Search Results (37)

Metanephrine (MN) and normetanephrine (NMN) are critical biomarkers for neuroendocrine tumors (pheochromocytoma and paraganglioma). Following our previous development of a molecularly imprinted solid-phase extraction (MISPE) sorbent for urine analysis, this study evaluated MISPE coupled with HILIC-MS/MS for determining metanephrines in human plasma. Unlike conventional phases, the novel polymer selectively binds analytes as in situ-generated anions via quaternary alkylammonium groups in hydroxide form, ensuring accurate extraction from just 25 µL of plasma. Validated per U.S. FDA guidelines, the assay showed good intra- and interday precision (CV < 10.8%), accuracy (bias < −10.6%) and excellent linearity (R² > 0.99) across pathological ranges (184.3–877.8 ng/L for MN; 174.8–923.0 ng/L for NMN), with low relative standard errors (<6.9%). Excellent selectivity was demonstrated in the presence of structurally close analogs (catecholamines, DOPA and its derivatives). Compared with commercial WCX, the sorbent yielded cleaner extracts, significantly reducing the phospholipid interference. Although lower limits of quantification (92.2 ng/L MN; 87.4 ng/L NMN) slightly exceeded healthy upper thresholds, the method has potential for use in specific clinical scenarios with pronounced biomarker elevations: diagnosis of pheochromocytoma/paraganglioma, monitoring post-treatment metanephrine decline, and tracking tumor-induced hypertensive crises in emergencies. This accessible protocol forms a solid foundation for advanced diagnostics. Full article

Background: Pheochromocytomas and paragangliomas (PPGLs) can be metastatic in up to 30% of cases. To assess this risk, scoring systems like PASS and GAPP were developed, yet it is unclear whether these scores correlate with somatic genetic alterations. Methods: A retrospective pilot study. Twenty patients with sporadic pheochromocytoma, stratified into high- and low-risk groups based on GAPP and PASS scores. Somatic variant burden, derived from whole-exome sequencing, and clinical variables were compared between groups. Results: Six patients (30.0%) comprised the high-risk group; all had PASS scores >4 and GAPP scores indicating moderately differentiated PPGLs. Compared with the low-risk group, the high-risk group had larger tumors (4.7 vs. 3.4 cm, p = 0.03) and non-significant association with higher diastolic blood pressure (90 vs. 79 mmHg, p = 0.09), normetanephrine (8.5 vs. 2.3 X upper limit of normal [ULN], p = 0.08), and metanephrine (22.9 vs. 9.25 X ULN, p = 0.09) levels. The high-risk group also demonstrated a higher somatic variant burden, particularly for truncating variants (32 vs. 26, p = 0.04). As a continuous variable, only the GAPP score, not PASS score, showed a significant positive correlation with variant burden, observed for both non-missense (r = 0.57, p = 0.009) and frameshift (r = 0.47, p = 0.04) variants. Conclusions: Higher pathological severity scores are associated with increased rates of severe molecular somatic variants. The stronger link between GAPP score and genetic alteration rates suggests it may better reflect the genomic complexity of sporadic PPGLs. Full article

Pheochromocytoma (PhC) and Paraganglioma (PG) are rare neuroendocrine tumors characterized by uncontrolled catecholamine secretion. Although rare, much attention is still devoted to identifying a unique biochemical signature of these diseases to reduce false positives, thus improving patient outcomes, and customizing clinical laboratory practices to available resources and specific diagnostic needs. Emerging knowledge into catecholamine metabolism has greatly improved diagnostic strategies, with current international guidelines recognizing plasma free or urinary fractionated metanephrine measurements as the recommended first-line biochemical tests. This narrative review highlights the clinical utility of measuring plasma free metanephrines compared to urinary catecholamines in the diagnosis of these conditions. Plasma free metanephrines offer superior sensitivity and specificity compared to catecholamines due to their continuous secretion, which is independent from tumor size and catecholamine fluctuations. This review also addresses preanalytical and methodological challenges, emphasizing patient preparation, sample stability and advanced analytical techniques currently available. Methodologies such as LC-MS/MS have demonstrated improved diagnostic accuracy compared to traditional immunoassays, offering enhanced analytical performance in terms of sensitivity, specificity, and reduced susceptibility to interferences. Full article

Background: Subarachnoid hemorrhage (SAH) can cause remote organ failure through complex systemic reactions. Acute respiratory failure (ARF) in the course of SAH may have a diverse etiology, including cardiogenic origin. The aim of the study was to evaluate the utility of urine metanephrine measurement in identifying the ARF phenotype in patients with SAH. Methods: A prospective single-center study was conducted between January 2022 and February 2023. The study included consecutive adult patients admitted to the Intensive Care Unit (ICU) within 24 h of SAH diagnosis and requiring mechanical ventilation due to ARF within the first 48 h of stay. Demographic and clinical data were collected. Metanephrine (MET) was determined in 24-h urine collection. The inflammatory profile was assessed by measuring serum levels of interleukin-6 (IL-6), CRP, and PCT. Cardiogenic ARF phenotype was diagnosed when concomitant elevation of hsTpI, CK-MB, and NT-proBNP was observed upon admission. Results: The study group consisted of 18 patients. The cardiogenic etiology group (n = 4) was characterized by higher MET concentrations (249 vs. 63.5 ng/mL; p = 0.007) and a lower oxygenation index (190 vs. 296 mmHg; p < 0.05) on admission. In the non-cardiogenic etiology group (n = 14), higher levels of IL-6 were found (34 vs. 8.3 pg/mL; p = 0.013). MET significantly correlated with the oxygenation index (R = −1.0; p < 0.001) on day 1 and with lactate levels on days 2 and 3 of stay (R = 1.0; p < 0.001). Baseline MET concentration accurately predicted the ARF phenotype (AUC 0.93; 95% CI 0.786–1.000, p = 0.008). Conclusions: Urine metanephrine levels show potential in differentiating the etiology of ARF and correlate with severity markers in critically ill SAH patients at an early stage. These preliminary results highlight the importance of a targeted approach to ARF diagnostics after SAH, which could support appropriate therapeutic decisions, although further validation in larger cohorts is required. Full article

Background/Objective: Pheochromocytomas and paragangliomas (PPGL) lead to marked catecholamine metabolite elevations, whereas the causes of mild increases remain unclear. We aimed to evaluate seasonal and climatic variation in plasma and urinary catecholamine metabolites in both PPGL and non-PPGL patients. Methods: We retrospectively reviewed adult patients who underwent plasma and/or 24 h urinary catecholamine metabolite testing at Ankara Bilkent City Hospital between February 2019 and May 2023. Using a big-data approach, we examined the relationship between catecholamine metabolite levels and monthly and seasonal climatic changes. Results: In non-PPGL patients, plasma metanephrine levels were significantly higher in autumn (p = 0.009) and winter (p = 0.027), and both plasma metanephrine (p < 0.001) and plasma normetanephrine (p = 0.003) showed transformed rank means in February that were elevated relative to the overall mean. Temperature, daylight duration, and humidity were the strongest predictors in the LASSO models. In contrast, catecholamine metabolite levels in the PPGL group showed no significant monthly or seasonal variation (all p > 0.05). However, when values exceeding the reference limits were examined, a significantly higher proportion of elevated plasma metanephrine measurements was observed during autumn (p = 0.005), whereas plasma normetanephrine elevations were most prominent during winter (p = 0.002). Conclusions: Catecholamine metabolite levels show notable variability in non-PPGL patients, which cannot be explained by seasonal comparisons alone. Monthly patterns and environmental factors—such as temperature, humidity, and photoperiod—should be considered when interpreting mild or borderline elevations to reduce false-positive results. In PPGL patients, seasonal variability was modest; however, plasma catecholamine metabolite testing showed higher diagnostic sensitivity during colder months. Full article

Pheochromocytomas (PHEO) are rare adrenal medullary tumours characterised by catecholamine secretion. Accurate diagnosis relies on the sensitive measurement of metanephrine (MN) and normetanephrine (NMN); however, the application of liquid chromatography–mass spectrometry (LC–MS/MS) in veterinary medicine remains limited. This study aimed to develop and analytically validate an LC–MS/MS method for the simultaneous quantification of urinary MN and NMN in dogs, establish reference intervals (RIs) for MN- and NMN-to-creatinine ratios (uMN:CR and uNMN:CR), and preliminarily assess the diagnostic utility of uNMN:CR for PHEO detection. The RIs were 2.2–78.9 nmol/mmol for uMN:CR and 4.4–77.4 nmol/mmol for uNMN:CR. Dogs with PHEO showed significantly higher uNMN:CR values compared with dogs with other adrenal masses, non-adrenal disease, or healthy controls. Using the upper RI limit as a threshold, sensitivity and specificity were 91.7% and 35.7%, respectively. Receiver operating characteristic analysis identified an optimal uNMN:CR cut-off of 203.7 nmol/mmol, yielding 78.6% sensitivity, 83.3% specificity, and an overall diagnostic accuracy of 85% (95% CI: 0.68–1.00). These findings support LC–MS/MS as a reliable approach for urinary metanephrine analysis and uNMN:CR as a valuable biochemical tool for PHEO identification in dogs. Full article

Background: Pheochromocytoma is a rare adrenal neuroendocrine tumor characterized by excessive catecholamine secretion, which can lead to significant perioperative hemodynamic instability. Despite advances in anesthetic and surgical management, intraoperative hypotension is a common complication. This study aimed to identify preoperative and intraoperative predictors of hemodynamic instability during adrenalectomy for pheochromocytoma in order to improve intraoperative management and patient safety. Methods: This retrospective study included adult patients who underwent adrenalectomy for pheochromocytoma at the University Clinical Center of Serbia between January 2022 and June 2025. Preoperative clinical and biochemical data, tumor characteristics evaluated by imaging methods (CT or MRI), surgical approach, and intraoperative hemodynamic parameters were analyzed. Intraoperative hypotension was defined as mean arterial pressure (MAP) < 60 mmHg despite adequate volume resuscitation. Univariate and multivariate logistic regression analyses were performed to identify predictors of hypotension. Results: A total of 51 adult patients were included in the analysis. Intraoperative hypotension occurred in 26 patients (51%) and was significantly associated with larger tumor size and increased intraoperative fluid requirements. Multivariate analysis identified tumor diameter ≥ 49 mm (OR 0.176, 95% CI 0.034–0.895, p = 0.036) and intraoperative crystalloid infusion ≥ 1200 mL/h (OR 0.132, 95% CI 0.030–0.574, p = 0.007) as independent predictors of intraoperative hypotension. Preoperative catecholamine levels, surgical approach, and type of alpha-blocker were not significant predictors. Conclusions: Tumor size was identified as a significant predictor of intraoperative hemodynamic instability during adrenalectomy for pheochromocytoma. Careful preoperative assessment and individualized intraoperative fluid management may help reduce the risk of hypotension and optimize perioperative outcomes. Full article

Background/Objectives: Adequate sleep has a fundamental role in human health, mainly in cognitive and physiological functions. However, the daily demands of modern society have led to a constant pursuit of better living conditions, requiring more active hours at the expense of sleeping hours. This sleep deprivation has been associated with human health deterioration, namely an increase in Diabetes Mellitus incidence. This metabolic disease is a chronic pathology that imposes a big burden on health systems and is associated with the rise in insulin resistance. In this sense, the aim of this review is to analyze the relation between sleep deprivation and insulin resistance, emphasizing the metabolic parameters and hormones that may be involved in the subjacent mechanism. Methods: A literature review of the last 10 years was performed with specific terms related to “sleep deprivation” and “insulin resistance”. Results: Overall, the studies analyzed showed a decrease in insulin sensitivity in cases of sleep deprivation, even with different study protocols. In addition, an association between sleep deprivation and increased non-esterified fatty acids was also noticeable; however, other parameters such as cortisol, metanephrines, and normetanephrines showed no consistent results among the studies. Conclusions: This review allowed us to confirm the relationship between sleep deprivation and insulin resistance; however, despite the difficulties to monitor sleep, more research is needed to understand the related mechanisms that have not yet been clarified. Full article

Plasma-free metanephrines are the most sensitive and specific biochemical markers for diagnosing catecholamine-secreting tumors, such as pheochromocytoma and paraganglioma. In this study, we developed and validated a liquid chromatography–tandem mass spectrometry method for quantifying metanephrine and normetanephrine in human plasma, using solid-phase extraction with a weak cation-exchange mechanism. Validation was performed according to the FDA Bioanalytical Method Validation Guidance and CLSI guideline C62-A. The method showed excellent linearity over concentration ranges of 0.11–13.92 nmol/L for metanephrine and 0.14–26.43 nmol/L for normetanephrine, with correlation coefficients exceeding 0.999. The accuracy, precision, and lower limit of quantification met the acceptance criteria of the study. Matrix effect evaluation revealed a process efficiency of 121% for metanephrine at the lowest concentration, slightly exceeding the acceptable range of 100 ± 15%. This was likely because of matrix-induced ion enhancement or variability in extraction efficiency. However, all other tested concentrations were within the acceptable limits. Overall, this method demonstrated high sensitivity, specificity, and reproducibility, making it suitable for routine clinical applications. Minor deviations at low concentrations do not compromise reliability; however, future optimizations, such as matrix-matched calibration, may further improve performance. Full article

Pheochromocytoma, a rare catecholamine-secreting tumor, poses significant perioperative challenges due to its potential for severe hemodynamic instability. Careful management of patients with pheochromocytoma is critical for patient safety and favorable outcomes. The diagnostic workup focuses on biochemical analysis of plasma or urinary metanephrines, followed by imaging for tumor localization and genetic testing to identify hereditary syndromes. Preoperative management emphasizes adequate alpha-adrenergic blockade followed by beta-blockade to stabilize cardiovascular function. Anesthetic planning requires meticulous attention to volume status, cardiovascular optimization, and intraoperative monitoring to mitigate the risks of hypertensive crises and hypotension. Postoperative care must account for ongoing hemodynamic and metabolic fluctuations. A multidisciplinary, protocol-driven approach is essential to improve outcomes in patients undergoing pheochromocytoma resection. This paper provides a comprehensive overview of the genetic, biochemical, clinical, and anesthetic considerations involved in the diagnosis and perioperative management of pheochromocytoma. Full article

Goats raised on pastures are seldom handled except for purposes such as weighing and providing veterinary care. Regular positive interactions with human caretakers have been reported to attenuate fear and stress responses to routine human handling; however, this has not been adequately studied in meat goats. This experiment was conducted to determine the effects of habituation to handling on behavioral, physiological, and metabolomic responses in goats when subjected to routine handling. Seventy-two male (uncastrated) Spanish goats (6 mo; BW = 25.2 ± 0.37 kg) were randomly allocated to one of two treatment (Trt) groups: (i) regularly handled by stroking the back of each goat before feeding time for 90 days (handled: H) or (ii) not subjected to handling during the same period, but all other conditions were the same (non-handled: NH). After the 90-day habituation period, the goats were subjected to an arena test in the presence of an observer. Immediately after the test, the goats were subjected to routine veterinary exams that involved blood sampling (0 min) and measuring heart rate (HR), respiratory rate (RR), rectal temperature (RT), and body weight (BW). Blood samples were also collected after the veterinary exam (20 min) to determine physiological and metabolomic responses. Data from the arena test were analyzed using a Mann–Whitney U Test, and blood physiological responses were analyzed using MIXED procedures in SAS with sampling time (Time) as a repeated measure. Unpaired t-tests showed that the increase in BW was higher in the H goats (p < 0.01) compared to the NH goats over the 90 d habituation period. The approach distance from the observer (p < 0.05) and frequency of urination (p < 0.05) were greater in the NH goats during the arena test. HR (p < 0.01) and RR (p < 0.01) were higher in the NH group compared to the H group. Plasma cortisol concentrations were higher at 20 min than at 0 min (p < 0.05), while epinephrine (p < 0.05), metanephrine, normetanephrine, phenylethylamine, and 5-methoxytryptamine concentrations were higher (p < 0.05) in the NH goats than in the H goats. A targeted metabolomics analysis showed that six of the eight affected amino acids were lower (p < 0.05), and six of the seven affected phosphatidylcholines were higher (p < 0.05) in the NH goats compared to the H goats. The results show that habituation reduces fear and stress responses to routine handling, in addition to increasing BW, which can improve the welfare of meat goats. Full article

Background: Quantifying urinary catecholamines and metanephrines is essential for the clinical screening and diagnosis of neuroendocrine tumours. HPLC with electrochemical detection (HPLC-ECD) is commonly used for this type of analysis but requires extensive sample cleanup. Simple and rapid dilute-and-shoot LC–multiple-reaction monitoring (MRM)-MS assays have been developed for quantitating these analytes in urine but have not yet been validated according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. Methods: A simple dilute-and-shoot sample preparation without derivatization was used. C18 RP-UPLC-MRM-MS and positive-ion ESI were used, usually with two transitions per analyte being monitored. Certified deuterated internal standards were used for each analyte. Results: This assay was validated according to the CLSI C62-A guidelines, including accuracy/trueness, imprecision, sensitivity, specificity, carryover, stability, and linearity. The final MRM-MS method was compared to the established HPLC-ECD clinical chemistry reference method. The run time was reduced from 25 min to 5 min. Conclusions: A simple, robust, rapid, and cost-effective LC-MRM-MS assay for measuring urinary catecholamines and metanephrines was developed and validated according to the CLSI guidelines. This validated method requires minimal sample manipulation before analysis and provides sensitivity, specificity, and improved precision. The implementation of this assay in clinical laboratories will facilitate early and accurate diagnosis. Full article

Phaeochromocytomas (PC) and sympathetic paragangliomas (PGL) are potentially malignant tumours arising from the adrenal medulla (PC) or elsewhere in the sympathetic nervous system (PGL). These tumours usually secrete catecholamines and are associated with significant morbidity and mortality, so accurate and timely diagnosis is essential. The initial diagnosis of phaeochromocytoma/paraganglioma (PPGL) is often dependent on biochemical testing. There is a range of pre-analytical, analytical and post-analytical factors influencing the analytical and diagnostic performance of biochemical tests for PPGL. Pre-analytical factors include patient preparation, sample handling and choice of test. Analytical factors include choice of methodology and the potential for analytical interference from medications and other compounds. Important factors in the post-analytical phase include provision of appropriate reference ranges, an understanding of the potential effects of various medications on metanephrine concentrations in urine and plasma and a consideration of PPGL prevalence in the patient population being tested. This article reviews these pre-analytical, analytical and post-analytical factors that must be understood in order to provide effective laboratory services for biochemical testing in the diagnosis of PPGL. Full article

Purpose: Residual adrenocortical function, RAF, has recently been demonstrated in one-third of patients with autoimmune Addison’s disease (AAD). Here, we set out to explore any influence of RAF on the levels of plasma metanephrines and any changes following stimulation with cosyntropin. Methods: We included 50 patients with verified RAF and 20 patients without RAF who served as controls upon cosyntropin stimulation testing. The patients had abstained from glucocorticoid and fludrocortisone replacement > 18 and 24 h, respectively, prior to morning blood sampling. The samples were obtained before and 30 and 60 min after cosyntropin stimulation and analyzed for serum cortisol, plasma metanephrine (MN), and normetanephrine (NMN) by liquid-chromatography tandem-mass pectrometry (LC-MS/MS). Results: Among the 70 patients with AAD, MN was detectable in 33%, 25%, and 26% at baseline, 30 min, and 60 min after cosyntropin stimulation, respectively. Patients with RAF were more likely to have detectable MN at baseline (p = 0.035) and at the time of 60 min (p = 0.048) compared to patients without RAF. There was a positive correlation between detectable MN and the level of cortisol at all time points (p = 0.02, p = 0.04, p < 0.001). No difference was noted for NMN levels, which remained within the normal reference ranges. Conclusion: Even very small amounts of endogenous cortisol production affect MN levels in patients with AAD. Full article

This experiment was conducted to determine the effects of habituation to livestock trailers on stress responses in goats transported for long periods. Intact male Spanish goats (12-month old; BW = 31.6 ± 0.34 kg; N = 168) were separated into two treatment (TRT) groups and maintained on two different paddocks. Concentrate supplement was fed to one group inside two livestock trailers (5.0 × 2.3 m each; habituated group, H), while the other group received the concentrate supplement, but not inside the trailers (non-habituated, NH). After 4 weeks of habituation period, goats were subjected to a 10-h transportation stress in four replicates (n = 21 goats/replicate/TRT). Blood samples were collected by a trained individual by jugular venipuncture into vacutainer tubes before loading (Preload), 20 min after loading (0 h), and at 2-h intervals thereafter (Time) for analysis of stress responses. There was a tendency for a TRT effect (p < 0.1) on tyramine and metanephrine concentrations. Phenylethylamine and 5-methoxytryptamine concentrations were significantly greater (p < 0.05) in the H group compared to the NH group. Both dopamine and 5-methoxytryptamine concentrations decreased (p < 0.05) with transportation time; however, TRT × Time interaction effects were not significant. Habituation to trailers may be beneficial in mood and energy stabilization in goats during long-distance transportation. Full article