Plasma Steroid Profiling Combined With Machine Learning for the Differential Diagnosis in Mild Autonomous Cortisol Secretion From Nonfunctioning Adenoma in Patients With Adrenal Incidentalomas.

OBJECTIVE: To assess the diagnostic value of combining plasma steroid profiling with machine learning (ML) in differentiating between mild autonomous cortisol secretion (MACS) and nonfunctioning adenoma (NFA) in patients with adrenal incidentalomas. METHODS: The plasma steroid profiles data in the laboratory information system were screened from January 2021 to December 2023. EXtreme Gradient Boosting was applied to establish diagnostic models using plasma 24-steroid panels and/or clinical characteristics of the subjects. The SHapley Additive exPlanation (SHAP) method was used for explaining the model. RESULTS: Seventy-six patients with MACS and 86 patients with NFA were included in the development and internal validation cohort while the external validation cohort consisted of 27 MACS and 21 NFA cases. Among 5 ML models evaluated, eXtreme Gradient Boosting demonstrated superior performance with an area under the curve of 0.77 using 24 steroid hormones. The SHAP method identified 5 steroids that exhibited optimal performance in distinguishing MACS from NFA, namely dehydroepiandrosterone, 11-deoxycortisol, 11ß-hydroxytestosterone, testosterone, and dehydroepiandrosteronesulfate. Upon incorporating clinical features into the model, the area under the curve increased to 0.88, with a sensitivity of 0.77 and specificity of 0.82. Furthermore, the results obtained through SHAP revealed that lower levels of testosterone, dehydroepiandrosterone, low-density lipoprotein cholesterol, body mass index, and adrenocorticotropic hormone along with higher level of 11-deoxycortisol significantly contributed to the identification of MACS in the model. CONCLUSIONS: We have elucidated the utilization of ML-based steroid profiling to discriminate between MACS and NFA in patients with adrenal incidentalomas. This approach holds promise for distinguishing these 2 entities through a single blood collection.

Novel Magnetic-Bead-Assisted Sequential Extraction Method for Liquid Chromatography-Mass Spectrometry (MS)/MS of Components with Diverse Properties: Gastrin Determination as a Case Study.

Sample preparation is the rate-limiting step in liquid chromatography-mass spectrometry (LC-MS)/MS-based clinical analysis when target analytes possess significantly different properties. Repeated solid-phase extraction (SPE) processes are typically required, resulting in low throughput and excessive consumption of labor, materials, and samples. In this study, we developed and validated a feasible and productive method to enrich target analytes with different properties during a single operation, while sufficiently removing matrix interferences to meet LC-MS/MS requirements. Gastrin determination was selected as the subject of this study. An automated magnetic-bead-assisted sequential extraction (MBASE) workflow was developed to simultaneously isolate nonsulfated gastrin-17 (G17ns), sulfated gastrin-17 (G17s), nonsulfated gastrin-34 (G34ns), and sulfated gastrin-34 (G34s) from human serum. It performs two different ion-exchange-based magnetic-bead extraction steps on one sample aliquot to produce one combined extract for LC-MS/MS analysis. When compared with the traditional SPE process, the MBASE workflow saves over 75% time and labor expenses as well as over 90% material cost, while providing even higher extraction efficiency. The MBASE LC-MS/MS method was validated as accurate and robust. Clinical sample test results demonstrated that the conventional chemiluminescence immunoassay method significantly under-estimated total gastrins in human serum, and the MBASE LC-MS/MS method could serve as an ideal tool to provide a comprehensive and accurate gastrin profile.

Diagnostic Accuracy of Copeptin in the Differential Diagnosis of Patients With Diabetes Insipidus: A Systematic Review and Meta-analysis.

OBJECTIVE: Accurate diagnosis of diabetes insipidus (DI) is of significant importance for correct management. We aimed to evaluate the diagnostic accuracy of copeptin level measurements in the differential diagnosis between DI and primary polydipsia (PP). METHODS: A literature search of electronic databases from January 1, 2005, to July 13, 2022, was performed. Primary studies that evaluated the diagnostic accuracy of copeptin concentration in patients with DI and PP were considered eligible. Two reviewers independently screened relevant articles and extracted data. The Quality Assessment of Diagnostic Accuracy Studies 2 tool was used to assess the quality of the included studies. The hierarchical summary receiver operating characteristic model and bivariate method were used. RESULTS: Seven studies including 422 patients with polydipsia-polyuria syndrome were included; of the 422 patients, 189 (44.79%) presented with arginine vasopressin deficiency (AVP-D, cranial DI) and 212 (50.24%) with PP. The summary estimates of the diagnostic performance of stimulated copeptin to differentiate between PP and AVP-D were 0.93 (95% CI, 0.89-0.97) for sensitivity and 0.96 (95% CI, 0.88-1.00) for specificity. Baseline copeptin level showed high performance in identifying AVP resistance (nephrogenic DI), with a pooled sensitivity of 1.00 (95% CI, 0.82-1.00) and specificity of 1.00 (95% CI, 0.98-1.00); however, it showed little value in the differentiation between PP and AVP-D. CONCLUSION: Copeptin level measurement is a useful tool for the differential diagnosis of patients with DI and PP. Stimulation before copeptin measurement is necessary in the diagnosis of AVP-D.

High Thyrotropin Levels and Risk of Mortality in the Elderly With Subclinical Hypothyroidism: A Systematic Review and Meta-analysis.

OBJECTIVE: This study aims to determine whether elevated endogenous thyrotropin levels contribute to an increased risk of adverse outcomes, such as all-cause mortality in older adults with subclinical hypothyroidism. METHODS: Eight electronic databases were searched for relevant articles from inception until March 23, 2022. Cohort studies assessing the association between thyrotropin levels and the risk of mortality among older adults aged ≥60 years with subclinical hypothyroidism were eligible. The outcomes of interest were either all-cause or cardiovascular-related mortality. Two independent researchers assessed the eligibility of the studies and collected data through a previously defined data extraction form. The Newcastle-Ottawa Scale was used to evaluate the quality of evidence, and multivariate-adjusted hazard ratios (HRs) (95% Cl) were collected as the necessary risk estimate for synthesis. Random-effects models were applied for meta-analysis. RESULTS: Overall, 13 studies involving 44 514 participants were included in this meta-analysis. There were no significant differences in the risk of all-cause mortality (pooled HR: 1.18 [95% Cl: 0.95, 1.45], I2 = 94%) and cardiovascular-related mortality (pooled HR: 1.08 [95% Cl: 0.94, 1.23], I2 = 0%) between euthyroid older adults and older adults with subclinical hypothyroidism. The results remained the same when only older adults with thyrotropin ≥10 mIU/L were assessed (pooled HR for all-cause mortality and cardiovascular-related mortality, respectively: 1.53 [95% Cl: 0.81, 2.88], I2 = 22%, 1.35 [95% Cl: 0.63, 2.86], I2 = 43%). CONCLUSION: High thyrotropin levels are not associated with increased risk for all-cause mortality as well as cardiovascular-related mortality in older adults aged ≥60 years with subclinical hypothyroidism, suggesting an unnecessity in initialing treatment.

Steroid profiling in adrenal disease.

The measurement of steroid hormones in blood and urine, which reflects steroid biosynthesis and metabolism, has been recognized as a valuable tool for identifying and distinguishing steroidogenic disorders. The application of mass spectrometry enables the reliable and simultaneous analysis of large panels of steroids, ushering in a new era for diagnosing adrenal diseases. However, the interpretation of complex hormone results necessitates the expertise and experience of skilled clinicians. In this scenario, machine learning techniques are gaining worldwide attention within healthcare fields. The clinical values of combining mass spectrometry-based steroid profiles analysis with machine learning models, also known as steroid metabolomics, have been investigated for identifying and discriminating adrenal disorders such as adrenocortical carcinomas, adrenocortical adenomas, and congenital adrenal hyperplasia. This promising approach is expected to lead to enhanced clinical decision-making in the field of adrenal diseases. This review will focus on the clinical performances of steroid profiling, which is measured using mass spectrometry and analyzed by machine learning techniques, in the realm of decision-making for adrenal diseases.

Evolution of LC-MS/MS in clinical laboratories.

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) has attracted significant attention in clinical practice owing to its numerous advantages. However, the widespread adoption of this technique is hindered by certain limitations, such as inappropriate analyte selection, low levels of automation, and a lack of specific reference intervals and quality control programs. This review comprehensively summarizes the current challenges associated with LC-MS/MS and proposes potential resolutions. The principle of utility should guide the selection of biomarkers, prioritizing their practical value over sheer quantity. To achieve full-process automation, methodological innovation is crucial for developing high-throughput equipment. Establishing reference intervals for mass spectrometry-based assays across multiple centers and diverse populations is essential for accurate result interpretation. Additionally, the development of commercial quality control materials assumes pivotal importance in ensuring assay reliability and reproducibility. Harmonization and standardization efforts should focus on the development of reference methods and materials for the clinical use of LC-MS/MS. In the future, commercial assay kits and laboratory-developed tests (LDTs) are expected to coexist in clinical laboratories, each offering distinct advantages. The collaborative efforts of diverse professionals is vital for addressing the challenges associated with the clinical application of LC-MS/MS. The anticipated advancements include simplification, increased automation, intelligence, and the standardization of LC-MS/MS, ultimately facilitating its seamless integration into clinical routines for both technicians and clinicians.

Liquid chromatography-tandem mass spectrometry in clinical laboratory protein measurement.

Proteins are essential components of human cells and tissues, and they are commonly measured in clinical laboratories using immunoassays. However, these assays have certain limitations, such as non-specificity binding, insufficient selectivity, and interference of antibodies. More sensitive, accurate, and efficient technology is required to overcome these limitations. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is a powerful analytical tool that provides high sensitivity and specificity, making it superior to traditional methods such as biochemical methods and immunoassays. While LC-MS/MS has been increasingly used for detecting small molecular analytes and steroid hormones in clinical practice recently, its application for protein or peptide analysis is still in its early stages. Established methods for quantifying proteins and peptides by LC-MS/MS are mainly focused on scientific research, and only a few proteins and peptides can be or have the potential to be detected and applied in clinical practice. Therefore, this article aims to review the clinical applications, advantages, and challenges of analyzing proteins and peptides using LC-MS/MS in clinical laboratories.

CSF and blood glial fibrillary acidic protein for the diagnosis of Alzheimer's disease: A systematic review and meta-analysis.

Recently included in the 2024 new revised diagnostic criteria of Alzheimer's disease (AD), glial fibrillary acidic protein (GFAP) has garnered significant attention. A systematic review and meta-analysis were performed to comprehensively evaluate the diagnostic, differential diagnostic, and prospective diagnostic performance of GFAP in cerebrospinal fluid (CSF) and blood for AD continuum. A literature search using common electronic databases, important websites and historical search way was performed from inception to the beginning of March 2023. The inclusion criteria was studies evaluating the diagnostic accuracy of GFAP in CSF and/or blood for the AD continuum patients, utilizing PET scans, CSF biomarkers and/or clinical criteria. The systematic review and meta-analysis were conducted referring to the Cochrane Handbook. In total, 34 articles were eventually included in the meta-analysis, 29 of which were published within the past three years. Blood GFAP exhibited good diagnostic accuracy across various AD continuum patients, and the summary area under curve for distinguishing PET positive and negative individuals, CSF biomarkers defined positive and negative individuals, clinically diagnosed AD and cognitive unimpaired controls, AD and/or mild cognitive impairment and other neurological diseases, and prospective cases and controls was 0.85[0.81-0.88], 0.77[0.73-0.81], 0.92[0.90-0.94], 0.80[0.77-0.84], and 0.79[0.75-0.82], respectively. Only several studies were recognized to evaluate the diagnostic accuracy of CSF GFAP, which was not as good as that of blood GFAP (paired mixed data: AUC = 0.86 vs. AUC = 0.77), but its accuracy remarkably increased to AUC = 0.91 when combined with other factors like sex, age, and ApoE genotype. In summary, GFAP, particularly in blood, shown good diagnostic, differential diagnostic, and prospective diagnostic accuracy for AD continuum patients, with improved accuracy when used alongside other basic indexes.

Liquid chromatography-tandem mass spectrometry in fat-soluble vitamin deficiency.

Fat-soluble vitamins, including vitamins A, D, E, and K, are essential for maintaining normal body function and metabolism. Fat-soluble vitamin deficiency may lead to bone diseases, anemia, bleeding, xerophthalmia, etc. Early detection and timely interventions are significant for preventing vitamin deficiency-related diseases. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is developing into a potent instrument for the precise detection of fat-soluble vitamins due to its high sensitivity, high specificity, and high resolution.

Preanalytical considerations in parathyroid hormone measurement.

Automated immunoassays used to evaluate parathyroid function are vulnerable to different types of interference, which can affect clinical practices. This review provides a detailed overview of the six main types of interference known to affect the measurement of parathyroid hormone (PTH): heterophilic antibodies, biotin, PTH fragments, oxidized PTH (oxPTH), phosphorylated PTH, and some preanalytical factors. Because the prevalence of some of these conditions has been reported to approach 11.7%, and the frequency of testing for parathyroid function is important, the scale of the problem might be tremendous. Potential interference in parathyroid function testing should always be suspected whenever clinical or biochemical discrepancies arise. Their identification typically relies on additional laboratory tests, including method comparison, serial dilution, blocking reagent studies, affinity adsorption, and polyethylene glycol precipitation. Moreover, some of these issues can be mitigated with the development of mass spectrometry. This review also evaluated the clinical impact of parathyroid interference on immunoassays, including misdiagnosis, inappropriate parathyroidectomy; and delay in receiving appropriate therapy. Hence, strong communication should be maintained between the clinician and laboratory to avoid such scenarios.

Establishment of a reference interval for total carbon dioxide using indirect methods in Chinese populations living in high-altitude areas: A retrospective real-world analysis.

BACKGROUND: Hypoxia leads to different concentrations of the bicarbonate buffer system in Tibetan people. Indirect methods were used to establish the reference interval (RI) for total carbon dioxide (tCO2) based on big data from the adult population of Tibet, a high-altitude area in Western China. METHODS: Anonymous tCO2 test data (n = 442,714) were collected from the People's Hospital of the Tibet Autonomous Region from January 2018, to December 2021. Multiple linear regression and variance component analyses were performed to assess the effects of sex, age, and race on tCO2 levels. Indirect methods, including Hoffmann, Bhattacharya, expectation maximization (EM), kosmic and refineR, were used to calculate the total RI and ethnicity-partitioned RI. RESULTS: A total of 230,821 real-world tCO2 test results were eligible. Sex, age, and race were significantly associated with the tCO2 levels. The total and ethnically-partitioned RIs estimated using the five indirect methods were comparable. The total RI of tCO2 was 14-24 mmol/L (calculated using Hoffmann and refineR) and 15-24 mmol/L (Bhattacharya, EM and kosmic). For Han nationality, the RIs were 14-25 mmol/L (calculated using Hoffmann and Bhattacharya), 16-23 mmol/L (EM), 15-24 mmol/L (kosmic), and 14.2-24.5 mmol/L (refineR). For the Tibetan population, the RIs were 14-24 mmol/L (calculated using Hoffmann and refineR), 15-24 mmol/L (Bhattacharya and kosmic), and 15-23 mmol/L (EM). The established RIs were significantly lower than those living at lower altitudes area (22-29 mmol/L) that was provided by the manufacturer. CONCLUSION: The tCO2 RI of the populations living on the Tibetan Plateau was significantly lower than those at the lower altitudes. The RIs established using indirect methods are suitable for clinical applications in Tibet.

Copeptin with high-sensitivity cardiac troponin to rule out non-ST-elevation myocardial infarction early on: A systematic review and meta-analysis.

High-sensitivity cardiac troponin (hs-cTn) with copeptin in rapidly ruling out non-ST-elevation myocardial infarction (NSTEMI) remains controversial. We aimed to evaluate the diagnostic accuracy of this combination compared to hs-cTn alone. A literature search of electronic databases was performed from inception to 26 March 2022. Primary studies that evaluated the diagnostic accuracy of hs-cTn with and without copeptin in patients with NSTEMI were eligible. The reference standard consisted of all available medical results, including a significant rise or fall of cTn with at least one value above the 99th percentile of the reference population. The QUality Assessment of Diagnostic Accuracy Studies (QUADAS-2) was used to assess the quality of the included studies. Thirteen studies involving 8,966 patients, 1,405 of whom were diagnosed with NSTEMI (prevalence, 15.67 %), were included. Combining copeptin with hs-cTn (99th percentile of the healthy population as the threshold) at admission improved the sensitivity from 0.89 to 0.96 (95 % confidence interval [CI] 0.84-0.93 vs 0.93-0.98); the specificity reduced from 0.79 to 0.56 (95 % CI 0.71-0.86 vs 0.51-0.60). In five studies with 6,073 participants (900 NSTEMI), the hs-cTn alone (with 'very low' or limit of detection [LoD] threshold) had higher diagnostic sensitivity than the dual-marker strategy (0.98 vs 0.96). Combining copeptin with hs-cTn (99th percentile of the population as the threshold) at admission improved sensitivity in NSTEMI identification at the expense of specificity. However, with the LoD threshold for hs-cTn, copeptin had no additional value, deterring the widespread use of copeptin if the hs-cTn assay is clinically available.

How far is the goal of applying ß-amyloid in cerebrospinal fluid for clinical diagnosis of Alzheimer's disease with standardization of measurements?

Cerebrospinal fluid (CSF) ß-amyloid (Aß) is important for early diagnosis of Alzheimer's disease (AD). However, the cohort distributions and cut-off values have large variation across different analytical assays, kits, and laboratories. In this review, we summarize the cut-off values and diagnostic performance for CSF Aß1-42 and Aß1-42/Aß1-40, and explore the important effect factors. Based on the Alzheimer's Association external quality control program (AAQC program), the peer group coefficient of variation of manual ELISA assays for CSF Aß1-42 was unsatisfied (>20%). Fully automated platforms with better performance have recently been developed, but still not widely applied. In 2020, the certified reference material (CRM) for CSF Aß1-42 was launched; however, the AAQC 2021-round results did not show effective improvements. Thus, further development and popularization of CRM for CSF Aß1-42 and Aß1-40 are urgently required. Standardizing the diagnostic procedures of AD and related status and the pre-analytical protocols of CSF samples, improving detection performance of analytical assays, and popularizing the application of fully automated platforms are also important for the establishment of uniform cut-off values. Moreover, each laboratory should verify the applicability of uniform cut-off values, and evaluate whether it is necessary to establish its own population- and assay-specific cut-off values.

Copeptin as a Diagnostic and Prognostic Biomarker in Cardiovascular Diseases.

Copeptin is the carboxyl-terminus of the arginine vasopressin (AVP) precursor peptide. The main physiological functions of AVP are fluid and osmotic balance, cardiovascular homeostasis, and regulation of endocrine stress response. Copeptin, which is released in an equimolar mode with AVP from the neurohypophysis, has emerged as a stable and simple-to-measure surrogate marker of AVP and has displayed enormous potential in clinical practice. Cardiovascular disease (CVD) is currently recognized as a primary threat to the health of the population worldwide, and thus, rapid and effective approaches to identify individuals that are at high risk of, or have already developed CVD are required. Copeptin is a diagnostic and prognostic biomarker in CVD, including the rapid rule-out of acute myocardial infarction (AMI), mortality prediction in heart failure (HF), and stroke. This review summarizes and discusses the value of copeptin in the diagnosis, discrimination, and prognosis of CVD (AMI, HF, and stroke), as well as the caveats and prospects for the application of this potential biomarker.

Review on the roles of specific cell-derived exosomes in Alzheimer's disease.

Alzheimer's disease (AD) is the sixth leading cause of death worldwide and cannot be effectively cured or prevented; thus, early diagnosis, and intervention are important. The importance of exosomes, membrane-bound extracellular vesicles produced in the endosome of eukaryotic cells, in the development, diagnosis, and treatment of AD has been recognized; however, their specific functions remain controversial and even unclear. With the development of exosome extraction, isolation, and characterization, many studies have focused on exosomes derived from different cells and body fluids. In this study, we summarized the roles of exosomes derived from different body fluids and cells, such as neuron, glial, stem, and endothelial cells, in the development, diagnosis, monitoring, and treatment of AD. We also emphasize the necessity to focus on exosomes from biological fluids and specific cells that are less invasive to target. Moreover, aside from the concentrations of classic and novel biomarkers in exosomes, the size and number of exosomes may also influence early and differential diagnosis of AD.

Copeptin in fluid disorders and stress.

Copeptin, a glycosylated peptide of 39 amino acids, is the C-terminal segment of arginine vasopressin (AVP) precursor peptide, which is consisted of two other fragments, vasopressin and neurophysin Ⅱ. The main physiological functions of AVP are fluid and osmotic balance, cardiovascular homeostasis and regulation of the endocrine stress response. Numerous studies have demonstrated that the endogenous AVP in plasma is a meaningful biomarker to guide diagnosis and therapy of diseases associated with fluids disorders and stress. However, due to its instability, short half-time life in circulation and lack of readily available AVP assays, clinical measurement of AVP is restricted. In contrast to AVP, copeptin which is released in an equimolar mode with AVP from the pituitary, has emerged as a stable and simple-to-measure surrogate marker of AVP and displays excellent potential in diagnosis, differentiation and prognosis of various diseases. This review will discuss the studies on the clinical value of copeptin in different diseases, especially in AVP-dependent fluids disorders, as well as issues and prospects of the application of this potential biomarker.