Standardization of hormone determinations

Recent advances in liquid chromatography-tandem mass spectrometry for the detection of thyroid hormones and thyroglobulin in clinical samples: A review

Thyroid hormones (THs), including triiodothyronine (T3), thyroxine (T4), and their metabolites, are essential for regulating development, growth, and energy metabolism. Thyroglobulin (Tg) produced by thyroid follicular cells acts as an essential substrate for TH synthesis. The combination of THs with Tg is a widely used serological laboratory test for thyroid function assessment. Early detection and timely intervention are significant for preventing and managing thyroid disease. In recent years, liquid chromatography-tandem mass spectrometry (LC-MS/MS) has emerged as a powerful tool for the precise detection of small molecular analytes and steroid hormones in clinical practice as a result of its high sensitivity and specificity. While LC-MS/MS has been increasingly used for detecting THs and Tg recently, its application in clinical practice is still in its early stages. Recent advances in the assessment of thyroid metabolism using LC-MS/MS in clinical samples published during 2004-2023 were reviewed, with a special focus on the use of this technique for quantifying molecules involved in thyroid diseases.

IL-1, IL-6, TNF-α, and MIF in relative adrenal insufficiency in septic shock: a piglet model

BACKGROUND Inflammatory mediators released during septic shock are involved in the mechanism of adrenal insufficiency. This study investigated the role of interleukin (IL)-6, IL-1, tumor necrosis factor (TNF)-α, and macrophage migration inhibitory factor (MIF) in septic shock with relative adrenal insufficiency (RAI). METHODS We conducted a 6-month experimental study in 20 piglets. Following endotoxin administration, their hemodynamics were monitored and blood samples were drawn to test the levels of cytokines IL-1, IL-6, TNF-α, and MIF every 15 min until septic shock onset as well as during a corticotropin stimulation test. Septic shock was managed by administering fluid resuscitation, inotropic drugs, and hydrocortisone. At the end of the study, the piglet models were classified as either RAI or non-RAI. Immunohistochemistry staining was performed on the hypothalamus of the RAI group. RESULTS The level of IL-6 at 45 min was higher in the RAI group than the non-RAI group (p = 0.008), and that of IL-1 was similar in the two groups during septic shock. The RAI group had higher TNF-α levels at 15 min (p = 0.002) and at 30 min (p = 0.007) than the non-RAI group, and the MIF level during septic shock was higher in the RAI group (p = 0.003) than the non-RAI group. CONCLUSIONS Cytokine-induced inflammatory process of adrenal gland reflected in TNF-α level in 15 min and 30 min, IL-6 in 45 min, and MIF in septic shock condition but not in IL-1.

A Brief History of Modern Endocrinology and Definitions of a True Hormone

Background and Objective:

An overview of the history of endocrinology indicates that definitions of some initially developed concepts, including the term ‘hormone’ have been changed over time. This review provides a historical overview of current definitions of ‘hormone’ and the criteria of a true hormone. In addition, a brief history of hormone-related concepts and their transformation over time are discussed.

Results:

Classically, a hormone is a chemical substance secreted into the bloodstream and acts on distant tissues, usually in a regulatory fashion. Several newly discovered bioregulators and chemical signaling molecules are far from the classical definition of a true hormone and could not fulfill many relevant criteria. Major developments in the field of endocrinology accompanied by the complex terminology, currently used to describe hormonal actions of chemical messengers, underscore the need of the revision of such classical concepts.

Conclusion:

Complex terminology currently used to describe different hormonal actions of chemical messengers, suggests that it is time to conceptualize the term hormone and revise its classical definition.

Cross-method comparison of serum androstenedione measurement with respect to the validation of a new fully automated chemiluminescence immunoassay

OBJECTIVES

Androstenedione is an androgen produced as an intermediate product of the biosynthesis of testosterone and estradiol in testicles, ovaries and also in the adrenal cortex. Measurement is used for diagnosing and differentiating hirsutism and virilisation, enzyme deficiencies of the steroid hormone biosynthesis, and in suspicion of androgen-producing tumors.

METHODS

Specimens included de-identified residual serum specimens submitted for routine testing and banked adult and pediatric sera. Samples were measured with tandem mass spectrometry, two automated immunoassays, the newly developed DiaSorin LIAISON androstenedione assay, the Immulite assay, and a radioimmunoassay (Beckman Coulter) according to manufacturer's protocols. All methods were correlated, and the analytical sensitivity, linearity and imprecision of each assay determined. Diagnostic accuracy with respect to detection of PCOS in women was evaluated by verifying the respective reference ranges of the different assays and receiver operating characteristic (ROC) curve analysis.

RESULTS

Due to the methodology, LC-MS/MS demonstrated the highest analytical specificity, good performance and excellent diagnostic accuracy. The best agreement was found with the LIAISON chemiluminescent immunoassay method. Due to its lower analytical sensitivity, the measured values in children were often outside the measuring range. Although, the coefficient of correlation between LC-MS/MS and the Beckman Coulter radioimmunoassay was lower, the assay demonstrated the best analytical sensitivity and a similar diagnostic accuracy in adults. The Immulite androstenedione chemiluminescent immunoassay showed the poorest performance and was not interchangeable with the other assays.

CONCLUSIONS

These data suggest the LIAISON androstenedione assay may be a suitable alternative for the measurement of androstenedione in serum of adult patients with all advantages of a fully automated assay.

LC-MS/MS based profiling and dynamic modelling of the steroidogenesis pathway in adrenocarcinoma H295R cells

Endocrine disrupting chemicals have been reported to exert effects directly on enzymes involved in steroid biosynthesis. Here, we present a new liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for profiling the steroid metabolome of H295R human adrenocarcinoma cells. Our method can simultaneously analyse 19 precursors, intermediates and end-products, representing the adrenal steroid biosynthesis pathway. In order to obtain better insights into the processes of steroidogenesis, we investigated the dose-response relationship of forskolin, an activator of adenylate cyclase, on steroid production in H295R cells. We observed that 1.5 μM forskolin stimulated steroid production at approximately 50% of the maximum rate for most steroids. Hence, we studied the time course for steroid synthesis over 72 h in H295R cells that were stimulated with forskolin. At 24 h, we observed a peak in steroid levels for the intermediate metabolites, such as progesterone and pregnenolone, while end-products such as testosterone and cortisol continued to increase until 72 h. Finally, we show how global data provide a unique basis to develop a comprehensive, dynamic model for steroidogenesis using first order kinetics. The timeline data made it possible to estimate all reaction rate constants of the network. We propose this method as a unique and sensitive screening tool to identify effects on adrenal steroidogenesis by endocrine disrupting compounds.

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.

MECHANISMS IN ENDOCRINOLOGY: New concepts to further unravel adrenal insufficiency during critical illness

The concept of 'relative' adrenal insufficiency during critical illness remains a highly debated disease entity. Several studies have addressed how to diagnose or treat this condition but have often yielded conflicting results, which further fuelled the controversy. The main reason for the controversy is the fact that the pathophysiology is not completely understood. Recently, new insights in the pathophysiology of the hypothalamic-pituitary-adrenal axis response to critical illness were generated. It was revealed that high circulating levels of cortisol during critical illness are explained more by reduced cortisol breakdown than by elevated cortisol production. Cortisol production rate during critical illness is less than doubled during the day but lower than in healthy subjects during the night. High plasma cortisol concentrations due to reduced breakdown in turn reduce plasma ACTH concentrations via feedback inhibition, which with time may lead to an understimulation and hereby a dysfunction of the adrenal cortex. This could explain the high incidence of adrenal insufficiency in the prolonged phase of critical illness. These novel insights have created a new framework for the diagnosis and treatment of adrenal failure during critical illness that has redirected future research.

Role of mass spectrometry in steroid assays

In addition to protein hormones, steroids measurement constitutes the basis of modern endocrinology. Immunoassays have shown their limits in this field. In contrast, mass spectrometry shows an excellent sensitivity and specificity that make it the method of choice for steroids assays. The recent introduction of UHPLC-MS is a major advance which reinforces this position. In fact, mass spectrometry provides a lot of advantages such as determination of certain steroids in saliva, diagnosis of enzyme deficiencies, or measurement of molecules previously inaccessible like aldosterone. However, standardization is still needed to ensure good comparability of results between laboratories. In the future, mass spectrometry should not replace the immunoassays but rather complement it.

Analytical challenges for measuring steroid responses to stress, neurodegeneration and injury in the central nervous system

Levels of steroids in the adult central nervous system (CNS) show marked changes in response to stress, degenerative disorders and injury. However, their analysis in complex matrices such as fatty brain and spinal cord tissues, and even in plasma, requires accurate and precise analytical methods. Radioimmunoassays (RIA) and enzyme-linked immunosorbent assays, even with prepurification steps, do not provide sufficient specificity, and they are at the origin of many inconsistent results in the literature. The analysis of steroids by mass spectrometric methods has become the gold standard for accurate and sensitive steroid analysis. However, these technologies involve multiple purification steps prone to errors, and they only provide accurate reference values when combined with careful sample workup. In addition, the interpretation of changes in CNS steroid levels is not an easy task because of their multiple sources: the endocrine glands and the local synthesis by neural cells. In the CNS, decreased steroid levels may reflect alterations of their biosynthesis, as observed in the case of chronic stress, post-traumatic stress disorders or depressive episodes. In such cases, return to normalization by administering exogenous hormones or by stimulating their endogenous production may have beneficial effects. On the other hand, increases in CNS steroids in response to acute stress, degenerative processes or injury may be part of endogenous protective or rescue programs, contributing to the resistance of neural cells to stress and insults. The aim of this review is to encourage a more critical reading of the literature reporting steroid measures, and to draw attention to the absolute need for well-validated methods. We discuss reported findings concerning changing steroid levels in the nervous system by insisting on methodological issues. An important message is that even recent mass spectrometric methods have their limits, and they only become reliable tools if combined with careful sample preparation.

Mass spectrometric analysis of steroids: all that glitters is not gold

Steroid hormones are small molecules (MW around 300 Da) characterized by a large range of polarity and their analysis has always presented a serious challenge. Persistent problems with the specificity of conventional immunological methods are the cause of inconsistent results in the literature, a particularly problematic situation for healthcare decisions. At present, mass spectrometric methods have become the gold standard for accurate steroid profiling, and their advent will require the re-analysis of previously published data. However, it is a common misconception to consider the use of theses sophisticated technologies as a guarantee for accurate measures. Steroid analysis, especially in nervous tissues, indeed requires well-validated purification and separation steps before mass spectrometry, only then will mass spectrometric analysis be the absolute reference methodology.

LC–MS-based quantification of intact proteins: perspective for clinical and bioanalytical applications

Bioanalytical LC–MS for protein quantification is traditionally based on enzymatic digestion of the target protein followed by absolute quantification of a specific signature peptide relative to a stable-isotope labeled analog. The enzymatic digestion, nonetheless, limits rapid method development, sample throughput and turnaround time, and, moreover, makes that essential information regarding the biological function of the intact protein is lost. The recent advancements in high-resolution MS instrumentation and improved sample preparation techniques dedicated to protein clean-up raise the question to what extent LC–MS can be applied for quantitative bioanalysis of intact proteins. This review provides an overview of current and potential applications of LC–MS for intact protein quantification as well as the main limitations and challenges for broad application.

Cortisol metabolism in critical illness: implications for clinical care

PURPOSE OF REVIEW

Critical illness is uniformly characterized by elevated plasma cortisol concentrations, traditionally attributed exclusively to increased cortisol production driven by an activated hypothalamic pituitary adrenal axis. However, as plasma adrenocorticotropic hormone (ACTH) concentrations are often not elevated or even low during critical illness, alternative mechanisms must contribute.

RECENT FINDINGS

Recent investigations revealed that plasma clearance of cortisol is markedly reduced during critical illness, explained by suppressed expression and activity of the main cortisol metabolizing enzymes in liver and kidney. Furthermore, unlike previously inferred, cortisol production rate in critically ill patients was only moderately increased to less than double that of matched healthy subjects. In the face of low-plasma ACTH concentrations, these data suggest that other factors drive hypercortisolism during critical illness, which may suppress ACTH by feedback inhibition. These new insights add to the limitations of the current diagnostic tools to identify patients at risk of failing adrenal function during critical illness. They also urge to investigate the impact of lower hydrocortisone doses than those hitherto used.

SUMMARY

Recent novel insights reshape the current understanding of the hormonal stress response to critical illness and further underline the need for more studies to unravel the pathophysiology of adrenal (dys)functioning during critical illness.