Interaction between oral estrogen plus progestogen therapy and ABO blood groups on coagulation activation in postmenopausal women

Genome-wide Association Study of Estradiol Levels and the Causal Effect of Estradiol on Bone Mineral Density

CONTEXT

Estradiol is the primary female sex hormone and plays an important role for skeletal health in both sexes. Several enzymes are involved in estradiol metabolism, but few genome-wide association studies (GWAS) have been performed to characterize the genetic contribution to variation in estrogen levels.

OBJECTIVE

Identify genetic loci affecting estradiol levels and estimate causal effect of estradiol on bone mineral density (BMD).

DESIGN

We performed GWAS for estradiol in males (n = 147 690) and females (n = 163 985) from UK Biobank. Estradiol was analyzed as a binary phenotype above/below detection limit (175 pmol/L). We further estimated the causal effect of estradiol on BMD using Mendelian randomization.

RESULTS

We identified 14 independent loci associated (P < 5 × 10-8) with estradiol levels in males, of which 1 (CYP3A7) was genome-wide and 7 nominally (P < 0.05) significant in females. In addition, 1 female-specific locus was identified. Most loci contain functionally relevant genes that have not been discussed in relation to estradiol levels in previous GWAS (eg, SRD5A2, which encodes a steroid 5-alpha reductase that is involved in processing androgens, and UGT3A1 and UGT2B7, which encode enzymes likely to be involved in estradiol elimination). The allele that tags the O blood group at the ABO locus was associated with higher estradiol levels. We identified a causal effect of high estradiol levels on increased BMD in both males (P = 1.58 × 10-11) and females (P = 7.48 × 10-6).

CONCLUSION

Our findings further support the importance of the body's own estrogen to maintain skeletal health in males and in females.

Sex hormones and venous thromboembolism - from contraception to hormone replacement therapy

The use of sex hormones such as combined oral contraceptives (COC) or hormone replacement therapy (HRT) increases the risk for venous thromboembolism (VTE) considerably, especially in patients with an increased intrinsic risk for thromboembolic complications. Despite public and media attention and increasing scientific evidence, prescription patterns seem to be hard to change. It is well recognized that the patient's baseline risk is the most relevant factor in the absolute risk for developing VTE. The relative risk increase associated with sex hormones, depends on the type and dosage of hormones, the route of application (oral, vaginal, transdermal), and for COC, on the specific combination of oestrogen and gestagen components. Consequently, a careful decision for or against any specific type of hormone treatment needs to be based on an assessment of the patient's risk profile (disposition) as well as on the treatment-associated risks and benefits (exposition). This review discusses the most common sex hormone treatments in contraception and HRT, the relevance for VTE risk patients, and strategies to counsel patients with regard to hormone use according to their risk profiles. Keywords: Oral contraceptives, hormonal contraception, hormone replacement therapy, venous thromboembolism.

Prevention and treatment of venous thromboembolism during HRT: current perspectives

Many large trials in the past 15 years have proven an increased risk of vascular complications in women using oral, mostly non-bioidentical, hormone therapy. The risk of vascular complications depends on the route of administration (oral versus transdermal), age, duration of administration, and type of hormones (bioidentical versus non-bioidentical). Acquired and/or hereditary thrombophilias (eg, factor V Leiden, prothrombin mutation G20210A, and others) lead to a further increase of risk for venous thromboembolism, stroke, or myocardial infarction. Therefore, bioidentical hormone therapy via the transdermal route seems to be the safest opportunity for hormone replacement therapy, although large trials for bioidentical hormone therapy are needed.

ABO blood group polymorphisms and risk for ischemic stroke and peripheral arterial disease

Recent studies have demonstrated association between ABO blood system and thrombosis, indicating that individuals belonging to non-O blood groups (A, B or AB) present an increased risk of venous thrombosis, heart disease, and ischemic stroke (IS) as compared to O blood group carriers. In this study, we investigated the frequency of ABO blood group polymorphisms and its association with IS and peripheral arterial disease. Significant differences were observed for O1 (OR 0.57, 95% CI 0.35-0.95, p < 0.05) and O2 (OR 3.47, 95% CI 1.15-10.28, p < 0.05) alleles among IS patients while significant differences were observed for B phenotype (26.3 vs 9.5%, OR 3.42, 95% CI 1.32-8.76, p = 0.01, patients vs controls, respectively) and alleles A1 (OR 0.31, 95% CI 0.11-0.84, p < 0.05), O2 (OR 4.61, 95% CI 1.59-13.23, p < 0.01) and B (OR 3.42, 95% CI 1.62-7.13, p < 0.001) alleles for PAD patients. O1 allele was an independent variable (OR 0.27, 95% CI 0.12-0.57, p < 0.001) for IS patients. These data suggest the relationship of non-O blood groups in pathogenesis of thrombosis events and a possible protective effect of O blood group.

The risk of venous thrombosis in women over 50 years old using oral contraception or postmenopausal hormone therapy

BACKGROUND

Oral contraception (OC) and postmenopausal hormone therapy (HT) can be used to alleviate menopausal symptoms. However, the risk of venous thrombosis (VT) associated with OC use in women over 50 years old has never been assessed and the two preparations have not been directly compared.

OBJECTIVES

To determine and compare the risk of VT associated with OC and HT use.

METHODS

From a large case-control study, 2550 women aged over 50 years old, 1082 patients with a first VT and 1468 controls, were included. Odds ratios (ORs) and 95% confidence intervals for VT were calculated for OC-users (164 patients and 54 controls) and HT-users (88 patients and 102 controls) compared with non-hormone users (823 patients and 1304 controls).

RESULTS

OC-users had a 6.3-fold (4.6-9.8) increased risk of VT. This ranged from 5.4 (3.3-8.9) for preparations containing levonorgestrel to 10.2 (4.8-21.7) for desogestrel. The VT-risk associated with oral HT use was 4.0 (1.8-8.2) for conjugated equine estrogen combined with medroxyprogesterone acetate and 3.9 (1.5-10.7) for micronized estradiol combined with norethisterone acetate. Non-oral HT did not increase the risk of VT: OR 1.1 (0.6-1.8). Relative risk estimates were further increased in hormone users with factor V Leiden, prothrombin G20210A or blood group non-O and hormone users with a family history of VT.

CONCLUSIONS

In this study, non-oral HT seemed to be the safest hormonal preparation in women over 50 years old. OC use increased the VT risk the most, especially in women with inherited thrombophilia or a family history of VT.

Preeclampsia and ABO blood groups: a systematic review and meta-analysis

Preeclampsia (PE) is a multifactorial pregnancy-specific syndrome which represents one of the leading causes of maternal mortality worldwide. Inherited thrombophilia have been investigated as risk factor for the development of PE and it is currently known that ABO blood group may impact haemostatic balance, having the non-O blood groups (A, B or AB) subjects increased risk for thrombus formation, as compared to those of group O. We performed a systematic review of the literature for published studies investigating whether ABO blood groups could influence PE developing. A sensitive search of four databases identified 45 unique titles. The retrieved papers were assessed independently by authors and a rigorous process of selection and data extract was conduct. Methodological quality of the included studies was also evaluated. Two studies met eligibility criteria. As a main finding of our systematic review, an association between the AB blood group and the occurrence of PE was detected based on two original studies. Considering the role of ABO blood groups on the hemostatic process and thrombus formation, special attention should be given to pregnant patients carrying the AB blood group in order to prevent the syndrome and improve prognosis.