Role of ERα and Aromatase in Juvenile Gigantomastia.

CONTEXT: Approximately 150 patients with juvenile gigantomastia have been reported in the literature but the underlying biologic mechanisms remain unknown. OBJECTIVE: To conduct extensive clinical, biochemical, immunochemical, and genetic studies in 3 patients with juvenile gigantomastia to determine causative biologic factors. METHODS: We examined clinical effects of estrogen by blockading estrogen synthesis or its action. Breast tissue aromatase expression and activity were quantitated in 1 patient and 5 controls. Other biochemical markers, including estrogen receptor α (ERα), cyclin D1 and E, p-RB, p-MAPK, p-AKT, BCL-2, EGF-R, IGF-IR ß, and p-EGFR were assayed by Western blot. Immunohistochemical analyses for aromatase, ERα and ß, PgR, Ki67, sulfotransferase, estrone sulfatase, and 17ßHD were performed in all 3 patients. The entire genomes of the mother, father, and patient in the 3 families were sequenced. RESULTS: Blockade of estrogen synthesis or action in patients resulted in demonstrable clinical effects. Biochemical studies on fresh frozen tissue revealed no differences between patients and controls, presumably due to tissue dilution from the large proportion of stroma. However, immunohistochemical analysis of ductal breast cells in the 3 patients revealed a high percent of ERα (64.1% ± 7.8% vs reference women 9.6%, range 2.3-15%); aromatase score of 4 (76%-100% of cells positive vs 30.4% ± 5.6%); PgR (69.5% ± 15.2% vs 6.0%, range 2.7%-11.9%) and Ki67 (23.7% ± 0.54% vs 4.2%). Genetic studies were inconclusive although some intriguing variants were identified. CONCLUSION: The data implicate an important biologic role for ERα to increase tissue sensitivity to estrogen and aromatase to enhance local tissue production as biologic factors involved in juvenile gigantomastia.

Intensive, telemedicine-based, self-management program for rural, underserved patients with diabetes mellitus: Re-entry of retired endocrinologists into practice.

INTRODUCTION: Endocrinology workforce data demonstrate a substantial gap in the number of practicing endocrinologists, a phenomenon particularly affecting patients with diabetes in rural, financially challenged, underserved areas. We evaluated the concept that retired endocrinologists could re-enter practice part time and utilize telemedicine in collaboration with personnel in Federally Qualified Community Health Center clinics to conduct an intensive self-management program and provide 6-month concurrent care for patients with diabetes. METHODS: The program involved intensive glucose control measures and education in diabetes, nutrition, and lifestyle changes over a 6-month period. Key elements included comprehensive initial telehealth evaluations, frequent phone calls, and collaboration with certified diabetes care and education specialists, referring providers, referring-clinic staff, and the University of Virginia Telehealth Center. RESULTS: The mean A1C in the 139 patients completing the 6-month self-management program decreased from 10.3 ± 1.94% to 7.78 ± 1.51% p < 0.0001. The number of treatment modalities per patient ranged from one to five with several different regimens utilized. The majority of patients maintained the reduction in A1C levels without recidivism over a mean follow-up of 16 months after discharge. Strategies using meal replacements are being implemented to facilitate weight loss. DISCUSSION: This program resulted in improved A1C levels of patients with diabetes in rural, financially challenged, underserved areas; met recidivism goals; and provided a practical template to reduce the workforce gap of endocrinologists in those areas.

Mechanistic Effects of Estrogens on Breast Cancer.

PURPOSE: Current concepts regarding estrogen and its mechanistic effects on breast cancer in women are evolving. This article reviews studies that address estrogen-mediated breast cancer development, the prevalence of occult tumors at autopsy, and the natural history of breast cancer as predicted by a newly developed tumor kinetic model. METHODS: This article reviews previously published studies from the authors and articles pertinent to the data presented. RESULTS: We discuss the concepts of adaptive hypersensitivity that develops in response to long-term deprivation of estrogen and results in both increased cell proliferation and apoptosis. The effects of menopausal hormonal therapy on breast cancer in postmenopausal women are interpreted based on the tumor kinetic model. Studies of the administration of a tissue selective estrogen complex in vitro, in vivo, and in patients are described. We review the various clinical studies of breast cancer prevention with selective estrogen receptor modulators and aromatase inhibitors. Finally, the effects of the underlying risk of breast cancer on the effects of menopausal hormone therapy are outlined. DISCUSSION: The overall intent of this review is to present data supporting recent concepts, discuss pertinent literature, and critically examine areas of controversy.

Approach to the Patient With New-Onset Secondary Amenorrhea: Is This Primary Ovarian Insufficiency?

Menstrual cyclicity is a marker of health for reproductively mature women. Absent menses, or amenorrhea, is often the initial sign of pregnancy-an indication that the system is functioning appropriately and capable of generating the intended evolutionary outcome. Perturbations of menstrual regularity in the absence of pregnancy provide a marker for physiological or pathological disruption of this well-orchestrated process. New-onset amenorrhea with duration of 3 to 6 months should be promptly evaluated. Secondary amenorrhea can reflect structural or functional disturbances occurring from higher centers in the hypothalamus to the pituitary, the ovary, and finally, the uterus. Amenorrhea can also be a manifestation of systemic disorders resulting in compensatory inhibition of reproduction. Identifying the point of the breakdown is essential to restoring reproductive homeostasis to maintain future fertility and reestablish reproductive hormonal integrity. Among the most challenging disorders contributing to secondary amenorrhea is primary ovarian insufficiency (POI). This diagnosis stems from a number of possible etiologies, including autoimmune, genetic, metabolic, toxic, iatrogenic, and idiopathic, each with associated conditions and attendant medical concerns. The dual assaults of unanticipated compromised fertility concurrently with depletion of the normal reproductive hormonal milieu yield multiple management challenges. Fertility restoration is an area of active research, while optimal management of estrogen deficiency symptoms and the anticipated preventive benefits of hormone replacement for bone, cardiovascular, and neurocognitive health remain understudied. The state of the evidence for an optimal, individualized, clinical management approach to women with POI is discussed along with priorities for additional research in this population.

Approach to Managing a Postmenopausal Patient.

CASE AND PRINCIPLES OF MANAGEMENT: The case of a symptomatic, postmenopausal woman is presented and a full discussion of the approach to her management is discussed. Pertinent guidelines and scientific evidence are emphasized as support for the recommendations.

Workshop on normal reference ranges for estradiol in postmenopausal women, September 2019, Chicago, Illinois.

The North American Menopause Society (NAMS) organized the Workshop on Normal Ranges for Estradiol in Postmenopausal Women from September 23 to 24, 2019, in Chicago, Illinois. The aim of the workshop was to review existing analytical methodologies for measuring estradiol in postmenopausal women and to assess existing data and study cohorts of postmenopausal women for their suitability to establish normal postmenopausal ranges. The anticipated outcome of the workshop was to develop recommendations for establishing normal ranges generated with a standardized and certified assay that could be adopted by clinical and research communities. The attendees determined that the term reference range was a better descriptor than normal range for estradiol measurements in postmenopausal women. Twenty-eight speakers presented during the workshop.

Underlying Breast Cancer Risk and Menopausal Hormone Therapy.

The recent Collaborative Group on Hormonal Factors in Breast Cancer (CGHFBC) publication calculated the attributable risk of breast cancer from use of estrogen alone and estrogen plus a synthetic progestogen for less than 5 to 15 or more years of use. This CGHFB report calculated attributable risk based on their findings of relative risk from pooled data from 58 studies. Notably, neither the CGHFBC nor other previous studies have examined the effect of underlying risk of breast cancer on attributable risk. This omission prompted us to determine the magnitude of the effect of underlying risk on attributable risk in this perspective. Meaningful communication of the potential risk of menopausal hormonal therapy requires providing women with the estimated risk above their existing underlying risk (ie, attributable risk). Therefore, we have estimated attributable risks from the data published by the CGHFBC, taking into account varying degrees of underlying risk. Based on the Endocrine Society Guideline on Menopausal Hormone Therapy (MHT), we divided groups into 3 categories of risk: low (1.5%), intermediate (3.0%), and high (6.0%) underlying risk of breast cancer over 5 years. In women taking estrogen plus a synthetic progestogen for 5 to 9 years, the attributable risks of MHT increased from 12, to 42, to 85 additional women per 1000 in the low-, intermediate-, and high-risk groups, respectively. The attributable risks for estrogen alone were lower but also increased based on underlying risk. Notably, the attributable risks were amplified with duration of MHT use, which increased both relative risk and breast cancer incidence.

Systemic estradiol levels with low-dose vaginal estrogens.

OBJECTIVES: To critically evaluate published systemic estradiol levels during use of low-dose vaginal estrogens considering detection method and estrogen dose; describe challenges with accurately measuring estradiol; and determine the normal estradiol level range in postmenopausal women. METHODS: PubMed was searched for studies reporting systemic estradiol levels with lower-dose vaginal estrogens (≤25 µg estradiol or 0.3 mg conjugated equine estrogens). Estradiol levels at baseline and during treatment, area under the curve, and maximum estradiol concentrations were summarized by dose within assay type. A proposed range of systemic estradiol in normal, untreated, postmenopausal women was estimated by conservatively pooling means and standard deviations from published studies. RESULTS: Mean basal estradiol levels were 3.1 to 4.9 pg/mL using liquid or gas chromatography/mass spectroscopy (LC or GC/MS/MS) with a range of undetectable to 10.5 pg/mL using radioimmunoassay. Systemic estradiol levels with vaginal estrogens reflected their doses as measured with LC or GC/MS/MS in different studies: 7.1 to 9.1 pg/mL and 16.7 to 22.7 pg/mL with a 25-µg softgel capsule insert and a tablet insert, respectively; 4.6 to 7.4 pg/mL and 6.6 to 14.8 pg/mL with a 10-µg softgel capsule and a tablet insert, respectively; and 3.6 to 3.9 pg/mL with a 4-µg softgel capsule insert. A mean systemic estradiol concentration ranging from undetectable to 10.7 pg/mL is proposed as an estimate for basal estradiol levels in normal, untreated, postmenopausal women. Systemic estradiol absorption may be influenced by the placement of estradiol higher (as with an applicator) versus lower (as without an applicator) in the vagina, as estradiol transport to the uterus would be more likely further away than closer to the introitus. CONCLUSION: Serum estradiol concentrations were generally lower when measured with more specific and sensitive assays. Estradiol absorption was dose-dependent, and may be influenced by dose, formulation, and positioning in the vagina. Very low systemic estradiol absorption with low/ultralow-dose vaginal estrogens may potentially decrease any adverse events that may be associated with higher doses of vaginal estrogens used for treating moderate to severe VVA due to less estradiol exposure.

Pro-Apoptotic Effects of Estetrol on Long-Term Estrogen-Deprived Breast Cancer Cells and at Low Doses on Hormone-Sensitive Cells.

PURPOSE: Postmenopausal women with estrogen receptor-positive breast cancers often respond initially to tamoxifen or aromatase inhibitor therapy. Resistance to these treatments usually develops within 12 to 18 months. Clinical studies have demonstrated that high-dose estrogen can induce regression of these endocrine-resistant tumors. However, side-effects of high-dose estradiol (E2) or diethylstilbestrol (DES) limit their usage. Estetrol (E4) is the most abundant estrogen during pregnancy and has a long half-life and a low potential for side-effects. Estetrol might then provide benefits similar to DES on tumor regression but with lesser toxicity. METHODS: In this study, we systematically evaluated the effects of E4 on cell proliferation and apoptosis in wild-type MCF-7 and long-term estrogen-deprived (LTED) MCF-7 cells and compared its effects with E2 and estriol (E3). RESULTS: Estetrol induced apoptosis in LTED cells but stimulated growth of MCF-7 cells at concentrations from 10-11 to 10-8 M. These effects of E4 are similar to those of E2 but require much higher doses. Differing from E2, E4 at 10-12 M induced apoptosis in MCF-7 cells and another pregnancy estrogen, E3, acted similarly. No antagonistic effect of E4 or E3 against E2 occurred when they were combined. CONCLUSIONS: The pro-apoptotic effects of E4 and E3 on LTED cells and at low doses on MCF-7 cells indicate that these steroids could be used as therapeutic agents for endocrine-resistant or sensitive breast cancer.

Pituitary as a Source of HCG: Residual Levels After Bilateral Testicular Tumor Removal.

CONTEXT: Challenging clinical scenario in which elevated ß-human chorionic gonadotropin (HCG, subsequently termed HCG) levels suggested occult tumor metastases after removal of bilateral testicular cancers and metastases from them and as well as after chemotherapy. CASE REPORT: A 22-year-old male, post excision of bilateral testicular tumors, who had no imaging or clinical evidence of residual tumor but an elevated HCG raising the question of the presence and location of occult tumor metastases. Clinical Questions. Does luteinizing hormone (LH) cross-react with HCG in current assays? What levels of testosterone and estradiol are necessary to suppress LH and follicle-stimulating hormone (FSH) in a male patient with bilateral orchiectomy, and therefore lacking inhibin? Does the pituitary secrete HCG and under what circumstances? ASSESSMENT: Current HCG assays no longer cross-react with LH as did prior assays, but the presence of heterophile antibodies and other factors such as biotin can still cause false positive HCG levels. In the chronic post-orchiectomy state, the pituitary is relatively resistant to LH and FSH suppression by testosterone. The pituitary secretes HCG in very small amounts unless interruption of negative feedback results in high LH and FSH whereupon HCG levels become elevated. Clinical Conclusion. A GnRH antagonist suppressed both LH and HCG in this patient indicating that the elevated HCG was secreted by the pituitary and not by occult tumor metastases. Further credence for this conclusion resulted from the lack of a progressive increase in HCG levels over a 4-year period of follow-up and from no evidence of metastatic tumors on serial imaging.

Impact of route of administration on genotoxic oestrogens concentrations using oral vs transdermal oestradiol in girls with Turner syndrome.

OBJECTIVE: The established link between oestrogen and breast cancer occurs via both oestrogen receptor (ER)-mediated and non ER-mediated mechanisms. The term genotoxic estrogens describes mutagenic metabolites, including oestrogen catechols and quinones, which have been linked to breast carcinogenesis in post-menopausal women. We aimed to assess whether the route of administration of 17ß oestradiol (E2 ) affects the accumulation of genotoxic oestrogen metabolites in a model of ovarian failure in young girls with Turner syndrome. METHODS: Stored plasma samples obtained at 0 and 12 months were used from 40 adolescents with Turner syndrome who participated in a 12 months randomized controlled trial of the metabolic impact of E2 orally (2 mg/d) vs transdermally (100 µg/d); dose escalation allowed matching of unconjugated E2 levels in the parent study. We measured 12 oestrogen metabolites (total concentrations = conjugated and unconjugated) using a highly sensitive LCMSMS assay. Results from 48 normally menstruating adolescents were used for comparison. RESULTS: After treatment, least square mean (SE) total E2 concentrations were higher in the oral vs transdermal group (6784 pmol/L vs 1123 [1614], P < 0.0001), as was oestrone (E1 ) (91 060 pmol/L vs 19 278 [16 534], P < 0.0001). Also, higher after oral treatment were catechol-oestrogens 4-hydroxy-E2 (149 vs 28 [±49] pmol/L), 2-hydroxy-E2 (300 vs 76 [±52]), 4-hydroxy-E1 (450 vs 105 [±113]), 2-hydroxy-E1 (3094 vs 740 [±684]) and 16α-hydroxy-E1 (3,007 vs 157 [±534]) (<0.001 between groups). Levels were much closer to controls in the transdermal group. CONCLUSIONS: Common feminizing doses of oral oestradiol for 12 months result in substantial accumulation of unphysiologic, genotoxic oestrogens compared to transdermal oestradiol, expanding concerns about oral oestrogens' first hepatic passage. Further studies assessing long-term risks of these metabolites in women taking different forms of oestrogen are needed.

History of Estrogen: Its Purification, Structure, Synthesis, Biologic Actions, and Clinical Implications.

This mini-review summarizes key points from the Clark Sawin Memorial Lecture on the History of Estrogen delivered at Endo 2018 and focuses on the rationales and motivation leading to various discoveries and their clinical applications. During the classical period of antiquity, incisive clinical observations uncovered important findings; however, extensive anatomical dissections to solidify proof were generally lacking. Initiation of the experimental approach followed later, influenced by Claude Bernard's treatise "An Introduction to the Study of Experimental Medicine." With this approach, investigators began to explore the function of the ovaries and their "internal secretions" and, after intensive investigations for several years, purified various estrogens. Clinical therapies for hot flashes, osteoporosis, and dysmenorrhea were quickly developed and, later, methods of hormonal contraception. Sophisticated biochemical methods revealed the mechanisms of estrogen synthesis through the enzyme aromatase and, after discovery of the estrogen receptors, their specific biologic actions. Molecular techniques facilitated understanding of the specific transcriptional and translational events requiring estrogen. This body of knowledge led to methods to prevent and treat hormone-dependent neoplasms as well as a variety of other estrogen-related conditions. More recently, the role of estrogen in men was uncovered by prismatic examples of estrogen deficiency in male patients and by knockout of the estrogen receptor and aromatase in animals. As studies became more extensive, the effects of estrogen on nearly every organ were described. We conclude that the history of estrogen illustrates the role of intellectual reasoning, motivation, and serendipity in advancing knowledge about this important sex steroid.

Glucocorticoid Receptor Mutations and Hypersensitivity to Endogenous and Exogenous Glucocorticoids.

Background: The glucocorticoid receptor (GR) consists of two alternatively spliced isoforms: GRα, which activates gene transcription, and GRß, a dominant-negative receptor. Theoretically, inactivating variants of GRß could result in glucocorticoid hypersensitivity. Design: A 46-year-old woman presented for evaluation of adrenal insufficiency prompted by low plasma cortisol levels and multiple unexplained symptoms but without clinical evidence of glucocorticoid insufficiency. To explain these findings, extensive clinical, genetic, and molecular studies were performed. Methods: Standard clinical methods assessed the patient's hypothalamic-pituitary-adrenal axis. Validated molecular techniques were used for receptor sequencing, stable transfections, stimulation of candidate genes, cDNA arrays, Ingenuity Pathway Analysis, volcano analysis, and isolation and analysis of the patient's mononuclear cells. Results: Clinical studies excluded primary or secondary adrenal insufficiency, established consistently low basal cortisol levels, and demonstrated hypersensitivity to ultra-low-dose dexamethasone. Receptor sequencing identified two variants of GR9ß (A3669G and G3134T) as well as the known Bcl1 polymorphism. Reductionist studies using stable osteosarcoma cell lines transfected with the GRß variants demonstrated glucocorticoid hypersensitivity of transcribed genes on cDNA array analysis. The patient's monocytes responded to hydrocortisone with exaggerated stimulation of the candidate genes GILZ and FKBP5. Conclusion: Two variants of the dominant-negative GRß, in conjunction with a common Bcl1 intron variant, resulted in hypersensitivity to endogenous and exogenous glucocorticoids and, as a reflection of severity, low circulating cortisol levels without clinical evidence of glucocorticoid insufficiency. This prismatic case exemplifies the unique effects of variants of a dominant-negative receptor.

Effect of a tissue selective estrogen complex on breast cancer: Role of unique properties of conjugated equine estrogen.

The Women's Health Initiative studies reported that the menopausal hormone therapy (MHT) regimen containing conjugated equine estrogen (CEE) and medroxyprogesterone acetate increased, whereas CEE alone reduced breast cancer incidence. These observations suggest the possibility that CEE might exert unique actions on breast and also suggest the need to eliminate the progestogen from MHT regimens. A MHT regimen called a tissue selective estrogen complex (TSEC), containing CEE plus bazedoxifene (BZA), to avoid the need for a progestogen, was developed and FDA approved. Our study addressed two questions regarding this TSEC: (i) whether CEE exert effects on breast cancer which differ from those of estradiol (E2 ) and (ii) whether BZA antagonize the effects of E2 and CEE on breast cancer? Two rodent models (NMU and ACI) were used to compare the effect of CEE with E2 on mammary tumor formation, proliferation and apoptosis. In both the NMU and ACI models, E2 significantly increased tumor incidence and multiplicity whereas in striking contrast CEE did not, even though the estrogenic effects of CEE and E2 on uterine weight were identical. Mechanistically E2 blocked whereas CEE stimulated apoptosis (cleaved caspase-3) in ACI animals and only E2 stimulated proliferation (Ki67). BZA exerted highly potent anti-estrogenic effects on tumors by completely blocking palpable tumor formation. These data suggest that the CEE/BZA TSEC may be a safer, breast-antagonistic, MHT agent for women and might have potential to prevent breast cancer while relieving menopausal symptoms.

Estrogen Replacement in Turner Syndrome: Literature Review and Practical Considerations.

Context: Most girls with Turner syndrome (TS) have hypergonadotropic hypogonadism and need hormonal replacement for induction of puberty and then for maintaining secondary sex characteristics, attaining peak bone mass, and uterine growth. The optimal estrogen replacement regimen is still being studied. Evidence Acquisition: We conducted a systematic search of PubMed for studies related to TS and puberty. Evidence Synthesis: The goals of replacement are to mimic normal timing and progression of physical and social development while minimizing risks. Treatment should begin at age 11 to 12 years, with dose increases over 2 to 3 years. Initiation with low-dose estradiol (E2) is crucial to preserve growth potential. Delaying estrogen replacement may be deleterious to bone and uterine health. For adults who have undergone pubertal development, we suggest transdermal estrogen and oral progestin and discuss other approaches. We discuss linear growth, lipids, liver function, blood pressure, neurocognition, socialization, and bone and uterine health as related to hormonal replacement. Conclusion: Evidence supports the effectiveness of starting pubertal estrogen replacement with low-dose transdermal E2. When transdermal E2 is unavailable or the patient prefers, evidence supports use of oral micronized E2 or an intramuscular preparation. Only when these are unavailable should ethinyl E2 be prescribed. We recommend against the use of conjugated estrogens. Once progestin is added, many women prefer the ease of use of a pill containing both an estrogen and a progestin. The risks and benefits of different types of preparations, with examples, are discussed.

The Jewel in the Crown: Specific Aims Section of Investigator-Initiated Grant Proposals.

The specific aims section of National Institutes of Health and other grants is the most important component, as it summarizes the scientific premise, gap in current knowledge, hypotheses, methods, and expected results of the project proposed. The reviewer usually reads this section first and forms an immediate opinion, usually confirmed on reading the entire grant. This treatise reviews the philosophical background underlying generation of hypotheses, emphasizes the important characteristics of the specific aims section, and offers a point-by-point roadmap for writing. This perspective arose out of a new Endocrine Society initiative in which senior investigators review the specific aims of next-generation members.

Managing Menopausal Symptoms and Associated Clinical Issues in Breast Cancer Survivors.

Objective: Review evidence to guide management of menopausal signs and symptoms in women after breast cancer and make recommendations accordingly. Evidence: Randomized controlled clinical trials, observational studies, evidence-based guidelines, and expert opinion from professional societies. Background: Symptoms and clinical problems associated with estrogen depletion-sleep disorders, vulvovaginal atrophy (VVA), vasomotor symptoms (VMS), mood changes, depressive symptoms, cardiovascular disease, osteopenia, and osteoporosis-confront the estimated 9.3 million breast cancer survivors globally. Recommendations: Following breast cancer, women should not generally be treated with menopausal hormone therapy or tibolone but should optimize lifestyle. Women with moderate to severe symptoms may benefit from mind-brain behavior or nonhormone, pharmacologic therapy. The selective serotonin/noradrenaline reuptake inhibitors and gabapentenoid agents improve VMS and quality of life. For osteoporosis, nonhormonal agents are available. Treatment of VVA remains an area of unmet need. Low-dose vaginal estrogen is absorbed in small amounts with blood levels remaining within the normal postmenopausal range but could potentially stimulate occult breast cancer cells, and although poorly studied, is not generally advised, particularly for those on aromatase inhibitors. Intravaginal dehydroepiandrosterone and oral ospemiphene have been approved to treat dyspareunia, but safety after breast cancer has not been established. Vaginal laser therapy is being used for VVA but efficacy from sham-controlled studies is lacking. Therapies undergoing development include lasofoxifene, neurokinin B inhibitors, stellate ganglion blockade, vaginal testosterone, and estetrol. Conclusions: Nonhormone options and therapies are available for treatment of estrogen depletion symptoms and clinical problems after a diagnosis of breast cancer. Individualization of treatment is essential.

Use of cardiovascular age for assessing risks and benefits of menopausal hormone therapy.

The Women's Health Initiative studies and others have suggested that menopausal hormone therapy may enhance the risk of new cardiovascular (CV) events in older women and diminish the development of coronary atherosclerosis in younger women. The underlying mechanisms to explain these findings are encapsulated in the term "Timing Hypothesis." Extensive pathophysiologic studies have provided mechanistic evidence for the dichotomous effects of estrogen on coronary artery vasculature. Early in the atherosclerotic disease process, estrogen exerts protective effects on the endothelium and retards plaque formation. Late in the process, estrogen causes plaque erosion or rupture with subsequent thrombosis and acute coronary events. Analysis of the Timing Hypothesis in women examined in the Women's Health Initiative primarily used chronologic age to assess divergent effects of estrogen. The complexity of the data underlying coronary pathophysiology has resulted in controversy whether MHT can be used in older women or those with prior CV disease. In a debate of this issue at a recent International Menopause Society meeting, the concept of using CV age rather than chronologic age was discussed as a practical method of resolving this issue and facilitating therapeutic decisions in older women. This "Personal Perspective" will review the concepts underlying CV age, describe how it is determined, provide support for its utility, and propose future studies using this parameter.