Adrenal Vein Sampling for Primary Aldosteronism: Recommendations From the Australian and New Zealand Working Group.

Adrenal vein sampling (AVS) is the current recommended procedure for identifying unilateral subtypes of primary aldosteronism (PA), which are amenable to surgery with the potential for cure. AVS is a technically challenging procedure usually undertaken by interventional radiologists at tertiary centres. However, there are numerous variations in AVS protocols relating to patient preparation, sampling techniques and interpretation which may impact the success of AVS and patient care. To reduce practice variations, improve the success rates of AVS and optimise patient outcomes, we established an Australian and New Zealand AVS Working Group and developed evidence-based expert consensus recommendations for the preparation, performance and interpretation of AVS. These recommendations can be used by all healthcare professionals in a multidisciplinary team who look after the diagnosis and management of PA.

Direct-to-consumer tests advertised online in Australia and their implications for medical overuse: systematic online review and a typology of clinical utility.

OBJECTIVES: The objective of this study is to map the range and variety of direct-to-consumer (DTC) tests advertised online in Australia and analyse their potential clinical utility and implications for medical overuse. DESIGN: Systematic online search of DTC test products in Google and Google Shopping. DTC test advertisements data were collected and analysed to develop a typology of potential clinical utility of the tests at population level, assessing their potential benefits and harms using available evidence, informed by concepts of medical overuse. RESULTS: We identified 484 DTC tests (103 unique products), ranging from $A12.99 to $A1947 in cost (mean $A197.83; median $A148.50). Using our typology, we assigned the tests into one of four categories: tests with potential clinical utility (10.7%); tests with limited clinical utility (30.6%); non-evidence-based commercial 'health checks' (41.9%); and tests whose methods and/or target conditions are not recognised by the general medical community (16.7%). Of the products identified, 56% did not state that they offered pretest or post-test consultation, and 51% did not report analytical performance of the test or laboratory accreditation. CONCLUSIONS: This first-in-Australia study shows most DTC tests sold online have low potential clinical utility, with healthy consumers constituting the main target market. Harms may be caused by overdiagnosis, high rates of false positives and treatment decisions led by non-evidence-based tests, as well as financial costs of unnecessary and inappropriate testing. Regulatory mechanisms should demand a higher standard of evidence of clinical utility and efficacy for DTC tests. Better transparency and reporting of health outcomes, and the development of decision-support resources for consumers are needed.

Executive Summary: Guidelines and Recommendations for Laboratory Analysis in the Diagnosis and Management of Diabetes Mellitus.

BACKGROUND: Numerous laboratory tests are used in the diagnosis and management of patients with diabetes mellitus. The quality of the scientific evidence supporting the use of these assays varies substantially. An expert committee compiled evidence-based recommendations for laboratory analysis in patients with diabetes. The overall quality of the evidence and the strength of the recommendations were evaluated. The draft consensus recommendations were evaluated by invited reviewers and presented for public comment. Suggestions were incorporated as deemed appropriate by the authors (see Acknowledgments in the full version of the guideline). The guidelines were reviewed by the Evidence Based Laboratory Medicine Committee and the Board of Directors of the American Association of Clinical Chemistry and by the Professional Practice Committee of the American Diabetes Association. CONTENT: Diabetes can be diagnosed by demonstrating increased concentrations of glucose in venous plasma or increased hemoglobin A1c (Hb A1c) in the blood. Glycemic control is monitored by the patients measuring their own blood glucose with meters and/or with continuous interstitial glucose monitoring devices and also by laboratory analysis of Hb A1c. The potential roles of noninvasive glucose monitoring; genetic testing; and measurement of ketones, autoantibodies, urine albumin, insulin, proinsulin, and C-peptide are addressed. SUMMARY: The guidelines provide specific recommendations based on published data or derived from expert consensus. Several analytes are found to have minimal clinical value at the present time, and measurement of them is not recommended.

Executive Summary: Guidelines and Recommendations for Laboratory Analysis in the Diagnosis and Management of Diabetes Mellitus.

BACKGROUND: Numerous laboratory tests are used in the diagnosis and management of patients with diabetes mellitus. The quality of the scientific evidence supporting the use of these assays varies substantially. An expert committee compiled evidence-based recommendations for laboratory analysis in patients with diabetes. The overall quality of the evidence and the strength of the recommendations were evaluated. The draft consensus recommendations were evaluated by invited reviewers and presented for public comment. Suggestions were incorporated as deemed appropriate by the authors (see Acknowledgments in the full version of the guideline). The guidelines were reviewed by the Evidence Based Laboratory Medicine Committee and the Board of Directors of the American Association for Clinical Chemistry and by the Professional Practice Committee of the American Diabetes Association. CONTENT: Diabetes can be diagnosed by demonstrating increased concentrations of glucose in venous plasma or increased hemoglobin A1c (HbA1c) in the blood. Glycemic control is monitored by the patients measuring their own blood glucose with meters and/or with continuous interstitial glucose monitoring devices and also by laboratory analysis of HbA1c. The potential roles of noninvasive glucose monitoring; genetic testing; and measurement of ketones, autoantibodies, urine albumin, insulin, proinsulin, and C-peptide are addressed. SUMMARY: The guidelines provide specific recommendations based on published data or derived from expert consensus. Several analytes are found to have minimal clinical value at the present time, and measurement of them is not recommended.

Guidelines and Recommendations for Laboratory Analysis in the Diagnosis and Management of Diabetes Mellitus.

BACKGROUND: Numerous laboratory tests are used in the diagnosis and management of diabetes mellitus. The quality of the scientific evidence supporting the use of these assays varies substantially. APPROACH: An expert committee compiled evidence-based recommendations for laboratory analysis in screening, diagnosis, or monitoring of diabetes. The overall quality of the evidence and the strength of the recommendations were evaluated. The draft consensus recommendations were evaluated by invited reviewers and presented for public comment. Suggestions were incorporated as deemed appropriate by the authors (see Acknowledgments). The guidelines were reviewed by the Evidence Based Laboratory Medicine Committee and the Board of Directors of the American Association for Clinical Chemistry and by the Professional Practice Committee of the American Diabetes Association. CONTENT: Diabetes can be diagnosed by demonstrating increased concentrations of glucose in venous plasma or increased hemoglobin A1c (HbA1c) in the blood. Glycemic control is monitored by the people with diabetes measuring their own blood glucose with meters and/or with continuous interstitial glucose monitoring (CGM) devices and also by laboratory analysis of HbA1c. The potential roles of noninvasive glucose monitoring, genetic testing, and measurement of ketones, autoantibodies, urine albumin, insulin, proinsulin, and C-peptide are addressed. SUMMARY: The guidelines provide specific recommendations based on published data or derived from expert consensus. Several analytes are found to have minimal clinical value at the present time, and measurement of them is not recommended.

Guidelines and Recommendations for Laboratory Analysis in the Diagnosis and Management of Diabetes Mellitus.

BACKGROUND: Numerous laboratory tests are used in the diagnosis and management of diabetes mellitus. The quality of the scientific evidence supporting the use of these assays varies substantially. APPROACH: An expert committee compiled evidence-based recommendations for laboratory analysis in screening, diagnosis, or monitoring of diabetes. The overall quality of the evidence and the strength of the recommendations were evaluated. The draft consensus recommendations were evaluated by invited reviewers and presented for public comment. Suggestions were incorporated as deemed appropriate by the authors (see Acknowledgments). The guidelines were reviewed by the Evidence Based Laboratory Medicine Committee and the Board of Directors of the American Association of Clinical Chemistry and by the Professional Practice Committee of the American Diabetes Association. CONTENT: Diabetes can be diagnosed by demonstrating increased concentrations of glucose in venous plasma or increased hemoglobin A1c (Hb A1c) in the blood. Glycemic control is monitored by the people with diabetes measuring their own blood glucose with meters and/or with continuous interstitial glucose monitoring (CGM) devices and also by laboratory analysis of Hb A1c. The potential roles of noninvasive glucose monitoring, genetic testing, and measurement of ketones, autoantibodies, urine albumin, insulin, proinsulin, and C-peptide are addressed. SUMMARY: The guidelines provide specific recommendations based on published data or derived from expert consensus. Several analytes are found to have minimal clinical value at the present time, and measurement of them is not recommended.

Analytical and Non-Analytical Variation May Lead to Inappropriate Antimicrobial Dosing in Neonates: An In Silico Study.

BACKGROUND: Therapeutic drug monitoring (TDM) of aminoglycosides and vancomycin is used to prevent oto- and nephrotoxicity in neonates. Analytical and nonanalytical factors potentially influence dosing recommendations. This study aimed to determine the impact of analytical variation (imprecision and bias) and nonanalytical factors (accuracy of drug administration time, use of non-trough concentrations, biological variation, and dosing errors) on neonatal antimicrobial dosing recommendations. METHODS: Published population pharmacokinetic models and the Australasian Neonatal Medicines Formulary were used to simulate antimicrobial concentration-time profiles in a virtual neonate population. Laboratory quality assurance data were used to quantify analytical variation in antimicrobial measurement methods used in clinical practice. Guideline-informed dosing recommendations based on drug concentrations were applied to compare the impact of analytical variation and nonanalytical factors on antimicrobial dosing. RESULTS: Analytical variation caused differences in subsequent guideline-informed dosing recommendations in 9.3-12.1% (amikacin), 16.2-19.0% (tobramycin), 12.2-45.8% (gentamicin), and 9.6-19.5% (vancomycin) of neonates. For vancomycin, inaccuracies in drug administration time (45.6%), use of non-trough concentrations (44.7%), within-subject biological variation (38.2%), and dosing errors (27.5%) were predicted to result in more dosing discrepancies than analytical variation (12.5%). Using current analytical performance specifications, tolerated dosing discrepancies would be up to 14.8% (aminoglycosides) and 23.7% (vancomycin). CONCLUSIONS: Although analytical variation can influence neonatal antimicrobial dosing recommendations, nonanalytical factors are more influential. These result in substantial variation in subsequent dosing of antimicrobials, risking inadvertent under- or overexposure. Harmonization of measurement methods and improved patient management systems may reduce the impact of analytical and nonanalytical factors on neonatal antimicrobial dosing.

Simultaneous monitoring of eight human respiratory viruses including SARS-CoV-2 using liquid chromatography-tandem mass spectrometry.

Diagnosis of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection has primarily been achieved using reverse transcriptase polymerase chain reaction (RT-PCR) for acute infection, and serology for prior infection. Assay with RT-PCR provides data on presence or absence of viral RNA, with no information on virus replication competence, infectivity, or virus characterisation. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is typically not used in clinical virology, despite its potential to provide supplemental data about the presence of viral proteins and thus the potential for replication-competent, transmissible virus. Using the SARS-CoV-2 as a model virus, we developed a fast 'bottom-up' proteomics workflow for discovery of target virus peptides using 'serum-free' culture conditions, providing high coverage of viral proteins without the need for protein or peptide fractionation techniques. This workflow was then applied to Coronaviruses OC43 and 229E, Influenza A/H1N1 and H3N2, Influenza B, and Respiratory Syncytial Viruses A and B. Finally, we created an LC-MS/MS method for targeted detection of the eight-virus panel in clinical specimens, successfully detecting peptides from the SARS-CoV-2 ORF9B and nucleoprotein in RT-PCR positive samples. The method provides specific detection of respiratory viruses from clinical samples containing moderate viral loads and is an important further step to the use of LC-MS/MS in diagnosis of viral infection.

Interference by macroprolactin in assays for prolactin: will the In Vitro Diagnostics Regulation lead to a solution at last?

Cross reactivity with high molecular weight complexes of prolactin known as macroprolactin is a common cause of positive interference in assays for serum prolactin. All prolactin assays currently available are affected with 5-25% of results indicating hyperprolactinaemia falsely elevated due to macroprolactinaemia - hyperprolactinaemia due to macroprolactin with normal concentrations of bioactive monomeric prolactin. Macroprolactinaemia has no pathological significance but, if it is not recognised as the cause, the apparent hyperprolactinaemia can lead to clinical confusion, unnecessary further investigations, inappropriate treatment and waste of healthcare resources. Macroprolactinaemia cannot be distinguished from true hyperprolactinaemia on clinical grounds alone but can be detected by a simple laboratory test based on the precipitation of macroprolactin with polyethylene glycol. Laboratory screening of all cases of hyperprolactinaemia to exclude macroprolactinaemia has been advised as best practice but has not been implemented universally and reports of clinical confusion caused by macroprolactinaemia continue to appear in the literature. Information provided by manufacturers to users of assays for prolactin regarding interference by macroprolactin is absent or inadequate and does not comply with the European Union Regulation covering in vitro diagnostic medical devices (IVDR). As the IVDR is implemented notified bodies should insist that manufacturers of assays for serum prolactin comply with the regulations by informing users that macroprolactin is a source of interference which may have untoward clinical consequences and by providing an estimate of the magnitude of the interference and a means of detecting macroprolactinaemia. Laboratories should institute a policy for excluding macroprolactinaemia in all cases of hyperprolactinaemia.

Detection of Ganciclovir-Resistant Cytomegalovirus in a Prospective Cohort of Kidney Transplant Recipients Receiving Subtherapeutic Valganciclovir Prophylaxis.

Cytomegalovirus infection during antiviral prophylaxis occurs in transplant recipients despite individualized regimens based on renal function. Fifty kidney transplant recipients were assessed between 2016 and 2019 for valganciclovir dosing, ganciclovir exposure, cytomegalovirus infection, and genotypic resistance markers during the first year posttransplant. Ganciclovir plasma concentrations were measured using mass spectrometry. Population pharmacokinetics was used to determine individual ganciclovir exposure and to evaluate the ability of manufacturer dosing guidelines to meet therapeutic target daily area under the curve (AUC24) of 40 to 50 µg·h/mL. Full-length UL54 and UL97 were assessed using high-throughput sequencing in cytomegalovirus DNA-positive patient specimens. Valganciclovir doses administered to recipients with creatinine clearance of <40 mL/min were higher than specified by guidelines, and they were lower for recipients with creatinine clearance of ≥40 mL/min. The mean ganciclovir AUC24 was 33 ± 13 µg·h/mL, and 82% of subjects did not attain the therapeutic target. Pharmacokinetic simulations showed that the guidelines similarly could not attain the therapeutic target in 79% of individuals. Cytomegalovirus breakthrough occurred in 6% (3/50) of recipients, while 12% (6/50) developed late-onset infection. The mean AUC24s of recipients with (n = 3) and without (n = 47) infection were not significantly different (P = 0.528). However, one recipient with an AUC24 of 20 µg·h/mL acquired two UL97 ganciclovir resistance mutations. Current prophylaxis guidelines resulted in subtherapeutic ganciclovir exposure in several study recipients, including the emergence of resistance genotypes. IMPORTANCE This study examined the pharmacokinetics and viral genomic data from a prospective cohort of kidney transplant recipients undergoing valganciclovir prophylaxis for cytomegalovirus (CMV) prevention. We showed for the first time using high-throughput sequencing the detection of ganciclovir resistance mutations in breakthrough CMV infection during subtherapeutic plasma ganciclovir as indicated by the pharmacokinetic parameter daily area under the curve (AUC24). In addition, we found that current valganciclovir dosing guidelines for CMV prophylaxis are predicted to attain therapeutic targets in only 21% of recipients, which is consistent with previous pharmacokinetic studies. The novel findings of resistance mutations during subtherapeutic ganciclovir exposure presented here can inform future studies investigating the dynamics of drug selection pressure and the emergence of resistance mutations in vivo.

Performance of the aldosterone-to-renin ratio as a screening test for primary aldosteronism in primary care.

Primary aldosteronism (PA) is the most common and potentially curable form of secondary hypertension, affecting 5-10% of primary care patients with hypertension. Primary care physicians have an important role in initiating the screening for PA in patients with hypertension and referring to a specialist service depending on the screening test results. The currently recommended screening test for PA is the plasma aldosterone-to-renin ratio (ARR). Test results are influenced by medications so careful patient preparation is required including adjusting existing antihypertensive medications to avoid diagnostic errors. A range of laboratory method-dependent ARR thresholds are used for the screening of PA around the world. Periodic clinical audits and case reviews by clinicians and the laboratory may help refine the local thresholds. Patients with an abnormally elevated ARR should be referred to a specialist for confirmatory testing while patients with a high pre-test probability but a normal ARR could have a repeat test in view of the within-individual variability. Despite the heterogenous ARR thresholds, measuring the ARR is still more likely to detect PA than not screening at all.

Diagnostic Informatics-The Role of Digital Health in Diagnostic Stewardship and the Achievement of Excellence, Safety, and Value.

Diagnostic investigations (pathology laboratory and medical imaging) aim to: increase certainty of the presence or absence of disease by supporting the process of differential diagnosis; support clinical management; and monitor a patient's trajectory (e. g., disease progression or response to treatment). Digital health can be defined as the collection, storage, retrieval, transmission, and utilization of data, information, and knowledge to support healthcare. Digital health has become an essential component of the diagnostic process, helping to facilitate the accuracy and timeliness of information transfer and enhance the effectiveness of decision-making processes. Digital health is also important to diagnostic stewardship, which involves coordinated guidance and interventions to ensure the appropriate utilization of diagnostic tests for therapeutic decision-making. Diagnostic stewardship and informatics are thus important in efforts to establish shared decision-making. This is because they contribute to the establishment of shared information platforms (enabling patients to read, comment on, and share in decisions about their care) based on timely and meaningful communication. This paper will outline key diagnostic informatics and stewardship initiatives across three interrelated fields: (1) diagnostic error and the establishment of outcomes-based diagnostic research; (2) the safety and effectiveness of test result management and follow-up; and (3) digitally enhanced decision support systems.

The kinetic estimated glomerular filtration rate ratio predicts acute kidney injury.

AIM: Kinetic estimated Glomerular Filtration Rate (KeGFR) approximates GFR under non-steady-state conditions. We investigated whether the ratio of KeGFR difference to baseline eGFR could predict acute kidney injury (AKI) earlier than a creatinine-based algorithm that triggered an AKI electronic Alert (eAlert). METHODS: This retrospective, single-centre, proof-of-concept cohort study assessed all patients diagnosed with AKI by an automated serum creatinine-based eAlert. The kinetic eGFR, the kinetic eGFR difference from baseline and the ratio of difference to baseline was calculated in subjects with at least two serum creatinine (sCr) measurements within 72 h of AKI. RESULTS: Patients in the AKI cohort (n = 140) had a significant decline in KeGFR ratio (AKI: 17% IQR 7% to 29%, Non-AKI: 0 IQR -12% to 9%; P-value <.0001). A decrease of the ratio greater than 10% predicted AKI with a sensitivity of 66%, a specificity of 77%, a positive predictive value of 63%, and negative predictive value of 80%. The median lead time between KeGFR ratio decrease and AKI was 24 h (IQR: 19-27 h). CONCLUSIONS: KeGFR ratio is a cheap, simple method that predicted AKI 24 h before laboratory detection. KeGFR may facilitate triaging patients to increased monitoring or intervention.

Harmonization of LC-MS/MS Measurements of Plasma Free Normetanephrine, Metanephrine, and 3-Methoxytyramine.

BACKGROUND: Plasma-free normetanephrine and metanephrine (metanephrines) are the recommended biomarkers for testing of pheochromocytoma and paraganglioma (PPGL). This study evaluated the status of harmonization of liquid chromatography-tandem mass spectrometry-based measurements of plasma metanephrines and methoxytyramine and clinical interpretation of test results. METHODS: 125 plasma samples from patients tested for PPGLs were analyzed in 12 laboratories. Analytical performance was also assessed from results of a proficiency-testing program. Agreement of test results from different laboratories was assessed by Passing-Bablok regression and Bland-Altman analysis. Agreement in clinical test interpretation based on laboratory specific reference intervals was also examined. RESULTS: Comparisons of analytical test results by regression analysis revealed strong correlations for normetanephrine and metanephrine (R ≥ 0.95) with mean slopes of 1.013 (range 0.975-1.078), and 1.019 (range 0.963-1.081), and intercepts of -0.584 (-53.736 to 54.790) and -3.194 (-17.152 to 5.933), respectively. The mean bias between methods was 1.2% (-11.6% to 16.0%) for metanephrine and 0.1% (-18.0% to 9.5%) for normetanephrine. Measurements of 3-methoxytyramine revealed suboptimal agreement between laboratories with biases ranging from -32.2% to 64.0%. Interrater agreement in test interpretation was >94% for metanephrine and >84% for normetanephrine; improvements in interrater agreement were observed with use of harmonized reference intervals, including age-specific cut-offs for normetanephrine. CONCLUSIONS: Analytical methods for metanephrines are well harmonized between laboratories. However, the 16% disagreement in test interpretation for normetanephrine suggests use of suboptimal method-dependent reference intervals for clinical decision-making for this metabolite. Improved analytical methods and reference interval harmonization are particularly required for 3-methoxytyramine.

IFCC interim guidelines on rapid point-of-care antigen testing for SARS-CoV-2 detection in asymptomatic and symptomatic individuals.

With an almost unremittent progression of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections all around the world, there is a compelling need to introduce rapid, reliable, and high-throughput testing to allow appropriate clinical management and/or timely isolation of infected individuals. Although nucleic acid amplification testing (NAAT) remains the gold standard for detecting and theoretically quantifying SARS-CoV-2 mRNA in various specimen types, antigen assays may be considered a suitable alternative, under specific circumstances. Rapid antigen tests are meant to detect viral antigen proteins in biological specimens (e.g. nasal, nasopharyngeal, saliva), to indicate current SARS-CoV-2 infection. The available assay methodology includes rapid chromatographic immunoassays, used at the point-of-care, which carries some advantages and drawbacks compared to more conventional, instrumentation-based, laboratory immunoassays. Therefore, this document by the International Federation for Clinical Chemistry and Laboratory Medicine (IFCC) Taskforce on COVID-19 aims to summarize available data on the performance of currently available SARS-CoV-2 antigen rapid detection tests (Ag-RDTs), providing interim guidance on clinical indications and target populations, assay selection, and evaluation, test interpretation and limitations, as well as on pre-analytical considerations. This document is hence mainly aimed to assist laboratory and regulated health professionals in selecting, validating, and implementing regulatory approved Ag-RDTs.

Reference intervals for venous blood gas measurement in adults.

OBJECTIVES: Venous blood gas (VBG) analysis is becoming a popular alternative to arterial blood gas (ABG) analysis due to reduced risk of complications at phlebotomy and ease of draw. In lack of published data, this study aimed to establish reference intervals (RI) for correct interpretation of VBG results. METHODS: One hundred and 51 adult volunteers (101 females, 50 males, 18-70 years) were enrolled after completion of a health questionnaire. Venous blood was drawn into safePICO syringes and analysed on ABL827 blood gas analyser (Radiometer Pacific Pty. Ltd.). A non-parametric approach was used to directly establish the VBG RI which was compared to a calculated VBG RI based on a meta-analysis of differences between ABG and VBG. RESULTS: After exclusions, 134 results were used to derive VBG RI: pH 7.30-7.43, partial pressure of carbon dioxide (pCO2) 38-58 mmHg, partial pressure of oxygen (pO2) 19-65 mmHg, bicarbonate (HCO3-) 22-30 mmol/L, sodium 135-143 mmol/L, potassium 3.6-4.5 mmol/L, chloride 101-110 mmol/L, ionised calcium 1.14-1.29 mmol/L, lactate 0.4-2.2 mmol/L, base excess (BE) -1.9-4.5 mmol/L, saturated oxygen (sO2) 23-93%, carboxyhaemoglobin 0.4-1.4% and methaemoglobin 0.3-0.9%. The meta-analysis revealed differences between ABG and VBG for pH, HCO3-, pCO2 and pO2 of 0.032, -1.0 mmol/L, -4.2 and 39.9 mmHg, respectively. Using this data along with established ABG RI, calculated VBG RI of pH 7.32-7.42, HCO3- 23 - 27 mmol/L, pCO2 36-49 mmHg (female), pCO2 39-52 mmHg (male) and pO2 43-68 mmHg were formulated and compared to the VBG RI of this study. CONCLUSIONS: An adult reference interval has been established to assist interpretation of VBG results.