External quality assessment of hormone determinations

Spurious Serum Hormone Immunoassay Results: Causes, Recognition, Management

For over 50 years, immunoassays have been extensively used to quantitate hormones in blood, other fluids and tissues. Each assay has its own sensitivity, specificity and other analytical components. Despite the differences between commercial products, these assays provide important clinical information about hormone levels in patients. However, inaccurate results can occur because of technical issues, as well as patient-specific factors that can interfere with immunoassay hormone measurements. The latter include excessive normal blood or serum components, the presence of cross-reacting substances, extremely high levels of hormones leading to the high-dose hook effect, and interference from a variety of endogenous factors such as human antibodies that interact with the assay components or high levels of biotin in the serum from exogenous ingestion. This article briefly reviews the sources and recognition of endogenous interference, and describes methods to determine the correct serum hormone concentration.

Progress in Biosensors for the Point-of-Care Diagnosis of COVID-19

Coronavirus disease 2019 (COVID-19) is a highly virulent infection that has caused a pandemic since 2019. Early diagnosis of the disease has been recognized as one of the important approaches to minimize the pathological impact and spread of infection. Point-of-care tests proved to be substantial analytical tools, and especially lateral flow immunoassays (lateral flow tests) serve the purpose. In the last few years, biosensors have gained popularity. These are simple but highly sensitive and accurate analytical devices composed from a selective molecule such as an antibody or antigen and a sensor platform. Biosensors would be an advanced alternative to current point-of-care tests for COVID-19 diagnosis and standard laboratory methods as well. Recent discoveries related to point-of-care diagnostic tests for COVID-19, the development of biosensors for specific antibodies and specific virus parts or their genetic information are reviewed.

Hormone Immunoassay Interference: A 2021 Update

Immunoassays are powerful qualitative and quantitative analytical techniques. Since the first description of an immunoassay method in 1959, advances have been made in assay designs and analytical characteristics, opening the door for their widespread implementation in clinical laboratories. Clinical endocrinology is closely linked to laboratory medicine because hormone quantification is important for the diagnosis, treatment, and prognosis of endocrine disorders. Several interferences in immunoassays have been identified through the years; although some are no longer encountered in daily practice, cross-reaction, heterophile antibodies, biotin, and anti-analyte antibodies still cause problems. Newer interferences are also emerging with the development of new therapies. The interfering substance may be exogenous (e.g., a drug or substance absorbed by the patient) or endogenous (e.g., antibodies produced by the patient), and the bias caused by interference can be positive or negative. The consequences of interference can be deleterious when clinicians consider erroneous results to establish a diagnosis, leading to unnecessary explorations or inappropriate treatments. Clinical laboratories and manufacturers continue to investigate methods for the detection, elimination, and prevention of interferences. However, no system is completely devoid of such incidents. In this review, we focus on the analytical interferences encountered in daily practice and possible solutions for their detection or elimination.

What factors are associated with improvements in productivity in clinical laboratories in the Asia Pacific Region?

INTRODUCTION

Clinical laboratories usually have a quality management system such as ISO 15189, which provides a framework for quality and competence to perform medical testing and internal systems such as audit and nonconformance to ensure consistent processes. However, organizations need to have access to internal procedures and external competitors' performance to improve their operations. These are often seen as commercial or areas where it is difficult to agree on an acceptable goal.

METHOD

In 2019, 1158 laboratories from 17 countries/regions in the Asia Pacific Region answered the survey, including 399 Chinese sites. The survey collected information on quality, turnaround time and productivity.

RESULTS

Median productivity for laboratories in the Asia Pacific Region not including Chinese sites was 25 samples/FTE/day for small laboratories (workload: <250 samples/day), 100 for medium-sized laboratories (workload: 251-1000 samples/day) and 220 for large laboratories (workload: >1001 samples/day). The parameters associated with increased productivity in some laboratories were automation, middleware, Lean Six Sigma quality improvement activities and International Accreditation.

CONCLUSION

This survey provides evidence of an association of quality improvement activities on laboratory productivity. There are differences in the effect of these activities in Chinese and non-Chinese laboratories in the Asia Pacific Region. The survey confirmed that the implementation of automation is associated with increased median productivity in all sites. Implementation of Lean Six Sigma and International Accreditation is associated with increased productivity in large laboratories.

Integrating quality control and external quality assurance

Effective management of clinical laboratories relies upon an understanding of Quality Control and External Quality Assurance principles. These processes, when applied effectively, reduce patient risk and drive quality improvement. In this Review, we will describe the purpose of QC and EQA and their role in identifying analytical and process error. The two concepts are linked, and we will illustrate that linkage. Some EQA providers offer far more than analytical surveillance. They facilitate training and education and extend quality improvement and identify areas where there is potential for patient harm into the pre-and post-analytical phases of the total testing process.

External quality assessment program for biochemical assays of human seminal plasma: a French 6-years experience

BACKGROUND

In 1999, despite a longstanding use, the WHO manual for the examination of human semen finally proposed to assay several biochemical components of the seminal plasma for a functional exploration of the male accessory glands. At the same time, an international effort was made to standardize laboratory tests and to increase their performance through ISO 15189 accreditation. In this setting, participation to relevant external quality assessment (EQA) schemes is an essential requirement for laboratories. To fulfil this injunction, we have organized an EQA program for seminal biochemistry using presumed commutable samples. In this study, we aimed to report an overview of the French laboratory offer, the kinds of assays used, their performance as well as their likelihood of satisfying ISO15189 requirements for EQA.

RESULTS

Between 2014 and 2019, we performed seven surveys. A median of six laboratories participated to each survey giving a ratio of one laboratory per 11.2 million inhabitants. Seven biomarkers are routinely assayed but the core set shared by all laboratories comprised citrate and zinc (prostate), fructose (seminal vesicles) and α-1, 4 glucosidase (epididymis). The use of CE-IVD marked methods concerned between 0 to 75% of overall assays. According to analytical specifications, 100% of laboratories results were compliant for zinc, 75% for citrate and α-1,4 glucosidase and 67% for fructose. By combining overall data in an empirical scoring system, we identified several types of seminal biomarkers: citrate, fructose and zinc appear as good candidates for a full accreditation, α-1,4 glucosidase still presents an analytical weakness, but prostatic acid phosphatase, free L-carnitine and glycerophosphocholine cannot be accredited in the current state.

CONCLUSIONS

We organized the first French EQA program for seminal biochemistry to help local laboratories to face their legal requirement to be fully accredited by 2020. It could be improved still further but it gave us an oversight on the analytic landscape. Effective methods are available for a confident biochemical exploration of prostate and seminal vesicles. However, that of epididymis appeared unexpectedly fragile. This andrological issue should be addressed by dedicated recommendations from health authorities and scientific societies.

Can a combination of average of normals and "real time" External Quality Assurance replace Internal Quality Control?

Internal Quality Control and External Quality Assurance are separate but related processes that have developed independently in laboratory medicine over many years. They have different sample frequencies, statistical interpretations and immediacy. Both processes have evolved absorbing new understandings of the concept of laboratory error, sample material matrix and assay capability. However, we do not believe at the coalface that either process has led to much improvement in patient outcomes recently. It is the increasing reliability and automation of analytical platforms along with improved stability of reagents that has reduced systematic and random error, which in turn has minimised the risk of running less frequent IQC. We suggest that it is time to rethink the role of both these processes and unite them into a single approach using an Average of Normals model supported by more frequent External Quality Assurance samples. This new paradigm may lead to less confusion for laboratory staff and quicker responses to and identification of out of control situations.

MANAGEMENT OF ENDOCRINE DISEASE Hyperandrogenic states in women: pitfalls in laboratory diagnosis

Measuring total testosterone level is the first-line approach in assessing androgen excess in women. The main pitfalls in measuring testosterone relate to its low concentration and to the structural similarity between circulating androgens and testosterone, requiring accurate techniques with high specificity and sensitivity. These goals can be achieved by immunoassay using a specific anti-testosterone monoclonal antibody, ideally after an extraction step. Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) will be commonly used for measuring testosterone, providing optimal accuracy with a low limit of detection. Yet, the pitfalls of these two techniques are well identified and must be recognized and systematically addressed. In general, laboratories using direct testosterone immunoassay and mass spectrometry need to operate within a quality framework and be actively engaged in external quality control processes and standardization, so as to ensure appropriate interpretation irrespective of the particular laboratory. Circulating testosterone is strongly bound to sex-hormone-binding globulin (SHBG), and SHBG levels are typically low in overweight hyperandrogenic patients. Thus, low SHBG may decrease circulating testosterone to normal values, which will mask androgen excess status. One way to avoid this pitfall, awaiting direct free testosterone assays that are yet to be developed, is to measure SHBG and calculate free testosterone. A few other pitfalls will be discussed in this review, including those of adrenal androgen exploration, with the aim of helping clinicians to better handle laboratory investigation of androgen excess disorders in women.

Steroid hormone analysis in diagnosis and treatment of DSD: position paper of EU COST Action BM 1303 'DSDnet'

Disorders or differences in sex development (DSD) comprise a heterogeneous group of conditions with an atypical sex development. For optimal diagnosis, highly specialised laboratory analyses are required across European countries. Working group 3 of EU COST (European Cooperation in Science and Technology) Action BM 1303 'DSDnet' 'Harmonisation of Laboratory Assessment' has developed recommendations on laboratory assessment for DSD regarding the use of technologies and analytes to be investigated. This position paper on steroid hormone analysis in diagnosis and treatment of DSD was compiled by a group of specialists in DSD and/or hormonal analysis, either from participating European countries or international partner countries. The topics discussed comprised analytical methods (immunoassay/mass spectrometry-based methods), matrices (urine/serum/saliva) and harmonisation of laboratory tests. The following positions were agreed upon: support of the appropriate use of immunoassay- and mass spectrometry-based methods for diagnosis and monitoring of DSD. Serum/plasma and urine are established matrices for analysis. Laboratories performing analyses for DSD need to operate within a quality framework and actively engage in harmonisation processes so that results and their interpretation are the same irrespective of the laboratory they are performed in. Participation in activities of peer comparison such as sample exchange or when available subscribing to a relevant external quality assurance program should be achieved. The ultimate aim of the guidelines is the implementation of clinical standards for diagnosis and appropriate treatment of DSD to achieve the best outcome for patients, no matter where patients are investigated or managed.

Perspective and priorities for improvement of parathyroid hormone (PTH) measurement - A view from the IFCC Working Group for PTH

Parathyroid hormone (PTH) measurement in serum or plasma is a necessary tool for the exploration of calcium/phosphate disorders, and is widely used as a surrogate marker to assess skeletal and mineral disorders associated with chronic kidney disease (CKD), referred to as CKD-bone mineral disorders (CKD-MBD). CKD currently affects >10% of the adult population in the United States and represents a major health issue worldwide. Disturbances in mineral metabolism and fractures in CKD patients are associated with increased morbidity and mortality. Appropriate identification and management of CKD-MBD is therefore critical to improving clinical outcome. Recent increases in understanding of the complex pathophysiology of CKD, which involves calcium, phosphate and magnesium balance, and is also influenced by vitamin D status and fibroblast growth factor (FGF)-23 production, should facilitate such improvement. Development of evidence-based recommendations about how best to use PTH is limited by considerable method-related variation in results, of up to 5-fold, as well as by lack of clarity about which PTH metabolites these methods recognise. This makes it difficult to compare PTH results from different studies and to develop common reference intervals and/or decision levels for treatment. The implications of these method-related differences for current clinical practice are reviewed here. Work being undertaken by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) to improve the comparability of PTH measurements worldwide is also described.

Proopiomelanocortin interference in the measurement of adrenocorticotrophic hormone: a United Kingdom National External Quality Assessment Service study

OBJECTIVE

It is recognized that measurement of ACTH-precursor peptides including proopiomelanocortin (POMC) has clinical utility in identifying the aetiology of Cushing's syndrome. Recent data have also demonstrated cross-reactivity of POMC in ACTH immunoassays used in clinical laboratories. The aim of this study was to assess the cross-reactivity of POMC in the main commercial immunoassays for ACTH and to survey the awareness of laboratory professionals to this potential interference.

METHOD

To assess cross-reactivity, specimens containing ACTH and/or POMC were prepared by the UK National External Quality Assessment Service (UK NEQAS) [Edinburgh]. A separate interpretative exercise was also sent to participating laboratories.

RESULTS

Eighty-seven laboratories measured 'total' ACTH (i.e. ACTH and/or POMC) in their assays. Cross-reactivity of POMC varied from a mean of 1·6-4·7% (reflected in a large percentage increase in measured ACTH of up to 261% due to POMC cross-reactivity) depending on the manufacturer. Major differences in the clinical interpretation of test results were observed in returned responses to the interpretative exercise.

CONCLUSION

An appraisal of POMC cross-reactivity in currently available ACTH immunoassays has been achieved. Cross-reactivity was sufficient to detect ACTH precursors at concentrations that could be found in patients with ectopic ACTH syndrome. These data will assist laboratories in interpreting results when assessing the hypothalamic-pituitary-adrenal axis. Endocrinologists and laboratory professionals should be aware of the degree of cross-reactivity in ACTH immunoassay in order to minimize the risk of misinterpretation of results and/or potentially delayed treatment.

Performance characteristics of the Beckman Coulter total βhCG (5th IS) assay

BACKGROUND

Beckman Coulter recently released the first commercially available hCG reagent calibrated against the 5th International Standard (IS) for hCG (total βhCG (5th IS)). We performed a comprehensive analytical validation of this reagent.

METHODS

Precision experiments were completed using 3 concentrations of commercial quality control material. Linearity, sample stability, and analytical sensitivity were evaluated using pools of human serum. Reportable range was assessed by comparing manual dilutions to those performed by the instrument. Male and female reference intervals were established using residual serum specimens submitted for routine testing. Inter-lot variability of hCG assay reagent was assessed by analyzing serum specimens with detectable hCG using 2 different reagent lots. Inter-assay variability was established using 203 serum specimens analyzed for hCG on 6 different reagent platforms.

RESULTS

Inter-day precision showed a CV of <6.0% for all concentrations of QC material. LOB, LOD, and LOQ were determined to be 0.3, 0.4, and 0.6 U/l, respectively. The Access (5th IS) reagent has an average positive bias of approximately 20% when compared to most platforms and the previous generation Beckman hCG assay. Results were consistent between lots. Female reference intervals varied by age: <1.0 U/l (<41 y), <6.0 U/l (41-50 y), and <8.0 U/l (>50 y). Male reference intervals were <2.0 U/l.

CONCLUSIONS

The analytical performance of the total βhCG (5th IS) was established. Care should be taken to re-baseline patients needing serial monitoring and/or notify physicians when transitioning to the total βhCG (5th IS) reagent.

Pregnancy testing with hCG--future prospects

Pregnancy tests for human chorionic gonadotrophin (hCG) are used widely in hospital and home settings. Assays measuring hCG also have uses in prenatal screening and oncology. The output from three recent international workshops provides a framework for reliable measurement of hCG. Requirements for future hCG assays include use of clear descriptive nomenclature, informed selection of antibodies of well-defined epitope specificities, and design of robust methods. Tests will be precisely characterized and calibrated in SI units using six International Reference Reagents (IRR) for hCG and variants, and the Fifth International Standard for hCG 07/364, making it possible to report clinical results in molar units. These measures will help to increase patient safety by reducing the risk of erroneous or misleading hCG results.

Standardization of hormone determinations

Standardization of hormone determinations is important because it simplifies interpretation of results and facilitates the use of common reference values for different assays. Progress in standardization has been achieved through the introduction of more homogeneous hormone standards for peptide and protein hormones. However, many automated methods for determinations of steroid hormones do not provide satisfactory result. Isotope dilution-mass spectrometry (ID-MS) has been used to establish reference methods for steroid hormone determinations and is now increasingly used for routine determinations of steroids and other low molecular weight compounds. Reference methods for protein hormones based on MS are being developed and these promise to improve standardization.