Renal characteristics and effect of angiotensin suppression in oral contraceptive users

Physiological confounders of renal blood flow measurement

OBJECTIVES

Renal blood flow (RBF) is controlled by a number of physiological factors that can contribute to the variability of its measurement. The purpose of this review is to assess the changes in RBF in response to a wide range of physiological confounders and derive practical recommendations on patient preparation and interpretation of RBF measurements with MRI.

METHODS

A comprehensive search was conducted to include articles reporting on physiological variations of renal perfusion, blood and/or plasma flow in healthy humans.

RESULTS

A total of 24 potential confounders were identified from the literature search and categorized into non-modifiable and modifiable factors. The non-modifiable factors include variables related to the demographics of a population (e.g. age, sex, and race) which cannot be manipulated but should be considered when interpreting RBF values between subjects. The modifiable factors include different activities (e.g. food/fluid intake, exercise training and medication use) that can be standardized in the study design. For each of the modifiable factors, evidence-based recommendations are provided to control for them in an RBF-measurement.

CONCLUSION

Future studies aiming to measure RBF are encouraged to follow a rigorous study design, that takes into account these recommendations for controlling the factors that can influence RBF results.

A Holistic Framework for the Evaluation of Kidney Function in a Gender-Diverse Landscape

The most commonly used equations to estimate glomerular filtration rate incorporate a binary male-female sex coefficient, which has important implications for the care of transgender, gender-diverse, and nonbinary (TGD) people. Whether "sex assigned at birth" or a binary "gender identity" is most appropriate for the computation of estimated glomerular filtration rate (eGFR) is unknown. Furthermore, the use of gender-affirming hormone therapy (GAHT) for the development of physical changes to align TGD people with their affirmed gender is increasingly common, and may result in changes in serum creatinine and cystatin C, the biomarkers commonly used to estimate glomerular filtration rate. The paucity of current literature evaluating chronic kidney disease (CKD) prevalence and outcomes in TGD individuals on GAHT makes it difficult to assess any effects of GAHT on kidney function. Whether alterations in serum creatinine reflect changes in glomerular filtration rate or simply changes in muscle mass is unknown. Therefore, we propose a holistic framework to evaluate kidney function in TGD people. The framework focuses on kidney disease prevalence, risk factors, sex hormones, eGFR, other kidney function assessment tools, and the mitigation of health inequities in TGD people.

The effect of hormonal contraceptive therapy on clinical laboratory parameters: a literature review

Hormonal contraceptives (HC) are widely used among women in reproductive ages. In this review, the effects of HCs on 91 routine chemistry tests, metabolic tests, and tests for liver function, hemostatic system, renal function, hormones, vitamins and minerals were evaluated. Test parameters were differently affected by the dosage, duration, composition of HCs and route of administration. Most studies concerned the effects of combined oral contraceptives (COC) on the metabolic, hemostatic and (sex) steroids test results. Although the majority of the effects were minor, a major increase was seen in angiotensinogen levels (90-375 %) and the concentrations of the binding proteins (SHBG [∼200 %], CBG [∼100 %], TBG [∼90 %], VDBP [∼30 %], and IGFBPs [∼40 %]). Also, there were significant changes in levels of their bound molecules (testosterone, T3, T4, cortisol, vitamin D, IGF1 and GH). Data about the effects of all kinds of HCs on all test results are limited and sometimes inconclusive due to the large variety in HC, administration routes and dosages. Still, it can be concluded that HC use in women mainly stimulates the liver production of binding proteins. All biochemical test results of women using HC should be assessed carefully and unexpected test results should be further evaluated for both methodological and pre-analytical reasons. As HCs change over time, future studies are needed to learn more about the effects of other types, routes and combinations of HCs on clinical chemistry tests.

Oral Contraceptive Pills and Hypertension: A Review of Current Evidence and Recommendations

Oral contraceptive pills (OCPs) have been used as effective and popular forms of contraception since the middle of the last century. By 2019, over 150 million reproductive-aged individuals were using OCPs to prevent unintended pregnancies worldwide. Safety concerns regarding the effects of OCPs on blood pressure were reported soon after these pills gained approval. Although OCP doses were subsequently reduced, epidemiologic evidence continued to support a smaller, but significant association between OCPs and hypertension. Given the rising prevalence of hypertension, as well as the adverse effects of cumulative exposure to blood pressure elevations on cardiovascular disease risk, understanding the nature of the association between OCPs and hypertension is important for clinicians and patients to assess the risks and benefits of use, and make individualized decisions regarding contraception. Therefore, this review summarizes the current and historical evidence describing the association between OCP use and blood pressure elevations. Specifically, it identifies the pathophysiologic mechanisms linking OCPs to hypertension risk, describes the magnitude of the association between OCPs and blood pressure elevations, and distinguishes the effects of various OCP types on blood pressure. Finally, it describes current recommendations regarding hypertension and OCP use, as well as identifies strategies, such as over-the-counter OCP prescribing, to safely and equitably improve access to oral contraception.

Albumin, Oral Contraceptives, and Venous Thromboembolism Risk in Astronauts

BACKGROUND

A venous thromboembolism (VTE) event occurred in a female astronaut during long-duration spaceflight. Multiple factors may have contributed to this risk, including the use of combined (progestin + estrogen) oral contraceptives (cOC).

METHODS

Biochemistry data from 65 astronauts were evaluated for associations with cOC use and with sex.

RESULTS

The female astronauts who used cOCs had lower concentrations of serum albumin and higher concentrations of transferrin, a protein involved in the clotting cascade, than the male astronauts and the female astronauts who were not taking cOCs (P<0.001). The women who used cOCs had higher serum concentrations of the acute phase reactant ceruloplasmin during flight and cortisol (P<0.001) than the men and the women who were not taking cOCs; they also had higher calculated whole blood viscosity than women not taking cOCs (P<0.001).

CONCLUSIONS

Lower circulating concentrations of albumin, higher concentrations of transferrin, and elevated markers of inflammation all could contribute to an increased risk of VTE during spaceflight. These changes, in association with a higher blood viscosity can directly affect endothelial glycocalyx integrity and hypercoagulability status, both of which contribute to VTE risk in terrestrial populations.

A comparison between the effect of trans-anethole and metformin on biochemical parameters of polycystic ovary syndrome in rats

Objective:

The effect of trans-anethole and metformin on biochemical and hormonal changes of testosterone-induced Polycystic ovary syndrome (PCOS) in rats was investigated.

Materials and Methods:

Female Wister rats (n=48) were randomly divided into six groups: control; PCOS; PCOS+metformin (300 mg/kg); and PCOS+trans-anethole (20, 40, and 80 mg/kg). PCOS was induced by intraperitoneal injection of testosterone (1 mg/kg/day) for 35 days. After induction of PCOS, trans-anethole and metformin were given orally for 30 days. Finally, blood sugar, insulin, lipid profile, and testosterone and dehydroepiandrosterone (DHEAS) as well as animals’ weight, and water and food intake were determined.

Results:

In all treated and untreated PCOS groups, serum testosterone levels were significantly increased compared to the control group (p<0.001 for all groups). Treatment of rats with trans-anethole or metformin significantly reduced serum levels of cholesterol, insulin, triglycerides, testosterone and DHEAS (only in PCOS+trans-anethole groups) compared to the PCOS group (p<0.01-p<0.001). Weight gain in the PCOS animals increased significantly compared to the control group (p<0.001), while in the metformin- and trans-anethole (40 and 80)-treated animals it decreased significantly compared to the PCOS group (p<0.01-p<0.001).

Conclusion:

These results showed that trans-anethole significantly decreased serum levels of insulin, DHEAS and blood lipids. It can be concluded that trans-anethole ameliorates PCOS biochemical and hormonal change in PCOS rats; therefore, it might be suggested as a beneficial remedy for further clinical evaluations in PCOS patients.

Combined Oral Contraceptive Pill-Induced Hypertension and Hypertensive Disorders of Pregnancy: Shared Mechanisms and Clinical Similarities

PURPOSE OF REVIEW

Oral contraceptive pill-induced hypertension (OCPIH) and hypertensive disorders in pregnancy (HDP) share common risk factors and pathophysiological mechanisms, yet the bidirectional relationship between these two conditions is not well-established. We review and describe OCPIH and HDP to better understand how hormonal and metabolic imbalances affect hypertension.

RECENT FINDINGS

Oral contraceptive pills continue to be a popular method of contraception, with an incidence of OCPIH ranging from 1-8.5% among OCP users. HDP have an incidence of 5-10% of all pregnancies in the USA and have been shown to be a powerful predictor of lifetime adverse cardiovascular outcomes, including future hypertension. OCPIH and HDP share common risk factors such as age, BMI, past personal and family history of hypertension, as well as pathogenic mechanisms, including alterations in hormonal metabolism and the renin angiotensin aldosterone system; imbalance of vasodilator-vasoconstrictor compounds; and changes in the cardiovascular system. Future research should address additional potential mechanisms that underlie hypertension in these two conditions where endocrine changes, either physiological (pregnancy) or iatrogenic (use of OCP), play a role. This may lead to novel, targeted treatment options to improve hypertension management and overall cardiovascular risk profile management in this subset of young female patients.

Renal Failure among Women of Reproductive Age in Burundi: Estimating the Prevalence and Associated Factors Using Population-Based Data

Background

Renal failure is a leading cause of morbidity and mortality in many resource-constrained settings. In developing countries, little has been known about the prevalence and predisposing factors of renal failure using population-based data. The objective of this study was to examine the prevalence and associated factors of renal failure among women of reproductive age in Burundi.

Methods

We used nationally representative cross-sectional data from the 2016-2017 Burundi Demographic and Health Survey (BDHS). Data on 17,269 women of reproductive age were included. The outcome variable was a renal failure as determined by the patient's report. Percentage, chi-square test, and multivariable logistic regression model were used to analyze the data. The results from the logistic regression model were presented as adjusted odds ratio (AOR) and confidence interval (95% CI). The significance level was set at p < 0.05.

Results

The overall prevalence of renal failure was 5.0% (95% CI: 4.4%, 5.7%). Higher-aged women were more likely to have a renal failure when compared with women aged 15-19 years. Rural dwellers were 1.65 times as likely to have a renal failure when compared with women in the urban residence (AOR = 1.65; 95% CI: 1.24, 2.20). Women who had secondary + education had a 39% reduction in the odds of renal failure when compared with women with no formal education (AOR = 0.61; 95% CI: 0.46, 0.81). Health insurance coverage accounted for a 23% reduction in the odds of renal failure when compared with women who were not covered by health insurance (AOR = 0.77; 95% CI: 0.63, 0.93). Women who had a terminated pregnancy were 1.50 times as likely to have a renal failure when compared with women with no history of terminated pregnancy (AOR = 1.50; 95% CI: 1.24, 1.82). Furthermore, women with a history of contraceptive use were 1.32 times as likely to have a renal failure when compared with women without a history of contraceptive use (AOR = 1.32; 95% CI: 1.11, 1.57).

Conclusion

Lack of formal education, having no health insurance coverage, and ever used anything or tried to delay or avoid getting pregnant were the modifiable risk factors of renal failure. The nonmodifiable risk factors were old age, rural residence, certain geographical regions, and having a history of pregnancy termination. Understanding the risk factors of renal failure will help to instigate early screening, detection, and prompt treatment initiation. In addition, early detection of the risk factors can help to reduce the adverse health impact including maternal death.

Contraception in chronic kidney disease: a best practice position statement by the Kidney and Pregnancy Group of the Italian Society of Nephrology

Even though fertility is reduced, conception and delivery are possible in all stages of CKD. While successful planned pregnancies are increasing, an unwanted pregnancy may have long-lasting deleterious effects, hence the importance of birth control, an issue often disregarded in clinical practice. The evidence summarized in this position statement is mainly derived from the overall population, or other patient categories, in the lack of guidelines specifically addressed to CKD. Oestroprogestagents can be used in early, non-proteinuric CKD, excluding SLE and immunologic disorders, at high risk of thromboembolism and hypertension. Conversely, progestin only is generally safe and its main side effect is intramestrual spotting. Non-medicated intrauterine devices are a good alternative; their use needs to be carefully evaluated in patients at a high risk of pelvic infection, even though the degree of risk remains controversial. Barrier methods, relatively efficacious when correctly used, have few risks, and condoms are the only contraceptives that protect against sexually transmitted diseases. Surgical sterilization is rarely used also because of the risks surgery involves; it is not definitely contraindicated, and may be considered in selected cases. Emergency contraception with high-dose progestins or intrauterine devices is not contraindicated but should be avoided whenever possible, even if far preferable to abortion. Surgical abortion is invasive, but experience with medical abortion in CKD is still limited, especially in the late stages of the disease. In summary, personalized contraception is feasible, safe and should be offered to all CKD women of childbearing age who do not want to get pregnant.

Drug-Induced Hypertension

Untoward side effects of pharmaceuticals can result in considerable morbidity and expense to the health care system. There is likely a sizable fraction of the hypertensive population with disease either induced or exacerbated by polypharmacy. The elevation of blood pressure in drug-induced hypertension occurs through a variety of mechanisms, most notably, sodium and fluid retention, activation of the renin-angiotensin-aldosterone system, alteration of vascular tone, or a combination of these pathways. Recognition of common medications causing drug-induced hypertension is important to effectively control blood pressure. The epidemiology, pathophysiology, and management of these agents are discussed.

Older menarche age and short reproductive period linked to chronic kidney disease risk

This study aimed to investigate the association between reproductive period and menarche age and chronic kidney disease (CKD) in South Korean postmenopausal women.This was a cross-sectional study of the data for 8510 postmenopausal women using the results of Korean National Health and Nutrition Examination Surveys over the past 6 years.Of the total 8510 postmenopausal women, 790 (10.23%) were CKD patients. The menarche age in the CKD group was 16.2 ± 1.9 years old, which was higher than that in the non-CKD group (P < .001). The reproductive period of the CKD group was 32.4 ± 5.7 years, which was shorter than 33.3 ± 5.4 years in the non-CKD group (P < .001). The prevalence of CKD was 4.7% at a menarche age of 11 years or younger, which increased with increasing of menarche age, reaching 9.9% at menarche age of 16 years or older. According to the length of the reproductive period, the prevalence of CKD was 13.9% for the group less than 20 years of period and decreased significantly with increasing length of reproductive period. The prevalence of proteinuria was 7.2% in women with reproductive period of less than 20 years and significantly less in women with a reproductive period longer than 45 years (2.3%). The prevalence of CKD and proteinuria increased with increasing of menarche age, and the prevalence of CKD and proteinuria decreased with increasing of reproductive period.The results suggest that CKD was associated with older menarche age and a short reproductive period. Management of life patterns and medical problems in women with old age at menarche and a short reproductive period should be considered.

Fertility, Contraception, and Novel Reproductive Technologies in Chronic Kidney Disease

Chronic kidney disease (CKD) affects hypothalamic-pituitary-gonadal axis function, leading to menstrual abnormalities, sexual dysfunction, functional menopause, and loss of fertility. Pregnancy in a patient with CKD is associated with a higher risk of complications to both the mother and the fetus, highlighting the importance of contraceptive counseling at all stages of CKD. There has been limited research on the safety and efficacy of different contraceptive methods in the CKD population, and it is important to tailor the choice of contraception to the patient's lifestyle and comorbidity status. Cyclophosphamide is a commonly used immunosuppressive agent that impairs fertility in a dose-dependent fashion, with greater impact in older women of child-bearing age. Strategies to reduce the impact of cyclophosphamide on ovarian reserve as well as fertility preservation technologies are options to consider when treating immune-mediated CKD. A multidisciplinary approach in counseling the woman with CKD who wishes to contemplate or avoid pregnancy is necessary to optimize outcomes. Further research in this important area is required.

High salt intake does not aggravate glucose dysregulation and dyslipidemia induced by estrogen-progestin oral contraceptive

BACKGROUND

Estrogen-progestogen combined oral contraceptive (OC) use has been associated with increased cardiometabolic risk factors, including glucose dysregulation, dyslipidemia, hypertension, and pro-inflammatory state. However, the effect of a high-salt diet on these risk factors during OC use is not yet investigated. We therefore hypothesized that a high-salt diet would increase cardiometabolic risk factors in female rats treated with a combination of OC steroids, levonorgestrel (L) and ethinylestradiol (EE), and that elevated plasma levels of pro-inflammatory markers are associated with the cardiometabolic effects.

METHODS

Female Wistar rats were given (p.o.) vehicle, high-dose (1.0μg EE plus 5.0μgL) or low-dose (0.1μg EE plus 0.5μgL) OC with or without a high-salt diet (8%) daily for 8 weeks. Insulin resistance (IR) was estimated using the homeostatic model of assessment (HOMA).

RESULTS

Results showed that OC treatment or high salt diet led to significant increases in insulin resistance, plasma insulin, total cholesterol (TC), triglyceride (TG), TC/HDL-cholesterol, uric acid levels, and decreased glucose tolerance. OC treatment but not a high-salt diet resulted in increased plasma C-reactive protein and TG/HDL-cholesterol. However, a high-salt diet did not aggravate the effects of OC treatment.

CONCLUSION

The results from the present study indicate that glucose dysfunction and dyslipidemia induced by OC use, but not those induced by increased dietary salt are associated with elevated plasma C-reactive protein. Besides, increased dietary salt does not worsen abnormal cardiometabolic impact of OC use.

Combined oral contraceptive-induced hypertension is accompanied by endothelial dysfunction and upregulated intrarenal angiotensin II type 1 receptor gene expression

Combined oral contraceptive (COC) use is associated with increased risk of developing hypertension. Activation of the intrarenal renin-angiotensin system (RAS) and endothelial dysfunction play an important role in the development of hypertension. We tested the hypothesis that COC causes hypertension that is associated with endothelial dysfunction and upregulation of intrarenal angiotensin-converting enzyme 1 (Ace1) and angiotensin II type 1 receptor (At1r). Female Sprague-Dawley rats aged 12 weeks received (p.o.) olive oil (control) and a combination of 0.1 μg ethinylestradiol and 1.0 μg norgestrel (low COC) or 1.0 μg ethinylestradiol and 10.0 μg norgestrel (high COC) daily for 6 weeks. Blood pressure was recorded by tail cuff plethysmography. Expression of genes in kidney cortex was determined by quantitative real-time polymerase chain reaction. COC treatment led to increased blood pressure, circulating uric acid, C-reactive protein and plasminogen activator inhibitor-1, renal uric acid, and expression of renal Ace1 and At1r. COC treatment resulted in increased contractile responses to phenylephrine in endothelium-denuded aortic rings. Endothelium-dependent relaxation responses to acetylcholine, but not endothelium-independent relaxation responses to nitric oxide (NO) donation by sodium nitroprusside, were attenuated in COC-exposed rings. Impaired relaxation responses to acetylcholine were masked by the presence of NO synthase inhibitor (L-NAME) in the COC-exposed rings, whereas the responses to acetylcholine in the presence of selective cyclooxygenase-2 inhibitor (NS-398) were enhanced. These findings indicate that COC induces hypertension that is accompanied by endothelial dysfunction, upregulated intrarenal Ace1 and At1r expression, and elevated proinflammatory biomarkers.

Transdermal contraception and the renin-angiotensin-aldosterone system in premenopausal women

The oral contraceptive pill (OCP) activates the renin-angiotensin-aldosterone system (RAAS) through first-pass hepatic metabolism. Although usually benign, RAAS activation may have detrimental effects on renal and hemodynamic function in some women. Since combined hormonal contraception with the transdermal patch (EVRA) does not undergo first-pass hepatic metabolism, we hypothesized that the RAAS response would be different from that of OCP subjects. Thirty-five nonsmoking, premenopausal women (15 control subjects, 10 OCP subjects, and 10 contraceptive patch subjects) without evidence of cardiovascular disease, renal disease, or diabetes were studied. Baseline angiotensinogen, renin, angiotensin II, aldosterone, and plasma renin activity were assessed along with hormonal and hemodynamic responses to simulated orthostatic stress using incremental lower body negative pressure (LBNP; −15, −25, and −40 mmHg). Baseline levels of angiotensinogen, angiotensin II, and plasma renin activity were significantly higher in OCP subjects compared with normotensive control and contraceptive patch subjects ( P < 0.05), whereas aldosterone was significantly higher in OCP versus control subjects only ( P < 0.05). Plasma renin levels were significantly lower at baseline in contraceptive patch subjects compared with normotensive control and OCP subjects ( P < 0.05). In response to LBNP, increases in renin, angiotensin II, and aldosterone were attenuated in contraceptive patch subjects in conjunction with an exaggerated decline in mean arterial pressure ( P < 0.05 vs. control and OCP subjects). The contraceptive patch in healthy premenopausal women is associated with an impaired ability to maintain blood pressure in response to LBNP, possibly due to insensitivity of the endogenous RAAS. Further evaluation may be beneficial in women with kidney disease.

A single pill to treat postmenopausal hypertension? Not yet

Postmenopausal women make up one of the fastest growing populations in the United States. Women typically have a higher incidence of cardiovascular disease following menopause. One of the major risk factors for cardiovascular disease is hypertension, and after menopause, blood pressure (BP) increases progressively in women. Also after menopause, the progression of renal disease increases in women compared with aged matched men. However, the mechanism(s) responsible for the post-menopausal increase in BP and renal injury are yet to be elucidated. Moreover the best therapeutic options to treat postmenopausal hypertension in women are not clear. Hypertension in postmenopausal women are usually associated with other cardiovascular risk factors, such as dyslipidemias, visceral obesity and endothelial dysfunction. Recently it became apparent that in a large number of hypertensive postmenopausal women, their BP is not well controlled with conventional antihypertensive medications. A clear understanding of the complex pathogenesis of postmenopausal hypertension is needed in order to offer the best therapeutic options for these women.

Impact of bariatric surgery on comorbidities

Published data show that bariatric surgery not only leads to significant and sustained weight loss but also resolves or improves multiple comorbidities associated with morbid obesity. Evidence suggests that the earlier the intervention the better the resolution of comorbidities. Patients with metabolic syndrome and comorbidities associated with morbid obesity should be promptly referred for consideration for bariatric surgery earlier in the disease process.

Bariatric surgery and renal function

Obesity causes a significant healthcare burden and has been shown to be an important risk factor in the development of cardiovascular disease, type 2 diabetes, and increasingly chronic kidney disease. Bariatric surgery is the most effective treatment for obesity and has been shown to drastically improve both blood pressure and diabetic control. However, the interaction of bariatric surgery and renal function is less clear. This review focuses on the effect of bariatric surgery on renal function both in the acute situation, with respect to acute kidney injury, and also on changes in renal function parameters post-bariatric surgery weight loss. The interaction of obesity, bariatric surgery, and nephrolithiasis as a precipitant of acute kidney injury will also be considered. The role of bariatric surgery in pre- and post-renal transplant recipients is discussed as well as possible mechanisms underlying the improvement in renal function.

Blood pressure effects of the oral contraceptive and postmenopausal hormone therapies

Oral contraceptives and postmenopausal hormone therapy may induce hypertension through multiple mechanisms, including sodium and volume retention. Numerous studies have shown significant increases in blood pressure (BP) with the chronic administration of oral contraceptives as well as reversibility with discontinuation. The effects of different classes of oral contraceptive agents and hormonal replacement therapy on BP and associated effects on other cardiovascular risk factors are covered in this article. Novel hormonal replacement therapy that lowers BP is also discussed.

Dose-dependent toxic effects of high-dose estrogen on renal and cardiac injury in surgically postmenopausal mice

AIMS

We previously found that in mice with experimental myocardial infarction (MI), 17β-estradiol (E2) increased mortality and worsened cardiac remodeling and these deleterious effects were associated with renal enlargement and hydronephrosis in a dose-dependent manner. In the present study we questioned whether E2-induced renal damage predisposes to rather than results from its adverse effects on the heart.

MAIN METHODS

Ovariectomized (ovx) mice received either placebo (P) or E2 at 0.02 (E2-L, low dose), 0.42 (E2-M, moderate dose) or 4.2 μg/d (E2-H, high dose) for 8 weeks.

KEY FINDINGS

E2-L partially restored uterine weight and plasma estrogen levels without affecting heart, lung and liver weight, hemodynamic parameters, or heart and kidney morphology and function. E2-M restored normal uterine weight, but this was accompanied by a significant increase in kidney weight, albuminuria, glomerular matrix formation and markers for oxidative stress. E2-H increased uterine weight 4.5-fold and resulted in higher plasma creatinine levels, severe albuminuria, renal tubular dilatation, tubulointerstitial injury, hydronephrosis, glomerulosclerosis and oxidative stress. E2-H also caused ascites, hepatomegaly and fluid retention in the uterine horns but had no significant effect on blood pressure or heart function.

SIGNIFICANCE

Our data demonstrated that an excessive dose of E2 that raises uterine weight beyond physiological levels adversely affects the kidney even before it damages the heart. We believe estrogen dosage should be taken into account when considering hormonal replacement therapy, since inappropriate doses of E2 may damage not only the heart but also the kidney.

Dyslipidaemia, combined oral contraceptives use and their interaction on the risk of hypertension in Chinese women

The objective of the study was to assess the associations of dyslipidaemia, combined oral contraceptive (COC) use and their interaction on the risk of hypertension in Chinese women. In a case-control study, we evaluated 665 hypertensive women and 665 normotensive women matched on region and age in China. Hypertensive women had a higher prevalence of dyslipidaemia and higher levels of total cholesterol, triglyceride, low-density lipoprotein-cholesterol and lipoprotein a than normotensive ones (P<0.05). The risk of hypertension gradually increased with the increasing cumulative time of COC use in women (P=0.0043), especially significantly increased among those with cumulative time of COC use 15-20 and ≥20 years (adjusted odds ratio (OR)=1.46, 95% confidence interval (CI): 1.00-2.15; OR=1.49, 95% CI: 1.06-2.11), but gradually decreased from stopping use of COC (P<0.0001). The multiplicative interaction between dyslipidaemia and accumulative time of COC use ≥15 years, dyslipidaemia and family history of hypertension, or family history of hypertension and accumulative time of COC use ≥15 years was confirmed and the interaction analyses showed that they can significantly increased the risk of hypertension (adjusted OR=2.82, 95% CI: 1.59-3.27; OR=4.33, 95% CI: 3.10-6.06; OR=4.56, 95% CI: 3.07-6.77). It is concluded that dyslipidaemia, accumulative time of COC use ≥15 years and their interaction increased the risk of hypertension.

Oral contraceptive progestins and angiotensin-dependent control of the renal circulation in humans

Oral contraceptive (OC) use is associated with increased intra-renal renin-angiotensin-aldosterone system (RAA System) activity and risk of nephropathy, though the contribution of progestins contained in the OC in the regulation of angiotensin-dependent control of the renal circulation has not been elucidated. Eighteen OC users (8 non-diabetic, 10 Type 1 diabetic) were studied in high salt balance, a state of maximal RAA System suppression. Progestational and androgenic activity of the progestin in each OC was standardized to that of the reference progestin norethindrone. Renal plasma flow (RPF) was measured by paraaminohippurate clearance at baseline and in response to angiotensin converting enzyme (ACE)-inhibition. There was a positive correlation between OC progestational activity and the RPF response to ACE-inhibition (r=0.52, p=0.03). Similar results were noted with OC androgenic activity (r=0.54, p=0.02). On subgroup analysis, only non-diabetic subjects showed an association between progestational activity and angiotensin-dependent control of the renal circulation (r=0.71, p=0.05 non-diabetic; r=0.14, p=0.7 diabetic; p=0.07 between groups). Similar results were noted with respect to androgenic activity (r=0.88, p=0.005 non-diabetic; r=−0.33, p=0.3 diabetic; p=0.002 between groups). Our results suggest that the OC progestin component is a significant influence on the degree of angiotensin-dependent control of the renal circulation, though these findings may not apply to women with diabetes.

The bradykinin-degrading aminopeptidase P is increased in women taking the oral contraceptive pill

Introduction. The renin-angiotensin and kininogen-kinin hormonal systems are critically involved in regulating blood pressure and are candidates in contributing to oral contraceptive pill (OCP)-induced hypertension.Angiotensin-converting enzyme (ACE) and aminopeptidase P (AP-P) are key enzymes in these systems and are both involved in the degradation of the vasodilator bradykinin.

Methods. Circulating ACE and AP-P levels were measured by activity assay using selective fluorogenic peptide substrates in plasma samples from the Leeds Family Study. In addition, the effect of progesterone on the expression of AP-P and ACE was examined in cells.

Results. Women on the OCP had higher age-adjusted plasma AP-P (mean [95% confidence interval]) (0.27 [0.23-0.32] nmol/min/ml (n = 53)) compared with women not on the OCP (0.17 [0.16-0.19] nmol/min/ml (n = 133), p < 0.001) or males (0.19 [0.17-0.20] nmol/min/ml (n = 209), p<0.001).There were no differences in the age-adjusted plasma ACE levels among the three groups. In HepG2 cells, progesterone treatment increased the AP-P protein and mRNA expression, whereas no effect of progesterone treatment was observed for ACE.

Conclusion. Increased AP-P may result in increased breakdown of bradykinin.These data suggest that progesterone-induced increases in AP-P may contribute to the development of OCP-induced hypertension in susceptible Women.

The impact of hormonal contraceptives on blood pressure, urinary albumin excretion and glomerular filtration rate

AIM

In short-term studies, hormonal contraceptives (HC) have been suggested to induce a rise in blood pressure (BP) and urinary albumin excretion (UAE), while the effect of HC in renal function (GFR) is still under debate. Data on long-term and withdrawal effects of HC use on these outcomes are, however, not available. We therefore studied whether the start and cessation of HC induce changes in BP, UAE and GFR.

METHODS

We used data from the PREVEND Study, a prospective cohort of subjects aged 28-75 years. Eligible were women aged < or = 45 years with complete clinical and pharmacy data on baseline and follow-up screening (4 years later). Multivariate regression analysis was used to estimate the effects of HC on BP, UAE and GFR in those who started (n = 73), stopped (n = 117) or continued (n = 183) with those who never used HC (n = 286) as the reference group.

RESULTS

BP increased among starters and fell in stoppers. These changes compared with never-users were statistically significant, even after adjustment for relevant variables. UAE increased by 14.2% in starters (P = 0.074) and fell by 10.6% in stoppers (P = 0.021), while GFR fell by 6.3% in starters (P < 0.001) and did not change in stoppers. The effects of stopping HC on UAE and GFR were significantly different compared with changes among never-users, even after adjustment for other variables (P = 0.023 and 0.036, respectively).

CONCLUSIONS

The start of HC was independently associated with worsening of BP, UAE and GFR, while stopping HC use resulted in an improvement. These data suggest that long-term HC use (aged 28-45 years) may be deleterious from the cardiovascular and renal point of view, but stopping may result in correction of these effects.

Estradiol increases proteinuria and angiotensin II type 1 receptor in kidneys of rats receiving L-NAME and angiotensin II

Prospective, placebo-controlled clinical trials suggest that estrogen may have adverse effects on the vascular system in women. The goal of this study was to determine if 17beta-estradiol (E2) would have adverse effects on the renovasculature in a rat model of renal injury characterized by low nitric oxide (NO) and high angiotensin II (AngII). We studied female Wistar rats that were sham-operated (sham), ovariectomized (OVX), or ovariectomized and replaced with E2 (OVX/E2). All rats were maintained on a high salt diet and renovascular injury was caused by treating rats with an inhibitor of NO synthase, N(omega)-nitro-L-arginine-methyl-ester (L-NAME), for 14 days, plus AngII on days 11 through 14. L-NAME/AngII treatment, as compared to placebo, caused proteinuria, glomerular injury, and fibrinoid necrosis of renal arterioles in sham-operated rats. Ovariectomy reduced L-NAME/AngII-induced renal damage, whereas E2 treatment increased L-NAME/AngII-induced damage in OVX rats. In rats treated with L-NAME/AngII, levels of AngII type 1 receptor (AT(1)R) protein were higher in the renal cortex of sham and OVX/E2 rats than in OVX rats. AT(1)R protein correlated with renal injury. E2 treatment also increased expression of AT(1)R mRNA. Thus, under conditions of low NO and high AngII, E2 exacerbated renal injury. E2-mediated increases in renal cortical AT(1)R expression may represent a novel mechanism for the adverse renovascular effects of estrogen.

Estrogen and hypertension

Menopause is accompanied by a dramatic rise in the prevalence of hypertension in women, suggesting a protective role of endogenous estradiol on blood pressure (BP). Both animal experimental and human clinical investigations suggest that estrogen engages several mechanisms that protect against hypertension, such as activation of the vasodilator pathway mediated by nitric oxide and prostacyclin and inhibition of the vasoconstrictor pathway mediated by the sympathetic nervous system and angiotensin. However, emerging evidence from recent clinical trials indicates a small increase, rather than decrease, in systolic BP with oral estrogen administration in postmenopausal women, without any detectable effect on diastolic BP. Mechanisms underlying this selective rise in systolic BP in postmenopausal women and oral contraceptive-induced hypertension in premenopausal women remain unknown, but the rise may be related to supraphysiologic concentration of estrogen in the liver. To date, transdermal delivery of estrogen, which avoids the first-pass hepatic metabolism of estradiol, appears to have a small BP-lowering effect in postmenopausal women and may be a safer alternative in hypertensive women.

Oral contraceptives, angiotensin-dependent renal vasoconstriction, and risk of diabetic nephropathy

OBJECTIVE

Diabetes, the leading cause of end-stage renal disease in the U.S., is believed to involve activation of the renin angiotensin system (RAS) as a risk factor for nephropathy. RAS activation occurs in healthy women using oral contraceptives (OCs), but the effects of OC use on the diabetic kidney are unclear.

RESEARCH DESIGN AND METHODS

Renal plasma flow (RPF) response to captopril, as an index of RAS activity, was investigated in 92 women (41 nondiabetic OC nonusers, 10 nondiabetic OC users, 29 diabetic OC nonusers, and 12 diabetic OC users). Based on the hemodynamic findings, we examined the impact of OC use on the development of nephropathy as a post hoc analysis in an inception cohort of 114 female patients with newly diagnosed type 1 diabetes followed for a median of 20.7 years (range 1-24).

RESULTS

Nondiabetic OC nonusers showed minimal RPF vasodilator response to captopril (9 +/- 10 ml x min(-1) x 1.73 m(-2), P = 0.6). In comparison, nondiabetic OC users showed a significant increase (69 +/- 35 ml x min(-1) x 1.73 m(-2), P = 0.02) (P = 0.04 vs. nondiabetic OC nonusers). Diabetic OC nonusers demonstrated the anticipated vasodilator response (58 +/- 12 ml x min(-1) x 1.73 m(-2), P < 0.0001). Diabetic OC users showed the largest responses (84 +/- 12 ml x min(-1) x 1.73 m(-2), P = 0.002) (P = 0.04 vs. diabetic OC nonusers). Plasma renin activity did not vary with OC use (P = 0.3). The RPF responses to captopril and angiotensin receptor blocker were highly correlated (r = 0.72, P < 0.001), suggesting clear involvement of the RAS. In the observational study, 18% (6/33 [95% CI 4.3-32.1]) of OC users developed macroalbuminuria compared with 2% (2/81 [0-5.9]) of OC nonusers (P = 0.003, univariate analysis). After adjustment for known risk factors with a Cox regression model, OC use remained a predictor for the development of macroalbuminuria (relative risk 8.90 [95%CI 1.79-44.36], P = 0.008).

CONCLUSIONS

The strong association of OC use with angiotensin-dependent control of the renal circulation and the development of macroalbuminuria suggest that OC use may be a risk factor for diabetic nephropathy. Large prospective studies are required to further investigate this relationship.

Gender differences in hypertension and kidney disease

Gender differences exist in hypertension, the prevalence of several renal diseases, progression of established renal disease, and within the ESRD program, including renal transplantation. Sex hormones play key roles in the pathogenesis and outcome of disease processes. Observational data suggest gender differences in the prevalence and outcome of several renal diseases. The molecular mechanisms associated with physiologic phenomena needed to explain gender differences in renal disorders, however, remain largely obscure. The interaction of psychosocial, economic, medical, and genetic differences associated with discrepancies between the genders in the process of receiving a renal transplant and sustaining graft function are currently unclear. Additional studies are needed in these and other areas to explain gender differences in the incidence, prevalence, and outcome of renal disease.

From secondary to primary prevention of progressive renal disease: The case for screening for albuminuria

Many subjects nowadays present with end-stage renal failure and its attendant cardiovascular complications without known prior renal damage. In this report we review the evidence available to strongly suggest that the present practice of secondary prevention in those with known prior renal disease should be extended to primary prevention for those subjects in the general population who are at risk for progressive renal failure, but who had never suffered from a primary renal disease. We show that such subjects can be detected by screening for albuminuria. Elevated urinary albumin loss is an indicator not only of poor renal, but also of poor cardiovascular prognosis. In addition to diabetic subjects who are at risk for albuminuria, we also show that hypertensive, obese, and smoking subjects are more susceptible. We suggest that therapies that have been shown to lower albumin excretion, such as ACE inhibitors, angiotensin II receptor antagonists, and statins be started early in such patients to prevent them from developing clinical renal disease and its attendant cardiovascular complications.

Renal hemodynamic and tubular responses to salt in women using oral contraceptives

BACKGROUND

The use of oral contraceptives is associated with an increased risk of developing hypertension but the mechanisms of this hypertensive effect are not completely defined. The purpose of the present study was to assess prospectively the systemic and renal hemodynamic and tubular responses to salt in women taking oral contraceptives.

METHODS

Twenty seven young healthy normotensive women taking oral contraceptives containing monophasic combination of 30 microg ethynilestradiol and 150 microg desogestrel for>6 months were enrolled. All women were assigned at random to receive a low (40 mmol/day) or a high (250 mmol/day) sodium diet for 1 week on two consecutive menstrual cycles during the active oral contraceptive phase. At the end of each diet period, 24-hour ambulatory blood pressure, renal hemodynamics, sodium handling, and hormonal profile were measured.

RESULTS

The blood pressure response to salt on oral contraceptives was characterized by a salt-resistant pattern with a normal circadian rhythm. Salt loading results in an increase in glomerular filtration rate (GFR) (P < 0.05 vs. low salt), with no change in the renal plasma flow, thus leading to an increase in the filtration fraction (P < 0.05). At the tubular level, women on oral contraceptives responded to a low salt intake with a marked increased in proximal sodium conservation (P < 0.01 vs. high salt) and with an almost complete reabsorption of sodium reaching the distal tubule. After sodium loading, both the proximal and the distal reabsorption of sodium decreased significantly (P < 0.01).

CONCLUSION

The use of oral contraceptives is not associated with an increased blood pressure response to salt in young normotensive women. However, oral contraceptives affect the renal hemodynamic response to salt, a high salt intake leading to an increase in GFR and filtration fraction. This effect is possibly mediated by the estrogen-induced activation of the renin-angiotensin system. Oral contraceptives also appear to increase the tubular responsiveness to changes in sodium intake. Taken together, these data point out evidence that synthetic sex steroids have a significant impact on renal function in women. The renal effects of oral contraceptives should be taken into account when managing young women with renal diseases.

Cardiovascular risk factors are differently associated with urinary albumin excretion in men and women

Cardiovascular morbidity and mortality is not equally distributed among genders, men being more affected than women. It is not clear whether this is only related to a higher prevalence of the cardiovascular risk factors or to a similar prevalence of the risk factors as in women but a greater vascular susceptibility to these risk factors in men. This was tested by studying the association between various cardiovascular risk factors and urinary albumin excretion (UAE) in a large cohort of male and female subjects. While the prevalence of smoking and hypercholesterolemia was comparable between the genders, obesity was more common in women, and diabetes and hypertension were more frequent in men. The prevalence of microalbuminuria was about twofold higher in men. Interestingly, for a given level of any risk factor, UAE was higher in men than in women. On multivariate analysis with UAE as the dependent variable, an interaction with gender was found for the risk factors age, body mass index, and plasma glucose. Thus, for a higher age, body mass index, and glucose, the UAE is significantly increased in men when compared with women. It is concluded that gender differences exist in the association between cardiovascular risk factors and UAE. This is consistent with a larger vascular susceptibility to these risk factors in men as compared with women.

Drug-induced renal function impairment: a population-based survey

PURPOSE

The knowledge that drugs can affect renal function is mainly based on experimental studies or case reports. Thus, it has only been investigated in selected populations. Here we describe drug groups associated with altered renal function in the general population.

METHODS

To study this, we used baseline data of 8592 subjects of a population-based cohort. Hyper- and hypofiltration were defined as a filtration above or below the 90% confidence interval of age-and-sex-corrected creatinine clearance. Drug use was measured in the year preceding the kidney function measurement.

RESULTS

The prevalence of hyperfiltration (4.6% in the general population) was higher among subjects using anti-diabetics (11.7%), dermatological corticosteroids (5.9%) and sex hormones (5.8%), but lower in subjects using anti-thrombotics (2.4%) and diuretics (2.1%). Hypofiltration (4.3% in the general population) was seen more often in users of beta blockers (6.2%), ACE inhibitors (7.1%), statins (7.2%), anti-thrombitics (6.8%), trimethoprim (7.9%), vaccines (9.4%), NSAIDs (5.2%), anti-ulcer agents (6.3%), laxatives (7.7%) and eyedrops (6.7%).

CONCLUSIONS

Several drug groups found in this overview were to be expected, since patients with kidney disease often use them (e.g. cardiovascular drugs). Several other drug groups were somewhat unexpected and deserve further attention.

Hypertension, genotype and oral contraceptives

Oral contraceptive-induced hypertension (OCIH) is a well-recognized phenomenon characterized by an increase in blood pressure levels after beginning estroprogestin therapy and a reduction to normal levels within 1 year after suspension of the therapy. The pathophysiology of this condition is still not understood: several lines of evidence indicate a role for a genetic susceptibility to the development of this disease. In this article, the epidemiology and the pathogenesis of OCIH are reviewed with particular emphasis on the genetic influence in light of the most recent studies in this field.

Effect of oral contraceptives on the renin angiotensin system and renal function

We examined the effect of oral contraceptive (OC) usage on the renin angiotensin system (RAS) in two related experiments. In the first experiment, subjects were 34 healthy, normotensive, premenopausal women, 15 OC users and 19 OC nonusers, mean age 25 +/- 1 yr, ingesting a controlled sodium diet. We assessed arterial pressure, glomerular filtration rate, effective renal plasma flow, renal vascular resistance (RVR), and filtration fraction (FF) using inulin and p-aminohippurate clearance techniques, both at baseline and in response to the ANG II receptor blocker losartan. In the second experiment, in similar subjects, 10 OC users and 10 nonusers, we examined circulating RAS components [angiotensinogen, ANG II, aldosterone, plasma renin activity (PRA), and active renin] in response to incremental lower body negative pressure (LBNP), to determine whether renin secretion is suppressed by OC usage. OC users exhibited elevations in systolic blood pressure, RVR, and FF compared with nonusers, which were partially corrected by losartan. In the LBNP phase of the study, baseline measures of PRA, angiotensinogen, ANG II, and aldosterone were all increased in the OC group compared with the control group. Active renin levels did not differ between groups. Incremental LBNP resulted in increased circulating levels of RAS components in both groups. We conclude that the RAS is activated in women using OCs. There was no evidence that decreases in renin secretion result in normalization of the RAS as a whole.