Design, methods and demographics from phase I of Alberta's Tomorrow Project cohort: a prospective cohort profile.

BACKGROUND: Prospective cohorts have the potential to support multifactorial, health-related research, particularly if they are drawn from the general population, incorporate active and passive follow-up and permission is obtained to allow access by researchers to data repositories. This paper describes Phase I of the Alberta's Tomorrow Project cohort, a broad-based research platform designed to support investigations into factors that influence cancer and chronic disease risk. METHODS: Adults aged 35-69 years living in Alberta, Canada, with no previous cancer diagnosis other than nonmelanoma skin cancer were recruited to the project by telephone-based random digit dialling. Participants were enrolled if they returned a Health and Lifestyle Questionnaire. Past year diet and physical activity questionnaires were mailed 3 months after enrolment. Consent was sought for active follow-up and linkage with administrative databases. Depending on enrolment date, participants were invited to complete up to 2 follow-up questionnaires (2004 and 2008). RESULTS: Between 2001 and 2009, 31 072 (39% men) participants (mean age 50.2 [± 9.2] yr) were enrolled and 99% consented to linkage with administrative databases. Participants reported a wide range of educational attainment and household income. Compared with provincial surveillance data from the Canadian Community Health Survey, Alberta's Tomorrow Project participants had higher body mass index, lower prevalence of smoking and similar distribution of chronic health conditions. Follow-up questionnaires were completed by 83% and 72% of participants in 2004 and 2008, respectively. Robust quality control measures resulted in low frequencies of missing data. INTERPRETATION: Alberta's Tomorrow Project provides a robust platform, based on a prospective cohort design, to support research into risk factors for cancer and chronic disease.

Free estradiol and sex hormone-binding globulin.

SHBG is a plasma protein that participates in the regulation of free estradiol and free testosterone in plasma. We discuss the concept of the nature of a free estradiol and how best to ascertain its value. It can be measured or calculated; the ways in which this can be done are explored along with the advantages and disadvantages of each.

Androgen therapy in women: a reappraisal: an Endocrine Society clinical practice guideline.

OBJECTIVE: To update practice guidelines for the therapeutic use of androgens in women. PARTICIPANTS: A Task Force appointed by the Endocrine Society, American Congress of Obestricians and Gynecologists (ACOG), American Society for Reproductive Medicine (ASRM), European Society of Endocrinology (ESE), and International Menopause Society (IMS) consisting of six experts, a methodologist, and a medical writer. EVIDENCE: The Task Force commissioned two systematic reviews of published data and considered several other existing meta-analyses and trials. The GRADE methodology was used; the strength of a recommendation is indicated by a number "1" (strong recommendation, we recommend) or "2" (weak recommendation, we suggest). CONSENSUS PROCESS: Multiple e-mail communications and conference calls determined consensus. Committees of the Endocrine Society, ASRM, ACOG, ESE, and IMS reviewed and commented on the drafts of the guidelines. CONCLUSIONS: We continue to recommend against making a diagnosis of androgen deficiency syndrome in healthy women because there is a lack of a well-defined syndrome, and data correlating androgen levels with specific signs or symptoms are unavailable. We recommend against the general use of T for the following indications: infertility; sexual dysfunction other than hypoactive sexual desire disorder; cognitive, cardiovascular, metabolic, or bone health; or general well-being. We recommend against the routine use of dehydroepiandrosterone due to limited data concerning its effectiveness and safety in normal women or those with adrenal insufficiency. We recommend against the routine prescription of T or dehydroepiandrosterone for the treatment of women with low androgen levels due to hypopituitarism, adrenal insufficiency, surgical menopause, pharmacological glucocorticoid administration, or other conditions associated with low androgen levels because there are limited data supporting improvement in signs and symptoms with therapy and no long-term studies of risk. Evidence supports the short-term efficacy and safety of high physiological doses of T treatment of postmenopausal women with sexual dysfunction due to hypoactive sexual desire disorder. Importantly, endogenous T levels did not predict response to therapy. At present, physiological T preparations for use in women are not available in many countries including the United States, and long-term safety data are lacking. We recommend that any woman receiving T therapy be monitored for signs and symptoms of androgen excess. We outline areas for future research. Ongoing improvement in androgen assays will allow a redefinition of normal ranges across the lifespan; this may help to clarify the impact of varying concentrations of plasma androgens on the biology, physiology, and psychology in women and lead to indications for therapeutic interventions.

Challenges to the measurement of estradiol: an endocrine society position statement.

OBJECTIVE: The objective of the study was to evaluate the current state of clinical assays for estradiol in the context of their applications. PARTICIPANTS: The participants were appointed by the Council of The Endocrine Society and charged with attaining the objective using published data and expert opinion. EVIDENCE: Data were gathered from published sources via online databases (principally PubMed, Ovid MEDLINE, Google Scholar), and the clinical and laboratory experience of the participants. CONSENSUS PROCESS: The statement was an effort of the committee and was reviewed by each member. The Clinical Affairs Committee, the Council of The Endocrine Society, and JCEM reviewers reviewed the manuscript and made recommendations. CONCLUSIONS: The measurement of estradiol in biological fluids is important in human biology from cradle to grave. In addition to its centrality in sexual development, it has significant effects on skin, blood vessels, bone, muscle, coagulation, hepatic cells, adipose tissue, the kidney, the gastrointestinal tract, brain, lung, and pancreas. Alterations in its plasma concentration have been implicated in coronary artery disease, stroke, and breast cancer. Although modern immunoassays and liquid chromatography/tandem mass spectrometry-based methods for estradiol are reasonably well suited to the diagnosis and management of infertility (nonetheless, imprecision and method-to-method differences remain problematic), the very low concentrations that appear to be crucial in nonreproductive tissues are a separate and more difficult issue. Such levels of estradiol are too low to be routinely measured accurately or precisely, and further evolution of analytical methods and the way in which estradiol is standardized is needed.

Toward excellence in testosterone testing: a consensus statement.

BACKGROUND: Testosterone assays are widely used. However, deficiencies in these assays limit their broad and effective implementation and threaten the health of those patients whose medical care relies upon its accurate measurement. Furthermore, the translation of research findings into information useful for patient care, such as new evidence-based clinical guidelines, is not possible unless both research and clinical assays are held to higher standards than are currently required. A group of concerned stakeholders was convened to address this problem. METHODS: Representatives of multiple professional societies, government, and industry, having a stake in ensuring that testosterone levels are measured accurately and reliably, met to identify goals, objectives, and actions necessary to bring about the standardization of assays for testosterone. RESULTS: To ensure highly accurate testosterone testing that will result in improved diagnosis, treatment, and prevention of disease through the use of standardized assays, a series of recommendations were agreed upon. The recommendations included the following: technical improvements for assay standardization; education of health care providers, patients, and all others concerned with testosterone testing; plans to encourage all concerned journals, government agencies, and health insurance companies to support this effort; and encouragement to manufacturers to develop better and more cost effective assays. CONCLUSION: A preliminary timeline was set out to implement the recommendations of the Group.

Interactions of sex hormone-binding globulin with target cells.

Sex hormone-binding globulin (SHBG) was initially described as a plasma protein synthesized in, and secreted by, the liver. It was discovered by its ability to bind certain androgens and estrogens and, for many years, was believed to serve as a transporter/reservoir for the steroids which it bound. Subsequently, it became clear that the cell membranes of selected tissues contained a receptor for SHBG (R(SHBG)). This review deals with what is known of that receptor - its anatomy, physiology and biochemistry.

Human sex hormone-binding globulin gene expression- multiple promoters and complex alternative splicing.

BACKGROUND: Human sex hormone-binding globulin (SHBG) regulates free sex steroid concentrations in plasma and modulates rapid, membrane based steroid signaling. SHBG is encoded by an eight exon-long transcript whose expression is regulated by a downstream promoter (P(L)). The SHBG gene was previously shown to express a second major transcript of unknown function, derived from an upstream promoter (P(T)), and two minor transcripts. RESULTS: We report that transcriptional expression of the human SHBG gene is far more complex than previously described. P(L) and P(T) direct the expression of at least six independent transcripts each, resulting from alternative splicing of exons 4, 5, 6, and/or 7. We mapped two transcriptional start sites downstream of P(L) and P(T), and present evidence for a third SHBG gene promoter (P(N)) within the neighboring FXR2 gene; PN regulates the expression of at least seven independent SHBG gene transcripts, each possessing a novel, 164-nt first exon (1N). Transcriptional expression patterns were generated for human prostate, breast, testis, liver, and brain, and the LNCaP, MCF-7, and HepG2 cell lines. Each expresses the SHBG transcript, albeit in varying abundance. Alternative splicing was more pronounced in the cancer cell lines. P(L)- P(T)- and P(N)-derived transcripts were most abundant in liver, testis, and prostate, respectively. Initial findings reveal the existence of a smaller immunoreactive SHBG species in LNCaP, MCF-7, and HepG2 cells. CONCLUSION: These results extend our understanding of human SHBG gene transcription, and raise new and important questions regarding the role of novel alternatively spliced transcripts, their function in hormonally responsive tissues including the breast and prostate, and the role that aberrant SHBG gene expression may play in cancer.

Sex hormone-binding globulin influences gene expression of LNCaP and MCF-7 cells in response to androgen and estrogen treatment.

Sex hormone-binding globulin (SHBG), a plasma protein that binds androgens and estrogens, also participates in the initial steps of a membrane-based steroid signaling pathway in human prostate and breast. We have recently shown that SHBG is expressed at the mRNA and protein levels in the prostate and breast. In this study, we addressed whether locally expressed SHBG: (1) Functions to regulate activation of membrane-based steroid signaling and (2) influences activation of the androgen (AR) and estrogen (ER) receptors. Using microarray analysis, we identified specific genes that are influenced by SHBG expression in LNCaP and MCF-7 cells in a manner consistent with each of these properties. These findings suggest that locally expressed SHBG can play a functional role in the steroid responsiveness of prostate and breast cells through multiple signaling pathways and that perturbations in local SHBG expression could contribute to prostate and breast cancer.

Position statement: Utility, limitations, and pitfalls in measuring testosterone: an Endocrine Society position statement.

OBJECTIVE: The objective of the study was to evaluate the current state of clinical assays for total and free testosterone. PARTICIPANTS: The five participants were appointed by the Council of The Endocrine Society and charged with attaining the objective using published data and expert opinion. EVIDENCE: Data were gleaned from published sources via online databases (principally PubMed, Ovid MEDLINE, Google Scholar), the College of American Pathologists, and the clinical and laboratory experiences of the participants. CONSENSUS PROCESS: The statement was an effort of the committee and was reviewed in detail by each member. The Council of The Endocrine Society reviewed a late draft and made specific recommendations. CONCLUSIONS: Laboratory proficiency testing should be based on the ability to measure accurately and precisely samples containing known concentrations of testosterone, not only on agreement with others using the same method. When such standardization is in place, normative values for total and free testosterone should be established for both genders and children, taking into account the many variables that influence serum testosterone concentration.

Androgen therapy in women: an Endocrine Society Clinical Practice guideline.

OBJECTIVE: The objective was to provide guidelines for the therapeutic use of androgens in women. PARTICIPANTS: The Task Force was composed of a chair, selected by the Clinical Guidelines Subcommittee (CGS) of The Endocrine Society, six additional experts, a methodologist, and a medical writer. The Task Force received no corporate funding or remuneration. EVIDENCE: The Task Force used systematic reviews of available evidence to inform its key recommendations. The Task Force used consistent language and graphical descriptions of both the strength of recommendation and the quality of evidence, using the recommendations of the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) group. The strength of a recommendation is indicated by the number 1 (strong recommendation, associated with the phrase "we recommend") or 2 (weak recommendation, associated with the phrase "we suggest"). The quality of the evidence is indicated by cross-filled circles, such that [1 cross-filled circle, 3 empty circles] denotes very-low-quality evidence, [2 cross-filled circles, 2 empty circles] low quality, [3 cross-filled circles, 1 empty circle] moderate quality, and [4 cross-filled circles] high quality. Each recommendation is followed by a description of the evidence. CONSENSUS PROCESS: Consensus was guided by systematic reviews of evidence and discussions during one group meeting, several conference calls, and e-mail communications. The drafts prepared by the task force with the help of a medical writer were reviewed successively by The Endocrine Society's CGS, Clinical Affairs Committee (CAC), and Executive Committee. The version approved by the CGS and CAC was placed on The Endocrine Society's web site for comments by members. At each stage of review, the Task Force received written comments and incorporated needed changes. CONCLUSIONS: We recommend against making a diagnosis of androgen deficiency in women at present because of the lack of a well-defined clinical syndrome and normative data on total or free testosterone levels across the lifespan that can be used to define the disorder. Although there is evidence for short-term efficacy of testosterone in selected populations, such as surgically menopausal women, we recommend against the generalized use of testosterone by women because the indications are inadequate and evidence of safety in long-term studies is lacking. A review of the data currently available is presented, and areas of future research are outlined. To formulate clinical guidelines for use of testosterone in women, additional information will be necessary. This includes defining conditions that, when not treated with androgens, have adverse health consequences to women; defining clinical and laboratory parameters that distinguish those with these conditions; and assessing the efficacy and long-term safety of androgen administration on outcomes that are important to women diagnosed with these conditions. This necessary clinical research cannot occur until the biological, physiological, and psychological underpinnings of the role of androgens in women and candidate disorders are further elucidated.