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Some ELISA kits have comparable or superior diagnostic sensitivity to ANA HEp-2 and could be used as an alternative method for ANA screening, therefore allowing the immediate report of the results with fewer false negatives than ANA HEp-2. Owing to the lower specificity, ELISA-positive samples should be submitted to ANA HEp-2 for confirmation of results.

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Objective: The oral glucose tolerance test (OGTT) is used in the screening of gestational diabetes, in diagnosis of type 2 diabetes in conjunction with fasting blood glucose and glycated hemoglobin. The aim of this study was to examine the incidence and risk factors of adverse effects of OGTT in patients who underwent bariatric surgery, in addition to proposing standardization for ordering the OGTT in these patients. Subjects and methods: This study assessed the incidence of adverse effects in 128 post-bariatric surgery patients who underwent the OGTT. Descriptive and logistic regression analysis were performed, the dependent variables were defined as the presence of signs (tremor, profuse sweating, tachycardia), symptoms (nausea, diarrhea, dizziness, weakness), and hypoglycemia (blood glucose ≤ 50 mg/dL). Results: One hundred and seventeen participants (91.4%) were female; 38 (29.7%) participants were pregnant. High incidence (64.8%) of adverse effects was observed: nausea (38.4%), dizziness (30.5%), weakness (25.8%), diarrhea (23.4%), hypoglycemia (14.8%), tachycardia (14.1%), tremor (13.3%), profuse sweating (12.5%) and one case of severe hypoglycemia (24 mg/dL). The presence of signs was associated with hypoglycemia (OR = 8.1, CI 95% 2.6-25.1). The arterial hypertension persisted as a risk factor for the incidence of signs (OR = 3.6, CI 95% 1.2-11.3). Fasting glucose below 75 mg/dL increased the risk of hypoglycemia during the test (OR = 9.5, CI 95% 2.6-35.1). Conclusion: In this study, high incidence of adverse effects during the OGTT was observed in post-bariatric surgery patients. If these results are confirmed by further studies, the indication and regulation of the OGTT procedure must be reviewed for these patients. Arch Endocrinol Metab.2016;60(4):307-13

Keywords: pilot study; plasma free metanephrines; plasma total metanephrines; proficiency testing.The diagnosis of pheochromocytoma is based on the quantitation of O-methylated metabolites of catecholamines (1, 2). Several studies have reported high sensitivity of free metanephrines in plasma for assessing the presence of tumour (1). Measurement of plasma total metanephrines (plasma freeqplasma sulphoconjugated metanephrines) has also been proposed as a diagnostically sensitive assay (3). Therefore, an increasing number of laboratories have developed *Corresponding author: Dr. Eric Grouzmann, PhD, Division de Pharmacologie et Toxicologie Cliniques, University Hospital of Lausanne, Lausanne, Switzerland Phone: q41-21-3140741, Fax: q41-21-3144266, E-mail: eric.grouzmann@chuv.ch assays for free and total metanephrines using different analytical procedures including immunoassays (4, 5), high-performance liquid chromatography (HPLC) coupled to amperometric or coulometric detection (6) and liquid chromatography-tandem mass spectrometry (LC-MS) methods (7). Each laboratory is supposed to establish its own reference values and to perform quality control measurements (QCs) with each set of analyses. The internal QC samples usually are prepared by each laboratory and should include plasma samples spiked with known concentrations of both metanephrine (MN) and normetanephrine (NMN). Participation in an external quality assessment scheme (EQAS) allows direct comparisons between all laboratories that measure free and total metanephrines. In this context, the variability of the upper reference limit for free metanephrines reported in the literature is relatively large. For NMN the range varies from 0.6 to 1.4 nmol/L, and for MN it varies from 0.3 to 0.85 nmol/L (1, 2, 8). However, the upper reference limits for total metanephrines are better defined (3, 9, 10). The analytical procedure for the quantitation of metanephrines in plasma is not the only reason for this variability. The characteristics of the control population may also differ between different studies. The absence of a universal calibrator that could be used by all laboratories performing such measurements encouraged us to establish an EQA program for plasma free and total metanephrines. A similar program already exists for metanephrines and catecholamines in urine. The purpose of this letter is to present the results of a pilot study aimed at implementing a proficiency survey for all laboratories measuring plasma free and/or total metanephrines.We selected 10 centres that routinely measure free and/or total plasma metanephrines for diagnosis of pheochromocytoma. Three analytical methods were used. Immunoassays (1 participant), HPLC with electrochemical detection (ECD) (8 participants) including amperometry, coulometry, coularray and LC-MS (1 participant). All but one laboratory, which used an RIA commercial kit method, used in-house methods. Calibrators and internal quality control samples were manufactured using spiked serum pools with standard dilutions of Sigma...