Accuracy-based proficiency testing for testosterone measurements with immunoassays and liquid chromatography-mass spectrometry

Establishing metrological traceability for small molecule measurands in laboratory medicine

For molecules that can be well described metrologically in the sense of the definition of measurands, and which can also be recorded analytically as individual substances, reference measurement service traceability to a metrologically sound foundation is a necessity. The establishment of traceability chains must be initiated by National Metrology Institutes (NMIs) according to applicable standards; they are at the top and leading position in this concept. If NMIs are not in the position to take up this task, alternative approaches must be sought. Traceability initiatives established by in vitro device industry or academia must meet the quality standards of NMIs. Adherence to International Organization for Standardization (ISO) procedure 15193 must be a matter of course for the establishment of reference measurement procedures (RMPs). Certified reference material (CRM) characterization must be thorough, e.g., by the application of quantitative nuclear magnetic resonance measurements and by adherence to ISO 15194. Both for RMPs and CRMs Joint Committee for Traceability in Laboratory Medicine (JCTLM) listing must be the ultimate goal. Results must be shared in a transparent manner to allow other stakeholders including NMIs to reproduce and disseminate the reference measurement procedures.

Evaluation of testosterone, estradiol and progesterone immunoassay calibrators by liquid chromatography mass spectrometry

OBJECTIVES

In clinical practice, steroid measurements are performed mainly by direct, non-extraction immunoassays adapted to high throughput, automated immunoassay platforms and employing secondary calibrators. The accuracy of such steroid immunoassays is limited by cross-reactivity with structurally related steroids and nonspecific matrix interference as well as the metrological traceability of manufacturer supplied calibrators. The accuracy of steroid immunoassay calibrators has been little investigated by independent chemical methods.

METHODS

Steroid concentrations of 41 calibrators (4-6 replicates per calibrator) supplied by four manufacturers for use in testosterone (T), estradiol (E2), and progesterone (P4) commercial immunoassays were measured by ultra-pressure liquid chromatography-mass spectrometry (UPLC-MS).

RESULTS

Among 14 non-zero T calibrators, six (43 %) deviated significantly from the label concentration with 29 % outside 20 % of it. Among 14 E2 calibrators, eight (57 %) deviated significantly, whereas seven (50 %) were outside 20 % of the label concentration. Among 11 P4 calibrators, eight (73 %) deviated significantly whereas four (36 %) were outside within 20 % of the label concentration.

CONCLUSIONS

We conclude that inaccurate calibration of manufacturer's supplied standards may contribute to inaccuracy of commercial direct steroid immunoassays.

Mass spectrometry redefines optimal testosterone thresholds in prostate cancer patients undergoing androgen deprivation therapy

BACKGROUND

Androgen deprivation therapy (ADT) is the standard of care for prostate cancer treatment. Studies suggest that patients with testosterone levels below 0.7 nM have a longer time to castration resistance. Using the most accurate testosterone measurement method, namely mass spectrometry (MS), we sought to determine if a lower testosterone level under ADT could be associated with longer time to castration resistance.

METHODS

This retrospective study included 138 prostate cancer patients undergoing noncurative continuous ADT for which we had access to testosterone measurements assessed by MS. For 108 samples, paired immunoassays (IA) testosterone measurement was available. Primary outcome was time to castration-resistant prostate cancer (CRPC). The Contal and O'Quigley method was used to determine the optimal testosterone castration cut-off point considering the outcome and time-to-event variables. Relationship between testosterone levels assessed either by IA or MS and time to CRPC was evaluated using Cox regression.

RESULTS

Mean testosterone level was 0.370 nM by IA and 0.275 nM as assessed by MS. The optimal testosterone cut-off point identified to predict time to CRPC was of 0.705 nM for IA and of 0.270 nM for MS. While no significant difference for time to CRPC was found between patients showing IA testosterone level ≥0.705 nM versus <0.705 nM (hazard ratio [HR]: 1.579; 95% confidence interval [CI]: 0.908-2.745), patients with MS testosterone ≥0.270 nM had an increased risk of progression to CRPC compared to MS testosterone <0.270 nM in univariate (HR: 1.717; 95% CI: 1.160-2.541) and multivariate analysis (HR: 1.662; 95% CI: 1.043-2.648).

CONCLUSIONS

The higher sensitivity of MS testosterone measurement methods allows the identification of a lower castration threshold and leads to early identification of patients more likely to progress to CRPC. These patients would likely benefit from treatment intensification by androgen receptor axis-targeted therapies to delay disease progression.

Suggested Cutoff Point for Testosterone by Liquid Chromatography with Tandem Mass Spectrometry (LC-MS/MS) after Stimulation with Recombinant Human Chorionic Gonadotropin

The human chorionic gonadotropin (hCG) stimulation test that evaluates gonadal steroidogenesis is crucial in the assessment of patients with 46,XY disorders of sex development (DSD). This study aimed to determine a testosterone (T) cutoff level that indicates an adequate testicular function using LC-MS/MS after stimulation with recombinant human chorionic gonadotropin (rhCG) in a single dose. Nineteen prepubertal children with 46,XY DSD and normal T secretion were evaluated. T and dihydrotestosterone (DHT) levels were measured by liquid chromatography technique with tandem mass spectrometry (LC-MS/MS) before and 7 days after rhCG application at 250 µg. We suggest 0.89 ng/mL as the cutoff point for T after rhCG stimulation analyzed by LC-MS/MS.

Clinical Usefulness of Ultraperformance Liquid Chromatography-Tandem Mass Spectrometry Method for Low Serum Testosterone Measurement

Background

Mass spectrometry methods exhibit higher accuracy and lower variability than immunoassays at low testosterone concentrations. We developed and validated an ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) assay for quantifying serum total testosterone.

Methods

We used an ExionLC UPLC (Sciex, Framingham, MA, USA) system and a Sciex Triple Quad 6500+ (Sciex) MS/MS system in electrospray ionization and positive ion modes with multiple reaction monitoring transitions to evaluate precision, accuracy, linearity, lower limit of quantitation (LLOQ), carryover, ion suppression, stability, and reference intervals. For method comparison, we measured serum testosterone concentrations using this method in 40 subjects whose testosterone concentrations ranged from 0.14 to 55.48 nmol/L as determined using the Architect i2000 immunoassay (Abbott Diagnostics, Abbott Park, IL, USA) and in an additional 160 sera with testosterone concentrations <1.67 nmol/L.

Results

The intra- and inter-run precision CVs were <2.81%, and the accuracy bias values were <3.85%, which were all acceptable. The verified linear interval was 0.03-180.84 nmol/L; the LLOQ was 0.03 nmol/L. No significant carryover and ion suppression were observed. The testosterone in serum was stable at 4°C, at -20°C, and after three freeze-thaw cycles. The reference intervals were successfully verified. The correlation was good at testosterone concentrations of 0.14-55.48 nmol/L; however, the Architect assay showed positive percent bias at concentrations <1.67 nmol/L.

Conclusions

The UPLC-MS/MS assay shows acceptable performance, with a lower LLOQ than the immunoassay. This method will enable the quantitation of low testosterone concentrations.

Reference intervals for free testosterone in adult men measured using a standardized equilibrium dialysis procedure

BACKGROUND

Free testosterone (FT) determination may be helpful in evaluating men suspected of testosterone deficiency especially in conditions with altered binding-protein concentrations. However, methods for measuring FT by equilibrium dialysis and reference intervals vary among laboratories.

OBJECTIVE

To determine reference intervals for FT in healthy, nonobese men by age groups as well as in healthy young men, 19-39 years, using a standardized equilibrium dialysis procedure METHODS: We measured FT in 145 healthy, nonobese men, 19 years or older, using a standardized equilibrium dialysis method performed for 16-h at 37°C using undiluted serum and dialysis buffer that mimicked the ionic composition of human plasma. FT in dialysate was measured using a CDC-certified liquid chromatography tandem mass spectrometry assay.

RESULTS

In healthy nonobese men, the 2.5th, 10th, 50th, 90th, and 97.5th percentile values for FT were 66, 91, 141, 240, and 309 pg/ml, respectively; corresponding values for men, 19-39 years, were 120, 128, 190, 274, and 368 pg/ml, respectively. FT levels by age groups exhibit the expected age-related decline. FT levels were negatively associated with body mass index, age, and sex hormone-binding globulin (SHBG) levels. Percent FT was lower in middle-aged and older men than young men adjusting for SHBG level.

DISCUSSION

Further studies are needed to determine how these reference intervals apply to the diagnosis of androgen deficiency in clinical populations and in men of different races and ethnicities in different geographic regions.

CONCLUSION

Reference intervals for free FT levels (normative range 66-309 pg/ml [229-1072 pmol/L] in all men and 120-368 pg/ml [415-1274 pmol/L] in men, 19-39 years), measured using a standardized equilibrium dialysis method in healthy nonobese men, provide a rational basis for categorizing FT levels. These intervals require further validation in other populations, in relation to outcomes, and in randomized trials.

Effects of testosterone treatment on clitoral haemodynamics in women with sexual dysfunction

PURPOSE

To explore the effects of 6-month systemic testosterone (T) administration on clitoral color Doppler ultrasound (CDU) parameters in women with female sexual dysfunction (FSD).

METHODS

81 women with FSD were retrospectively recruited. Data on CDU parameters at baseline and after 6 months with four different treatments were available and thus further longitudinally analyzed: local non-hormonal moisturizers (NH group), n = 37; transdermal 2% T gel 300 mcg/day (T group), n = 23; local estrogens (E group), n = 12; combined therapy (T + E group), n = 9. Patients underwent physical, laboratory, and genital CDU examinations at both visits and completed different validated questionnaires, including the Female Sexual Function Index (FSFI).

RESULTS

At 6-month visit, T therapy significantly increased clitoral artery peak systolic velocity (PSV) when compared to both NH (p < 0.0001) and E (p < 0.0001) groups. A similar increase was found in the T + E group (p = 0.039 vs. E). In addition, T treatment was associated with significantly higher FSFI desire, pain, arousal, lubrication, orgasm, and total scores at 6-month visit vs. baseline. Similar findings were observed in the T + E group. No significant differences in the variations of total and high-density lipoprotein-cholesterol, triglycerides, fasting glycemia, insulin and glycated hemoglobin levels were found among the four groups. No adverse events were observed.

CONCLUSION

In women complaining for FSD, systemic T administration, either alone or combined with local estrogens, was associated with a positive effect on clitoral blood flow and a clinical improvement in sexual function, showing a good safety profile.

TRIAL REGISTRATION NUMBER

NCT04336891; date of registration: April 7, 2020.

Using mass spectrometry to overcome the longstanding inaccuracy of a commercially-available clinical testosterone immunoassay

Accurate measurement of testosterone is important for the diagnosis of gonadal disorders in men, women, and children. Testosterone measurement has limited accuracy at low concentrations by most commercially available immunoassays. We aimed to develop an LC-MS/MS assay to address the inaccuracy of the in-house immunoassay observed over the past decade and to replace it with the new assay. Testosterone in serum/plasma was extracted with commercial supported liquid extraction plates. Method validation was performed following the CLSI C62-A guideline. A total of 126 samples were used for method comparison between the Beckman UniCel DxI immunoassay and LC-MS/MS. Results by immunoassay were 20% lower compared with LC-MS/MS and had minimal correlation (R² = 0.403) with LC-MS/MS below 100 ng/dL. When comparing specimens from the Accuracy-Based Survey from the College of American Pathologists, the newly developed assay agreed well with the CDC reference measurement procedure. In summary, immunoassay measurement of testosterone can be significantly inaccurate, especially at low concentrations. The newly developed LC-MS/MS assay provides accurate results across the entire measurable range.

Recommendations for proficiency testing criteria for hemoglobin A1c based on the Shanghai Center for Clinical Laboratory's study

OBJECTIVES

The US Centers for Medicare & Medicaid Services proposed in 2019 that glycated hemoglobin A_1c (HbA_1c) be a CLIA'88 regulated analyte. People who commented expressed concerns that the proposed acceptance limit (AL, HbA_1c in NGSP unit) ±10% for proficiency testing (PT) would be unable to maintain already improved analytical performance and guarantee the clinical utility of HbA_1c testing. Assessing impact of various ALs on PT performance is needed to provide scientific evidence for adopting an appropriate AL.

METHODS

Ten patient EDTA-whole blood specimens were distributed to 318 and 336 laboratories in the 2018 and 2019 PT events organized by Shanghai Center for Clinical Laboratory (SCCL). HbA_1c concentrations were measured by participants using various methodologies commonly used in the USA and China. Targets were determined using secondary reference measurement procedures (SRM) at SCCL. "Failed Results" were those outside the SRM-defined target ± AL (5% through 10%). Laboratories with Failed Results ≥2 out of five samples per PT event obtained Event Unsatisfactory Status.

RESULTS

HbA_1c target values ranged 33.3 mmol/mol (5.2 NGSP%) -102.2 mmol/mol (11.5 NGSP%) for 2018 event, and 33.3 mmol/mol (5.2 NGSP%) -84.7 mmol/mol (9.9 NGSP%) for 2019 event. Overall Laboratory Event Unsatisfactory Rates were 11.3-12.2%, 4.8-5.3%, 0.9-3.1%, 0.6-2.2%, 0.6-1.4% and 0.6-1.4%, at AL of ±5, ±6, ±7, ±8, ±9 and ±10%, respectively.

CONCLUSIONS

The AL (in NGSP unit) of ±6% or ±7% for PT evaluation of HbA_1c results would be appropriate, with satisfactory event scores for about 95% of participant laboratories in a PT event.

Measurement of Serum Testosterone in Nondiabetic Young Obese Men: Comparison of Direct Immunoassay to Liquid Chromatography-Tandem Mass Spectrometry

Hypoandrogenemia, a frequent finding in men with obesity, is defined by low concentrations of serum testosterone. Although immunoassay (IA) is the most used method for the determination of this steroid in clinical practice, liquid chromatography-mass spectrometry (LC-MS/MS) is considered a more reliable method. In this study, we aimed to compare IA versus LC-MS/MS measurement for the diagnosis of hypoandrogenemia in a cohort of 273 nondiabetic young obese men. Mean total testosterone (TT) levels were 3.20 ± 1.24 ng/mL for IA and 3.78 ± 1.4 ng/mL for LC-MS/MS. 53.7% and 26.3% of patients were classified as presenting hypoandrogenemia with IA and LC-MS/MS, respectively. Considering LC-MS/MS as the reference method, sensitivity and specificity of IA were 91.4% (95% CI 82.3-96.8) and 61.1% (95% CI 54.0-67.8), respectively. IA presented an AUC of 0.879 (95% CI 0.83-0.928). Multivariate regression analysis indicated that sex hormone-binding globulin (SHBG) concentrations (p = 0.002) and insulin resistance (p = 0.008) were factors associated with discrepant IA values. In conclusion, the determination of TT by IA in nondiabetic young men with obesity yields lower concentrations of TT than LC-MS/MS, resulting in an equivocal increased diagnosis of hypoandrogenemia, which could lead to inaccurate diagnosis and unnecessary treatment.

Androgens by immunoassay and mass spectrometry in children with 46,XY disorder of sex development

OBJECTIVE

Steroid measurement is a challenge in pediatric endocrinology. Currently, liquid chromatography with tandem mass spectrometry (LC-MS/MS) is considered a gold standard for this purpose. The aim of this study was to compare both LC-MS/MS and immunoassay (IA) for androgens before and after human recombinant chorionic gonadotropin (rhCG) stimulus in children with 46,XY disorders of sex development (DSD).

METHODS

Nineteen patients with 46,XY DSD were evaluated; all of them were prepubertal and non-gonadectomized. Testosterone, dihydrotestosterone (DHT), DHEA and androstenedione were measured by IA and LC-MS/MS before and 7 days after rhCG injection. The correlation between IA and LC-MS/MS was analyzed by the intraclass correlation coefficient (ICC) and Spearman's rank correlation coefficient (SCC). For concordance analysis the Passing and Bablok (PB) regression and the Bland and Altman (BA) method were used.

RESULTS

Testosterone showed excellent correlation (ICC = 0.960 and SCC = 0.964); DHT showed insignificant and moderate correlations as indicated by ICC (0.222) and SCC (0.631), respectively; DHEA showed moderate correlation (ICC = 0.585 and SCC = 0.716); and androstenedione had poor and moderate correlations in ICC (0.363) and SCC (0.735), respectively. Using the PB method, all hormones showed a linear correlation, but proportional and systematic concordance errors were detected for androstenedione, systematic errors for testosterone and no errors for DHEA and DHT. By the BA method, there was a trend of IA to overestimate testosterone and androstenedione and underestimate DHEA and DHT when compared to LC-MS/MS.

CONCLUSION

Traditional IA should be replaced by LC-MS/MS for the androgens measurement in prepubertal children whenever is possible.

An audit of the measurement and reporting of male testosterone levels in UK clinical biochemistry laboratories

INTRODUCTION

A number of guidance documents have been published in recent years for the diagnosis and management of hypogonadism (HG). Laboratory practice has a major role in supporting guidelines with accurate and precise serum total testosterone (TT) methods and standardised pre- and post-analytical protocols. Our study investigated whether laboratory practice currently supports the management guidelines for HG.

METHODS

An internet-based questionnaire survey of senior laboratory biochemists (UK/Republic of Ireland) was conducted (April-May 2018). Questions reflected sampling, laboratory practice, reference ranges and reporting of results. The results were analysed in conjunction with data obtained from the UK National External Quality Assurance Service (UK NEQAS) on testosterone assay performance.

RESULTS

Analyses of 96 laboratory surveys returned the following: 74 laboratories stated that the optimal sampling time was communicated to users; 81 laboratories used immunoassays; 76 laboratories included reference ranges for adult men (31 had dual/multiple age-related intervals). Wide variability in lower/upper limits was evident in the common immunoassays; the majority of reference ranges were from manufacturers (50.0%) or historical (18.8%). Action limits based on TT levels were used by 64 laboratories, but 63 did not report a borderline range as suggested by the guidelines. Protocols for cascading tests based on TT were evident in 58 laboratories, with 50 laboratories offering estimated free testosterone; interpretative comments were provided by 67 laboratories, but no references were made to the management guidelines. Data from UK NEQAS demonstrated considerable variation in testosterone assay performance.

CONCLUSIONS

Our survey has highlighted inconsistencies that could lead to HG (and other conditions requiring measurement of TT) not being managed appropriately. The results from this survey and from UK NEQAS reinforce the requirement for action to be considered regarding the standardisation of testosterone assays and harmonisation of laboratory practice.

Impact of Sequencing of Androgen Suppression and Radiation Therapy on Testosterone Recovery in Localized Prostate Cancer

PURPOSE

We performed a secondary analysis of a phase 3 randomized trial to determine the influence of sequencing of radiation therapy and androgen deprivation therapy (ADT) on posttreatment testosterone recovery and implications of testosterone recovery on subsequent relapse.

METHODS AND MATERIALS

Patients with localized prostate cancer with Gleason score ≤7, clinical stage T1b to T3a, and prostate-specific antigen <30 ng/mL were randomized to neoadjuvant and concurrent ADT for 6 months starting 4 months before prostate radiation therapy (NHT arm) or concurrent and adjuvant ADT for 6 months starting simultaneously with radiation therapy (CAHT arm). Full testosterone recovery (FTR) was defined as recovery of testosterone to >10.5 nmol/L in patients with baseline ≥10.5 nmol/L or to baseline level in patients with baseline <10.5 nmol/L. Restricted mean survival time (RMST) since ADT initiation to supracastrate testosterone level (>1.7 nmol/L), and to FTR was compared between the arms using a truncation time point of 36 months.

RESULTS

The adjusted difference in RMST to supracastrate testosterone between the CAHT and NHT arm was 1.5 months (95% confidence interval [CI], 0.5-2.5; P = .005). No difference was noted in RMST to FTR between the arms (18.7 vs 18.5 months, adjusted difference: 0.5; 95% CI, -1.4 to 2.4; P = .61). There was no evidence of heterogeneity of treatment effect (interaction P = .76) on risk of relapse over subgroups stratified by testosterone recovery to supracastrate level at 15 months after start of ADT. Based on a multistate Markov model, no independent effect of time to FTR on risk of subsequent relapse was observed (adjusted hazard ratio: 1.02; 95% CI, 0.96-1.08).

CONCLUSIONS

Patients should be counseled that an additional 12 months on average is needed for FTR to occur after treatment with prostate radiation therapy and 6 months of ADT. This is independent of the sequencing of ADT and radiation therapy. Furthermore, recovery of testosterone does not appear to affect the risk of subsequent relapse.

Management of Patients with Advanced Prostate Cancer: Report of the Advanced Prostate Cancer Consensus Conference 2019

BACKGROUND

Innovations in treatments, imaging, and molecular characterisation in advanced prostate cancer have improved outcomes, but there are still many aspects of management that lack high-level evidence to inform clinical practice. The Advanced Prostate Cancer Consensus Conference (APCCC) 2019 addressed some of these topics to supplement guidelines that are based on level 1 evidence.

OBJECTIVE

To present the results from the APCCC 2019.

DESIGN, SETTING, AND PARTICIPANTS

Similar to prior conferences, experts identified 10 important areas of controversy regarding the management of advanced prostate cancer: locally advanced disease, biochemical recurrence after local therapy, treating the primary tumour in the metastatic setting, metastatic hormone-sensitive/naïve prostate cancer, nonmetastatic castration-resistant prostate cancer, metastatic castration-resistant prostate cancer, bone health and bone metastases, molecular characterisation of tissue and blood, inter- and intrapatient heterogeneity, and adverse effects of hormonal therapy and their management. A panel of 72 international prostate cancer experts developed the programme and the consensus questions.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The panel voted publicly but anonymously on 123 predefined questions, which were developed by both voting and nonvoting panel members prior to the conference following a modified Delphi process.

RESULTS AND LIMITATIONS

Panellists voted based on their opinions rather than a standard literature review or formal meta-analysis. The answer options for the consensus questions had varying degrees of support by the panel, as reflected in this article and the detailed voting results reported in the Supplementary material.

CONCLUSIONS

These voting results from a panel of prostate cancer experts can help clinicians and patients navigate controversial areas of advanced prostate management for which high-level evidence is sparse. However, diagnostic and treatment decisions should always be individualised based on patient-specific factors, such as disease extent and location, prior lines of therapy, comorbidities, and treatment preferences, together with current and emerging clinical evidence and logistic and economic constraints. Clinical trial enrolment for men with advanced prostate cancer should be strongly encouraged. Importantly, APCCC 2019 once again identified important questions that merit assessment in specifically designed trials.

PATIENT SUMMARY

The Advanced Prostate Cancer Consensus Conference provides a forum to discuss and debate current diagnostic and treatment options for patients with advanced prostate cancer. The conference, which has been held three times since 2015, aims to share the knowledge of world experts in prostate cancer management with health care providers worldwide. At the end of the conference, an expert panel discusses and votes on predefined consensus questions that target the most clinically relevant areas of advanced prostate cancer treatment. The results of the voting provide a practical guide to help clinicians discuss therapeutic options with patients as part of shared and multidisciplinary decision making.

Ramifications of variability in sex hormone-binding globulin measurement by different immunoassays on the calculation of free testosterone

Objective

Sex hormone-binding globulin (SHBG) is a glycoprotein which binds hormones such as testosterone. Around 97% of circulating testosterone is bound to SHBG or albumin and is therefore biologically unavailable; 2–3% of testosterone is free. Free testosterone is very technically challenging to quantify; in order to circumvent this problem, equations using testosterone and SHBG are used to estimate free testosterone. We decided to determine the effect of using different SHBG immunoassays on calculated free testosterone results.

Design

Anonymized surplus serum samples were analysed for SHBG on four different immunoassay platforms (Abbott Architect, Roche, Beckman and Siemens). The SHBG results were used to generate a Vermeulen calculated free testosterone.

Results

Beckman Access and Siemens Centaur both gave results close to the overall mean. Roche gave the highest SHBG concentrations with Abbott Architect producing the lowest results. Abbott Architect gave the highest calculated free testosterone results, followed by Beckman. Roche gave the lowest results. Sixty-five per cent of male samples had low calculated free testosterone and 27.5% of the females had high calculated free testosterone using the SHBG from the Abbott assay compared with 69% low male calculated free testosterone and 20% high female calculated free testosterone with the Roche assay.

Conclusion

Our results have shown significant differences in SHBG results produced by different analysers and subsequently the calculated free testosterone, which may affect result interpretation if method-specific reference ranges for calculated free testosterone are not used. Care should be taken to ensure reference ranges are appropriate for the analyser used to avoid misdiagnosis of hypo or hyperandrogenism, and ensure patients get the most appropriate treatment.

Accuracy-Based Vitamin D Survey: Six Years of Quality Improvement Guided by Proficiency Testing

CONTEXT.—

The goal of the College of American Pathologists Accuracy-Based Proficiency Testing Program is to promote the quality, standardization, and harmonization of clinical laboratory results through proficiency testing specimens that are free from matrix effects, have target values that are traceable to reference methods, and that probe the limitations of current methods.

OBJECTIVE.—

To summarize the first 6 years of the Accuracy-Based Vitamin D Survey and highlight key insights from the data generated as it relates to assay performance.

DESIGN.—

Accuracy-based challenges were created by using pooled human serum samples. Certain samples were derived from participants in an institutional review board-approved protocol in which vitamin D-deficient participants were treated with ergocalciferol (vitamin D₂). Reference targets for the survey were set by the Centers for Disease Control and Prevention using isotope-dilution liquid chromatography-tandem mass spectrometry. Each method was compared with the reference method procedure over the course of the program (n = 43 proficiency testing samples).

RESULTS.—

Linear regression versus the reference method procedure revealed proportional biases across the methods, ranging from 0.0% to 16.7%. Pearson correlation coefficients (r²) ranged from 0.902 to 0.996. Results were influenced by the concentration of 25-hydroxyvitamin D₂ as well as the C-3 epimer of 25-hydroxyvitamin D₃. During the 6 years, 2 manufacturers altered their assays to match the reference method procedure more closely.

CONCLUSIONS.—

There is considerable bias, both proportional bias and sample-specific matrix effects, affecting many assays. This ongoing accuracy-based proficiency testing program for vitamin D will provide the data needed for laboratories and manufacturers to improve their assays and thereby patient care.

Androgens in women - critical evaluation of the methods for their determination in diagnostics of endocrine disorders

The androgens dehydroepiandrosterone sulfate, dehydro-epiandrosterone, androstenedione and testosterone are routinely assessed in women, and circulating levels of these androgens reflect their production. These androgens are measured in most laboratories using various immuno-analytical methods. Recently, however, androgen assays have begun to be performed using gas or liquid chromatography combined with mass spectrometry. To better understand the difficulties and issues of androgen laboratory diagnostics, it is important to assess each of the methods used, how and why they were introduced into practice, and their advantages, limits, historic milestones and current status. It is also necessary to understand how reference ranges are determined and specifics arising from the physiology of individual androgens. Here we present a summary and discussion of these issues.

New Biomarkers to Evaluate Hyperandrogenemic Women and Hypogonadal Men

Androgens can have variable effects on men and women. Women may be evaluated for androgen excess for several reasons. Typically, young premenopausal women present with clinical symptoms of hirsutism, alopecia, irregular menses, and/or infertility. The most common cause of these symptoms is polycystic ovary syndrome. After menopause, even though ovaries stop producing estrogen, they continue to produce androgen, and women can have new onset of hirsutism and alopecia. Laboratory evaluation involves measurement of the major ovarian and adrenal androgens. In women, age, phase of the menstrual cycle, menopausal status, obesity, metabolic health, and sex hormone-binding proteins significantly affect total-androgen levels and complicate interpretation. This review will summarize the clinically relevant evaluation of hyperandrogenemia at different life stages in women and highlight pitfalls associated with interpretation of commonly used hormone measurements. Hypogonadism in men is a clinical syndrome characterized by low testosterone and/or low sperm count. Symptoms of hypogonadism include decreased libido, erectile dysfunction, decreased vitality, decreased muscle mass, increased adiposity, depressed mood, osteopenia, and osteoporosis. Hypogonadism is a common disorder in aging men. Hypogonadism is observed rarely in young boys and adolescent men. Based on the defects in testes, hypothalamus, and/or pituitary glands, hypogonadism can be broadly classified as primary, secondary, and mixed hypogonadism. Diagnosis of hypogonadism in men is based on symptoms and laboratory measurement. Biomarkers in use/development for hypogonadism are classified as hormonal, Leydig and Sertoli cell function, semen, genetic/RNA, metabolic, microbiome, and muscle mass-related. These biomarkers are useful for diagnosis of hypogonadism, determination of the type of hypogonadism, identification of the underlying causes, and therapeutic assessment. Measurement of serum testosterone is usually the most important single diagnostic test for male hypogonadism. Patients with primary hypogonadism have low testosterone and increased luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Patients with secondary hypogonadism have low testosterone and low or inappropriately normal LH and FSH. This review provides an overview of hypogonadism in men and a detailed discussion of biomarkers currently in use and in development for diagnosis thereof.

Testosterone suppression in the treatment of recurrent or metastatic prostate cancer - A Canadian consensus statement

Testosterone suppression, achieved through orchiectomy or medically induced androgen-deprivation therapy (ADT), is a standard treatment for men with recurrent and metastatic prostate cancer. Current assay methods demonstrate the capacity for testosterone suppression to <0.7 nmol/l, and clinical data support improved outcomes from ADT when lower levels are achieved. Practical clinical guidelines are warranted to facilitate adoption of 0.7 nmol/l as the new standard castrate testosterone level.A pan-Canadian group of experts, representing diverse clinical specialties, identified key clinical issues, searched and reviewed relevant literature, and developed consensus statements on testosterone suppression for the treatment of prostate cancer. The expert panel found that current evidence supports the clinical benefit of achieving low testosterone levels during ADT, and encourage adoption of ≤0.7 nmol/l as a new castrate level threshold. The panel recommends regular monitoring of testosterone (e.g., every 3-6 months) and prostate-specific antigen (PSA) levels as clinically appropriate (e.g., every 3-6 months) during ADT, with reassessment of therapeutic strategy if testosterone is not suppressed or if PSA rises regardless of adequate testosterone suppression. The panel also emphasizes the need for greater awareness and education regarding testosterone assay specifications, and strongly promotes the use of mass spectrometry-based assays to ensure accurate measurement of testosterone at castrate levels.