High-throughput analysis of testosterone in serum samples by on-line solid phase extraction liquid chromatography-tandem mass spectrometry

Mass spectrometry in the clinical laboratory. A short journey through the contribution to the scientific literature by CCLM

Mass spectrometry (MS) has been a gold standard in the clinical laboratory for decades. Although historically refined to limited areas of study such as neonatal screening and steroid analysis, technological advancements in the field have resulted in MS becoming more powerful, versatile, and user-friendly than ever before. As such, the potential for the technique in clinical chemistry has exploded. The past two decades have seen advancements in biomarker detection for disease diagnostics, new methods for protein measurement, improved methodologies for reliable therapeutic drug monitoring, and novel technologies for automation and high throughput. Throughout this time, Clinical Chemistry and Laboratory Medicine has embraced the rapidly developing field of mass spectrometry, endeavoring to highlight the latest techniques and applications that have the potential to revolutionize clinical testing. This mini review will highlight a selection of these critical contributions to the field.

Development of LC-MS/MS Confirmatory Method for the Determination of Testosterone in Bovine Serum

Introduction

In the European Union the use of steroid growth promoters is prohibited under Council Directive 96/22/EC. For effective control of illegal use of natural steroids, highly sensitive analytical methods are required, because sex hormones can be present in very low concentrations in biological samples. The aim of the study was to develop a confirmatory method for the detection of testosterone in bovine serum at ppt level.

Material and Methods

17β-testosterone and internal standards of 17%-testosterone-d2 were extracted from serum samples with a mixture of tert-butyl methyl ether/petroleum ether and were directly analysed by an LC/MS/MS on QTRAP 5500 instrument with a TurboIon-Spray source operating in a positive ionisation mode. Chromatographic separation was achieved on the analytical column Inertsil® ODS-3 with an isocratic elution using mobile phase consisting of acetonitrile, methanol, and water. Method validation has been carried out in accordance with the Commission Decision 2002/657/EC.

Results

The method was characterised by good recovery (82%) and precision (R.S.D 17 %). Decision limit (CCα) and detection capability (CCβ) was 0.05 μg L⁻¹ and 0.09 μg L⁻¹ respectively. The method met the criteria set out in Commission Decision 2002/657/EC for the purpose of confirmation in terms of retention time and ion ratio in the whole range of its application.

Conclusions

The developed method is specific and sensitive, suitable for measuring the natural level of testosterone in blood of cattle and for use in routine control programme for the detection of this hormone in bovine serum.

Novel methodologies in analysis of small molecule biomarkers and living cells

Enzyme-linked immuno-sorbent assay (ELISA) is widely used for biomarker detection. A good biomarker can distinguish patients from healthy or benign diseases. However, the ELISA method is not suitable for small molecule or trace substance detection. Along with the development of new technologies, an increasing level of biomaterials, especially small molecules, will be identified as novel biomarkers. Quantitative immuno-PCR, chromatography-mass spectrometry, and nucleic acid aptamer are emerging methodologies for detection of small molecule biomarkers, even in living cells. In this review, we focus on these novel technologies and their potential for small molecule biomarkers and living cell analysis.

Total testosterone quantitative measurement in serum by LC-MS/MS

Reliable measurement of total testosterone is essential for the diagnosis, treatment and prevention of a number of hormone-related diseases affecting adults and children. A mass spectrometric method for testosterone determination in human serum was carefully developed and thoroughly validated. Total testosterone from 100 μL serum is released from proteins with acidic buffer and isolated by two serial liquid-liquid extraction steps. The first extraction step isolates the lipid fractions from an acidic buffer solution using ethyl acetate and hexane. The organic phase is dried down and reconstituted in a basic buffer solution. The second extraction step removes the phospholipids and other components by hexane extraction. Liquid chromatography-isotopic dilution tandem mass spectrometry is used to quantify the total testosterone. The sample preparation is automatically conducted in a liquid-handling system with 96-deepwell plates. The method limit of detection is 9.71 pmol/L (0.280 ng/dL) and the method average percent bias is not significantly different from reference methods. The performance of this method has proven to be consistent with the method precision over a 2-year period ranging from 3.7 to 4.8% for quality control pools at the concentrations 0.527, 7.90 and 30.7 nmol/L (15.2, 228, and 886 ng/dL), respectively. This method provides consistently high accuracy and excellent precision for testosterone determination in human serum across all clinical relevant concentrations.

Revisiting hyper- and hypo-androgenism by tandem mass spectrometry

Modern endocrinology is living a critical age of transition as far as laboratory testing and biochemical diagnosis are concerned. Novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) assays for steroid measurement in biological fluids have abundantly demonstrated their analytical superiority over immunometric platforms that until now have dominated the world of steroid hormones determination in clinical laboratories. One of the most useful applications of LC-MS/MS is in the hypogonadism and hyperandrogenism field: LC-MS/MS has proved particularly suitable for the detection of low levels of testosterone typical of women and children, and in general more reliable in accurately determining hypogonadal male levels. This technique also offers increased informative power by allowing multi-analytical profiles that give a more comprehensive picture of the overall hormonal asset. Several LC-MS/MS methods for testosterone have been published in the last decade, some of them included other androgen or more comprehensive steroid profiles. LC-MS/MS offers the concrete possibility of achieving a definitive standardization of testosterone measurements and the generation of widely accepted reference intervals, that will set the basis for a consensus on the diagnostic value of biochemical testing. The present review is aimed at summarizing technological advancements in androgen measurements in serum and saliva. We also provide a picture of the state of advancement of standardization of testosterone assays, of the redefinition of androgen reference intervals by novel assays and of studies using LC-MS/MS for the characterization and diagnosis of female hyperandrogenism and male hypogonadism.