1.03) and a larger tumor size (HR 1.01 per each increase in mm, 95% CI 1.00-1.02) were independently associated with disease recurrence. Conclusion: The recurrence of PPGLs occurred more frequently in patients with SDHB mutations, with larger tumors and with higher urinary normetanephrine levels. Since PPGL recurrence may occur at any time after the initial PPGL diagnosis is performed, we recommend performing a strict follow-up in all patients with PPGLs, especially in those patients with a higher risk of recurrent disease.

Is adrenal venous sampling always necessary to differentiate between unilateral and bilateral primary aldosteronism? Lesson from the SPAIN-ALDO register.

PURPOSE: To evaluate whether the clinical, biochemical and radiological features of patients with primary aldosteronism (PA) can predict both main subtypes of PA. METHODS: A retrospective multicenter study of PA patients followed in 27 Spanish tertiary hospitals (SPAIN-ALDO Register). Only patients with confirmed unilateral or bilateral PA based on adrenal venous sampling (AVS) and/or postsurgical biochemical cure after adrenalectomy were included. Supervised regression techniques were used for model development. RESULTS: 328 patients [270 unilateral PA (UPA), 58 bilateral PA (BPA)] were included. The area under the curve (AUC) for aldosterone/potassium ratio and aldosterone responses following saline infusion test were 0.602 [95%CI 0.520 to 0.684] and 0.574 [95% CI 0.446-0.701], respectively, to differentiate UPA from BPA. The AUC was 0.825 [95% 0.764-0.886] when the prediction model with seven parameters - comorbidities (dyslipidemia, cerebrovascular disease, sleep apnea syndrome [SAS]), systolic blood pressure (SBP), plasma aldosterone levels (PAC), hypokalemia and unilateral adrenal nodule >1 cm and normal contralateral adrenal gland on CT/MRI - was used. In patients without comorbidities, hypokalemia, SBP > 160 mmHg, PAC > 40 ng/dL, and unilateral adrenal lesions were associated with a likelihood of having a UPA of 98.5%. The chance of BPA was higher in individuals with comorbidities, SBP < 140 mmHg, normokalemia, low PAC levels, and no adrenal tumors on the CT/MRI (91.5%). CONCLUSION: A combination of high PAC, SBP > 160 mmHg, low serum potassium, a unilateral adrenal nodule>1 cm and no comorbidities could predict a UPA with a 98.5% accuracy.

Autonomous cortisol secretion in patients with primary aldosteronism: prevalence and implications on cardiometabolic profile and on surgical outcomes.

Purpose: The aim of this study was to evaluate the prevalence of autonomous cortisol secretion (ACS) in patients with primary aldosteronism (PA) and its implications on cardiometabolic and surgical outcomes. Methods: This is a retrospective multicenter study of PA patients who underwent 1 mg dexamethasone-suppression test (DST) during diagnostic workup in 21 Spanish tertiary hospitals. ACS was defined as a cortisol post-DST >1.8 µg/dL (confirmed ACS if >5 µg/dL and possible ACS if 1.8-5 µg/dL) in the absence of specific clinical features of hypercortisolism. The cardiometabolic profile was compared with a control group with ACS without PA (ACS group) matched for age and DST levels. Results: The prevalence of ACS in the global cohort of patients with PA (n = 176) was 29% (ACS-PA; n = 51). Ten patients had confirmed ACS and 41 possible ACS. The cardiometabolic profile of ACS-PA and PA-only patients was similar, except for older age and larger tumor size of the adrenal lesion in the ACS-PA group. When comparing the ACS-PA group (n = 51) and the ACS group (n = 78), the prevalence of hypertension (OR 7.7 (2.64-22.32)) and cardiovascular events (OR 5.0 (2.29-11.07)) was higher in ACS-PA patients than in ACS patients. The coexistence of ACS in patients with PA did not affect the surgical outcomes, the proportion of biochemical cure and clinical cure being similar between ACS-PA and PA-only groups. Conclusion: Co-secretion of cortisol and aldosterone affects almost one-third of patients with PA. Its occurrence is more frequent in patients with larger tumors and advanced age. However, the cardiometabolic and surgical outcomes of patients with ACS-PA and PA-only are similar.

An Integrated CT and MRI Imaging Model to Differentiate between Adrenal Adenomas and Pheochromocytomas.

PURPOSE: to perform an external validation of our predictive model to rule out pheochromocytoma (PHEO) based on unenhanced CT in a cohort of patients with PHEOs and adenomas who underwent adrenalectomy. METHODS: The predictive model was previously developed in a retrospective cohort of 1131 patients presenting with adrenal lesions. In the present study, we performed an external validation of the model in another cohort of 214 patients with available histopathological results. RESULTS: For the external validation, 115 patients with PHEOs and 99 with adenomas were included. Our previously described predictive model combining the variables of high lipid content and tumor size in unenhanced CT (AUC-ROC: 0.961) had a lower diagnostic accuracy in our current study population for the prediction of PHEO (AUC: 0.750). However, when we excluded atypical adenomas (with Hounsfield units (HU) > 10, n = 39), the diagnostic accuracy increased to 87.4%. In addition, in the whole cohort (including atypical adenomas), when MRI information was included in the model, the diagnostic accuracy increased to up to 85% when the variables tumor size, high lipid content in an unenhanced CT scan, and hyperintensity in the T2 sequence in MRI were included. The probability of PHEO was <0.3% for adrenal lesions <20 mm with >10 HU and without hyperintensity in T2. CONCLUSION: Our study confirms that our predictive model combining tumor size and lipid content has high reliability for the prediction of PHEO when atypical adrenal lesions are excluded. However, for atypical adrenal lesions with >10 HU in an unenhanced CT scan, MRI information is necessary for a proper exclusion of the PHEO diagnosis.

Effect of Obesity on Clinical Characteristics of Primary Aldosteronism Patients at Diagnosis and Postsurgical Response.

CONTEXT: Patients with obesity have an overactivated renin-angiotensin-aldosterone system (RAAS) that is associated with essential hypertension. However, the influence of obesity in primary aldosteronism (PA) is unknown. OBJECTIVE: We analyzed the effect of obesity on the characteristics of PA, and the association between obesity and RAAS components. METHODS: A retrospective study was conducted of the Spanish PA Registry (SPAIN-ALDO Registry), which included patients with PA seen at 20 tertiary centers between 2018 and 2022. Differences between patients with and without obesity were analyzed. RESULTS: A total of 415 patients were included; 189 (45.5%) with obesity. Median age was 55 years (range, 47.3-65.2 years) and 240 (58.4%) were male. Compared to those without obesity, patients with obesity had higher rates of diabetes mellitus, chronic kidney disease, obstructive apnea syndrome, left ventricular hypertrophy, prior cardiovascular events, higher means of systolic blood pressure, and required more antihypertensive drugs. Patients with PA and obesity also had higher values of serum glucose, glycated hemoglobin A1c, creatinine, uric acid, and triglycerides, and lower levels of high-density lipoprotein cholesterol. Levels of blood aldosterone (PAC) and renin were similar between patients with and without obesity. Body mass index was not correlated with PAC nor renin. The rates of adrenal lesions on imaging studies, as well as the rates of unilateral disease assessed by adrenal vein sampling or I-6ß-iodomethyl-19-norcholesterol scintigraphy, were similar between groups. CONCLUSION: Obesity in PA patients involves a worse cardiometabolic profile, and need for more antihypertensive drugs but similar PAC and renin levels, and rates of adrenal lesions and lateral disease than patients without obesity. However, obesity implicates a lower rate of hypertension cure after adrenalectomy.

Genetic Study in Pheochromocytoma: Is It Possible to Stratify the Risk of Hereditary Pheochromocytoma?

INTRODUCTION: It is estimated that 30-40% of patients with apparently sporadic pheochromocytomas (PHEOs) have an inherited predisposition syndrome. The aim of our study was to develop a predictive model of hereditary PHEO based on the clinical, hormonal, and radiological features present at the diagnosis of patients with PHEOs. METHODS: A retrospective multicenter cohort study of patients with PHEOs with available genetic study from 18 tertiary hospitals. Clinical, biochemical, and radiological features were used to build a multivariate logistic regression model. The estimation of all possible equations was used to select the model with the best diagnostic accuracy (lower Akaike index). RESULTS: A total of 245 patients were included: 169 (69.0%) patients with sporadic PHEOs and 76 (31%) with hereditary PHEOs. The parsimonious predictive model with the highest diagnostic accuracy for the prediction of hereditary PHEO combined the variables age, non-cardiovascular disease, urinary norepinephrine levels, and tumor size. The area under the ROC curve of this model was 0.800 (0.705-0.887). Based on the predictive model, the probability of hereditary PHEO in patients older than 60 years with cardiovascular disease, high levels of urinary norepinephrine and unilateral PHEOs >60 mm was <2%. And if the age was above 80 years, lower than 1%. The probability of sporadic PHEO linearly increased with age (MH Test for linear Trend: χ2 (1) = 30.05; p < 0.001). CONCLUSION: In certain populations such as old patients with cardiovascular disease, with high levels of urinary norepinephrine and large tumors in which the probability of hereditary PHEO is very low, genetic testing could be avoided in the absence of specific suspicion.

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.

Predictive model of hypertension resolution after adrenalectomy in primary aldosteronism: the SPAIN-ALDO score.

PURPOSE: To develop a predictive model of hypertension resolution after adrenalectomy in patients with primary aldosteronism (PA), based on their presurgical characteristics. METHODS: A retrospective multicenter study of PA patients in follow-up in 20 Spanish tertiary hospitals between 2018 and 2021 was performed (SPAIN-ALDO Register). Clinical response postadrenalectomy was classified according to the primary aldosteronism surgical outcome (PASO) consensus criteria. The predictive model was developed using a multivariate logistic regression model with the estimation of all possible equations. RESULTS: A total of 146 patients (54.8% females; mean age of 51.5 ± 10.9 years) with PA who underwent unilateral adrenalectomy were included. After a mean follow-up of 29.1 ±â€Š30.43 months after surgery, hypertension cure was obtained in 37.7% ( n  = 55) of the patients. The predictive model with the highest diagnostic accuracy to predict hypertension cure combined the variables female sex, use of two or fewer antihypertensive medications, hypertension grade 1, without type 2 diabetes and nonobesity. The area under the receiver operating characteristic curve of this model was 0.841 [0.769-0.914]. Based on this model, the group of patients with a higher probability of cure (80.4%) were those without type 2 diabetes, BMI <30 kg/m 2 , female sex, hypertension grade 1 and who use two or fewer antihypertensives. Our predictive model offered a slightly higher diagnostic accuracy than Wachtel's (area under the curve [AUC]: 0.809), Utsumi's (AUC: 0.804) and Zarnegar's (AUC: 0.796) models and was similar than the Burello's (AUC: 0.833) model. CONCLUSION: Female sex, use of two or fewer antihypertensive medications, hypertension grade 1, no type 2 diabetes and nonobesity may predict hypertension cure after adrenalectomy in patients with PA. Our score provides a potential tool to guide preoperative patient counseling.

Adrenal venous sampling in primary aldosteronism: Experience of a Spanish multicentric study (Results from the SPAIN-ALDO Register).

OBJECTIVE: The aim of this study was to evaluate the rate of adrenal venous sampling (AVS) performance in patients with primary aldosteronism (PA), the main reasons for its non-performance, and the success and complications rate of this procedure in Spain. Moreover, the concordance between CT/MRI and AVS for PA subtyping was evaluated. METHODS: A retrospective multicenter study of PA patient follow-up in 20 Spanish tertiary hospitals between 2018-2021 was performed (SPAIN-ALDO Register). RESULTS: Of the 440 patients with PA included in the study, 153 underwent AVS (34.8%). The main reasons for not performing AVS were: patient rejection to the procedure, low catheterization rate in the center and unilateral disease based on CT/MRI. The overall success rate was 44.4% (the left adrenal vein was properly canulated in 77.8% and the right adrenal vein in 48.4%). Only 3 patients experienced minor complications. In the 45 patients with unilateral disease according to AVS, CT/MRI indicated bilateral disease or normal adrenal glands in 17. In the 23 patients with bilateral disease, CT/MRI indicated unilateral disease in 14. However, no significant differences were observed in biochemical response (P = 0.051) and hypertension resolution (P = 0.150) between patients who underwent surgery based on CT/MRI results and those who underwent surgery based on AVS results. CONCLUSION: In our setting, AVS is still an underused technique in patients with PA. The low experience and success rate in AVS partially justify these results. More training for providers and patients needs to be done to include appropriate well performed AVS in the diagnosis algorithm of PA.

Differences in the presentation and evolution of primary aldosteronism in elderly (≥65 years) and young patients (<65 years).

Objective: To compare the presentation and evolution of primary aldosteronism (PA) in the elderly (≥65 years) and young patients (<65 years). Methods: A retrospective multicenter study was performed in 20 Spanish hospitals of PA patients in follow-up between 2018 and 2021. Results: Three hundred fifty-two patients with PA <65 years and 88 patients ≥65 years were included. Older PA patients had a two-fold higher prevalence of type 2 diabetes, dyslipidemia, and cerebrovascular disease, but these differences disappeared after adjusting for hypertension duration. At diagnosis, diastolic blood pressure was lower than in young patients (83.3 ± 11.54 vs 91.6 ± 14.46 mmHg, P < 0.0001). No differences in the rate of overall correct cannulation (56.5% vs 42.3%, P = 0.206) or the diagnosis of unilaterality (76.9% vs 62.5%, P = 0.325) in the adrenal venous sampling (AVS) was observed between the elderly and young groups. However, there was a lower proportion of PA patients who underwent adrenalectomy in the elderly group than in the younger group (22.7% (n = 20) vs 37.5% (n = 132), P = 0.009). Nevertheless, no differences in the rate of postsurgical biochemical (100% (n = 14) vs 92.8% (n = 90), P = 0.299) and hypertension cure (38.6% (n = 51) vs 25.0% (n = 5), P = 0.239) were observed between both groups. Conclusion: Older patients with PA have a worse cardiometabolic profile than young patients with PA that it is related to a longer duration of hypertension. However, the results of the AVS, and adrenalectomy are similar in both groups. Therefore, the management of elderly patients with PA should be based not only on age, but rather on the overall medical, physical, social, and mental characteristics of the patients.

Doege-Potter syndrome in a facial solitary fibrous tumor: Diagnose and clinical management discussion.

Doege-Potter syndrome is a rare hypoglycemic paraneoplastic disorder. This case describes that severe and symptomatic hypoglycemia can occasionally be due to a rare malignant neoplasm, and the differential diagnosis of malignancy should not be overlooked in this setting.

Assessing the quality of the evidence underlying recommendations in type 2 diabetes' commonly used clinical practice guidelines.

AIM: In a world of data overload, clinical practice recommendations are needed to help practitioners and patients to take evidence-based decisions. However, in the field of type 2 diabetes mellitus (T2DM) recommendations on glycemic goals and treatment choice are controversial in spite of being supported by a common body of evidence. We hypothesize that internal and external validity of this body of evidence might not be as sound as expected. The aim of the current study is to appraise the studies supporting recommendations developed by influential medical societies dealing with glycemic goals and the choice of pharmacological treatment in adults with T2DM. METHODS: Clinical practice recommendations and their references were extracted out of eight documents developed by influential scientific societies between 2016 and 2019. Internal and external validity of each study was then appraised with standard tools and in duplicate. RESULTS: A total of 114 recommendations and their underlying 233 citations were extracted. Out of these 233 citations 81 (35%) corresponded to randomized controlled trials (RCT) and 45 (20%) to systematic reviews. After systematical appraisal only four RCT (5%) and eight systematic reviews (17%) were considered to be unflawed. Indirectness (lack of generalizability) was the most common caveat identified in RCTs. Out of the 114 recommendations analyzed (32 dealing with glycemic goals and 82 with treatment choice), only 21 (18.4%) were supported by at least one high-quality study. CONCLUSION: Only one in five recommendations regarding glycemic goals or pharmacological treatment choice in T2DM is based on at least one high-quality study. Clinical practice recommendations dealing with areas of uncertainty should be formulated more transparently to enable real evidence-based decisions.

Coronavirus disease 2019 (COVID-19) and obesity. Impact of obesity and its main comorbidities in the evolution of the disease.

The COVID-19 pandemic is posing a great challenge worldwide. Its rapid progression has caused thousands of deaths worldwide. Although multiple aspects remain to be clarified, some risk factors associated with a worse prognosis have been identified. These include obesity and some of its main complications, such as diabetes and high blood pressure. Furthermore, although the possible long-term complications and psychological effects that may appear in survivors of COVID-19 are not well known yet, there is a concern that those complications may be greater in obese patients. In this manuscript, we review some of the data published so far and the main points that remain to be elucidated are emphasized.