Transforming growth factor-beta (TGF-beta) has been shown to inhibit the growth of mammary epithelial cells and may play a protective role in mammary carcinogenesis. In contrast, oestrogens promote the development of breast cancer. Oestrone sulphate (E1S) is a huge reservoir of active oestrogens in the breast being converted to the weak oestrogen, oestrone (E1), by oestrone sulphatase. E1 is reversibly converted by oestradiol-17beta hydroxysteroid dehydrogenase to the potent oestrogen, oestradiol (E2). The aim of this study was to assess the effect of the TGF-beta1 isoform on growth and oestrogen metabolism in the hormone-dependent MCF-7 and hormone-independent MDA-MB-231 human breast cancer cell lines. The results showed that TGF-beta1 significantly inhibited cell growth and stimulated the conversion of E1S to E1 and E1 to E2 in the MCF-7 cell line. In the MDA-MB-231 cell line TGF-beta1 significantly stimulated cell growth and inhibited the interconversions between E1 and E2. In conclusion, the growth inhibitory effect of TGF-beta1 on the MCF-7 cell line would appear to confer a protective effect in breast cancer. However, its ability to increase the amount of E2 would increase the risk of breast cancer. Which of these effects predominates in vivo remains to be explored. The growth stimulatory effect of TGF-beta1 on the MDA-MB-231 cell line probably acts through a mechanism independent of the effect of TGF-beta1 on oestrogen concentrations since this cell line is hormone unresponsive.

To test the hypothesis of an increased activity of the enzyme aromatase in adipose tissue from affected when compared with non-affected quadrants of patients with breast cancer, the aromatase activity has been measured in tumour and fatty tissues dissected at specific sites from the breasts of 16 patients. Activity was measured after extensive purification of the product formed. Results, expressed in fmol/g of tissue, did not show a higher activity in the affected vs the non-affected quadrants. In the tumours, higher activities were found when expressed per g of tissue. Per mg of DNA, an indicator of the number of cells, tumour enzymatic activity was lower than in fatty tissues. The relations between the products of aromatase, oestrone and oestradiol in the various tissues point to the importance of additional enzymatic processes, especially of the reductive 17 beta-oestradiol dehydrogenase, in the accumulation of high quantities of oestradiol in the malignant tissue.

OBJECTIVE

Oestetrol (15-alpha-hydroxyoestriol, E₄) is an endogenous oestradiol metabolite mainly produced at high concentrations in the fetal liver. In earlier studies E₄ was investigated for its use as marker for pregnancies at risk, especially with vascular problems. Some current investigations suggest that the use of E4 in hormone therapy or contraception may have advantages in terms of breast cancer risk when compared to other oestrogens.

METHODS

Proliferation of two oestrogen receptor-positive breast cancer cell lines (ZR 75-1 and HCC 1500) was investigated after incubation with oestrone (E₁), oestradiol (E₂), oestriol (E₃), and oestetrol (E₄). Receptor expression of oestrogen receptor-alpha (ERα) and -beta (ERβ) was determined by Western-Blot.

RESULTS

All four oestrogens elicited a significant proliferative stimulation at concentrations of 10(-10) und 10(-9) M as compared to controls. Oestrone displayed a significantly weaker effect than E₂. Oestetrol was significantly less effective than E₂ at the lower concentration. Expression of ERα and ERβ was significantly upregulated by all oestrogens tested, without differences between the latter.

CONCLUSIONS

Our results indicate a slightly lower proliferative effect of E₄, but only at low concentrations. However, no difference was found regarding receptor expression. Breast cancer risk associated with use of oestetrol should be tested in clinical trials.

17ss-Hydroxysteroid dehydrogenases (17HSDs) are involved in the local regulation of sex steroids. 17HSD1 converts oestrone (E1) to the more potent oestradiol (E2) and 17HSD2 catalyses the reverse reaction. The aim of this study was to investigate the expression of these enzymes in premenopausal breast cancers and to analyse if they have any prognostic or tamoxifen predictive value. Premenopausal patients with invasive breast cancer, stage II (UICC), were randomised to either 2years of adjuvant tamoxifen (n=276) or no tamoxifen (n=288). The median follow-up was 13.9years (range 10.5-17.5). The expression of 17HSD1 and 17HSD2 was analysed with immunohistochemistry using tissue microarrays. The enzyme expression level (-/+/++/+++) was successfully determined in 396 and 373 tumours, respectively. Women with hormone-receptor positive tumours, with low levels (-/+/++) of 17HSD1, had a 43% reduced risk of recurrence, when treated with tamoxifen (Hazard Ratio (HR)=0.57; 95% confidence interval (CI), 0.37-0.86; p=0.0086). On the other hand high expression (+++) of 17HSD1 was associated with no significant difference between the two treatment arms (HR=0.91; 95% CI, 0.43-1.95; p=0.82). The interaction between 17HSD1 and tamoxifen was significant during the first 5 years of follow-up (p=0.023). In the cohort of systemically untreated patients no prognostic importance was observed for 17HSD1. We found no predictive or prognostic value for 17HSD2. This is the first report of 17HSD1 in a cohort of premenopausal women with breast cancer randomised to tamoxifen. Our data suggest that 17HSD1 might be a predictive factor in this group of patients.

Oestradiol 17 beta-hydroxysteroid dehydrogenase (E2DH) is present in normal and malignant breast tissues and regulates the interconversion of oestrone and the biologically active oestrogen, oestradiol. Studies we have previously carried out have indicated that concentrations of oestradiol and the conversion of oestrone to oestradiol are higher in breast tumours than in normal breast tissues. We are currently isolating and characterizing factors produced by breast tumours which are capable of stimulating E2DH (reductive) activity. The production of such factors by breast tumours, which stimulate the conversion of oestrone to oestradiol, would provide a favourable oestrogenic environment to promote tumour growth and may account for the increased concentrations of oestradiol in breast tumours.

The effect of tamoxifen on the vaginal mucosa and on serum oestrone, oestradiol and gonadotrophin concentrations was investigated in a group of nine postmenopausal women with non-metastatic breast cancer. Compared with fit age-matched controls, the vaginal pH in the tamoxifen-treated group was significantly lower and was comparable to levels in fertile women. Two thirds of tamoxifen-treated women had well oestrogenized vaginal smears compared with none in the control group. Follicle-stimulating hormone was significantly reduced, whilst oestrone and oestradiol levels remained unchanged. We conclude, therefore, that tamoxifen has oestrogen-agonistic properties particularly evident in postmenopausal women, even though it is primarily an antioestrogenic drug.

The 17 beta-hydroxysteroid dehydrogenases (17 beta HSDs) play an important role in the regulation of intracellular levels of biologically active sex steroid hormones in various human tissues. To date, eight distinctive 17 beta HSD enzymes have been cloned and characterized in humans. Among these isoenzymes, 17 beta HSD type 2 (17 beta HSD2) catalyses the conversion of testosterone into androstenedione and/or oestradiol into oestrone in various tissues, and it has thus been suggested to be involved in the biological inactivation of these sex steroids. The human gastrointestinal tract and liver are considered as the principle sites of inactivation and metabolism of various forms of orally administered sex steroids. We therefore examined 17 beta HSD2 expression and activity in human adult non-pathological gastrointestinal tract in order to clarify further the biological significance of this enzyme. A total of 80 specimens (40 from males and 40 from females) of normal oesophageal, stomach, duodenal, ileal, colonic and rectal tissues were examined for immunohistochemistry. Altogether, 17 tissue specimens were used for enzyme assay, and eight for RNA analysis. 17 beta HSD2 activity was detected in the stomach, duodenum, ileum, colon and rectum. 17 beta HSD2 mRNA was most abundant in the small intestine. 17 beta HSD2 immunoreactivity was localized almost exclusively to the absorptive epithelium, which may be involved in the inactivation of excessive endogenous and exogenous active sex steroids. Results from the present study thus suggest that the human gastrointestinal tract is an important sex steroid metabolizing organ in humans.

A variety of organic compounds have been documented to bind to the oestrogen receptor and induce oestrogenic effects in different vertebrates. The presence of these environmental oestrogens or oestrogen mimics in the aquatic environment has been suspected of disrupting the normal endocrinology of wild populations of fish. In this study, induction of vitellogenin synthesis in primary hepatocytes from Atlantic salmon (Salmo salar) was optimized and validated as an oestrogenic in vitro bioassay using a sensitive capture vitellogenin enzyme-linked immunosorbent assay. After proper optimization (cell media supplements, cell density, temperature and exposure time), this assay gave a sensitive and reproducible response to both endogenous steroids (relative potency: 17beta-oestradiol>)oestriol>oestrone)17alpha-oestradiol) and a range of common oestrogen mimics (relative potency: ethynyloestradiol and diethylstilboestrol>)genistein and zearalenone>)bisphenol A and 4-t-octylphenol>4-n-nonylphenol and 2'-chloro,4-chloro-diphenyltrichloroethane (o,p'-DDT). However, the androgen testosterone and the putative oestrogen mimics dieldrin and toxaphene were not shown to be oestrogenic using this hepatocyte bioassay. Oestrogen-induced vitellogenin synthesis was efficiently inhibited by the anti-oestrogen ZM 189.154, suggesting that this bioassay may be used for testing both the oestrogenic and the anti-oestrogenic properties of chemicals.

Hepatic UDP-glucuronyltransferase activity was resolved into two fractions, one exhibiting oestrone glucuronyltransferase activity and the other exhibiting p-nitrophenol glucuronyltransferase activity. Hydroxyapatite-column chromatography removed greater than 95% of the phospholipids from both preparations. The partially purified delipidated enzymes were essentially devoid of catalytic activity, but activities were restored by the addition of phospholipids or phosphatidylcholine mixtures containing various saturated and unsaturated fatty acids. Both oestrone and p-nitrophenol glucuronyl-transferase activities were reconstituted to similar degrees with the phosphatidylcholine mixtures. When purified phospholipids were tested, phosphatidylcholine and lysophosphatidylcholine were most effective in restoring activity, whereas phosphatidylethanolamine was the least effective. These results further suggest that oestrone and p-nitrophenol UDP-glucuronyltransferases are dependent on phospholipids for their activity.

The components of heterosexual behaviour in rams are reviewed as a basis for understanding partner preference behaviour. A small percentage of rams will not mate with oestrous females and if given a choice will display courtship behaviour towards another ram in preference to a female. Some of the endocrine profiles of these male-oriented rams differ from those of heterosexual controls. These differences include reduced serum concentrations of testosterone, oestradiol and oestrone, reduced capacity to produce testosterone in vitro, and reduced capacity to aromatize androgens in the preoptic-anterior hypothalamus of the brain. Our observation that aromatase activity is significantly lower in the preoptic-anterior hypothalamic area of male-oriented rams than in female-oriented rams may indicate an important neurochemical link to sexual behaviour that should be investigated. The defect in steroid hormone production by the adult testes of the male-oriented ram may represent a defect that can be traced to the fetal testes. If this contention is correct, partner preference behaviour of rams may also be traceable to fetal development and represent a phenomenon of sexual differentiation.

1. An enzyme system that catalyses the sulphation of p-nitrophenol, cholesterol, alpha-ecdysone, beta-sitosterol, dehydroepiandrosterone, oestrone and four other steroids of plant and insect origin was obtained from the soluble fraction of southern-armyworm gut tissues. 2. The enzyme system required ATP and inorganic sulphate, and activity was slightly enhanced in the presence of GSH. 3. The properties of this enzyme system with respect to pH, temperature, substrate and protein concentrations and various cofactors and reagents were studied. At -23 degrees C the enzyme preparation could be stored for 2 weeks without drastic loss of activity. At the end of storage for 1 month the loss of activity was approx. 21%. 4. The possible involvement of this enzyme system in insect endocrine control is discussed.

In the present study the influence of oestradiol, catechol oestrogens, and O-methylated oestrogens was determined on the contractile responses of the isolated rabbit aorta to (-)-adrenaline. Oestradiol (40 mumol/l), 2-hydroxyoestradiol (2OHE2) (20 mumol/l), and 2-methoxyoestradiol (2MeOE2) (20 mumol/l) all sensitized the rabbit aorta to contractile responses to (-)-adrenaline. Similarly, the 2-hydroxy and 2-methoxy derivatives of oestrone and oestriol also sensitized the aorta to (-)-adrenaline-induced contractions. The largest degree of sensitization was seen in the presence of the 2-methoxysteroids. Oestradiol and 2OHE2 did not increase responses of the aorta to (-)-noradrenaline, while slight potentiation of contraction was seen in the presence of 2MeOE3. The potentiating effect of 2OHE2 on contractile responses to (-)-adrenaline was abolished by prior treatment of the tissue with a COMT inhibitor (U-0521, 55 mumol/l). Conversely, pretreatment of the tissue with 2OHE2 prevented the augmented aortic contraction to (-)-adrenaline usually seen after inhibition of COMT. The non-additive nature of the sensitization seen after combined treatment with 2OHE2 and U-0521 was qualitatively similar to that seen following combined exposure to maximally effective concentrations of U-0521 and an inhibitor of extraneuronal uptake (hydrocortisone 100 mumol/l). Oestradiol and 2MeOE2 reduced the formation of both the 3H-O-methylated, 3H-deaminated and the 3H-O-methylated deaminated metabolites of 3H-(-)-adrenaline (0.15 mumol/l) during exposure of the aorta to the tritiated catecholamine.(ABSTRACT TRUNCATED AT 250 WORDS)

Using infusions of [3H]dehydroepiandrosterone (DHEA) and [14C]oestrogens, the metabolic clearance rates (MCRD) and blood production rates (PDB) of DHEA and the rate of aromatization of DHEA to oestrone and oestradiol were measured in 7 normal post-menopausal women. The mean +/- SEM value for MCRD was 1850 +/- 270 l/day and for PDB was 3.2 +/- 0.6 mg/day. The MCRD value is similar to those reported for young women but PDB is less than those reported for younger women. The mean +/- SEM value for the aromatization rate of DHEA to E1 in 6 women was 0.0058 +/- 0.004 and in 1 woman the aromatization rate of DHEA to E2 was 0.0008. About 30% of the aromatization of DHEA to E1 occurred via the blood pool of androstenedione. However, 20-25% of E1 arose via the aromatization of DHEA to E1 in peripheral tissues without the intermediacy of the blood pool of androstenedione, and thus the peripheral aromatization of DHEA can be an important source of E1 in some women.

Circulating levels of oestrone, oestradiol and androstenedione were measured in two large groups of postmenopausal women, in one group the women were between 46 and 56 years of age and in the second, older group they were 70 years of age. In addition the fat mass was calculated from the height, weight and age of the women. Serum concentrations of both oestrogens did not change with age, whereas the serum androstenedione concentration decreased significantly. A change in body composition included decreased height and increased fat mass in the older group. Serum concentrations of both oestrogens correlated significantly with the fat mass and serum androstenedione as well as with each other. From the correlation analysis it may be concluded that the conversion rate of androstenedione to oestrone, and of oestrone to oestradiol, increases with age, which presumably explains the unchanged concentrations of the circulating oestrogens in relation to postmenopausal age, although the precursor decreases during the same period.

To study the relation between body weight and height and the plasma sex-hormone levels wer measured the plasma levels of oestrone (E1), oestradiol (E2) and androstenedione (A) in a group of healthy post-menopausal women with a wide range of body weight. The sex hormones were measured by radioimmunoassay with highly specific antisera after purification of the plasma extract by column chromatography. Our findings show that there is significant positive correlation between the E1 level and body weight as well as A level and, to a lesser extent, between the E1 level and Quetelet index. For E2 there is no correlation with these parameters. There is also a very slight correlation between A level, body weight and Quetelet index. Calculation of the partial correlation coefficient shows that E1 correlates to the same degree with body weight and A level, whereas the A level does not correlate with body weight at a fixed value for the E1 level. We conclude that variation in the E1 level depends to the same degree on the variation in body weight as well as the variation in A level.

The concentrations of progesterone, androstenedione, testosterone, oestrone and oestradiol were measured by radioimmunoassay in blastocysts and uterine fluid flushings collected from rabbits 110 to 159 h post coitum (p.c.). None of the blastocysts or uterine flushings contained detectable levels of androstenedione, testosterone or oestrone. All uterine flushings contained large amounts of progesterone and some of the flushings also contained oestradiol. A small amount of progesterone (approximately 7-5 pg/blastocyst) was first detectable in some blastocysts at 135 h p.c.; progesterone levels/blastocyst then increased progressively, reaching levels of about 122-158 pg/blastocyst at 159 h p.c. Micropuncture of blastocysts at 159 h p.c. indicated that greater than or equal to 90% of the progesterone in the embryo was in the blastocoelic fluid. Blastocysts from rabbit uterine horns containing oestradiol also contained oestradiol but those in which oestradiol was detected were never observed in uteri lacking the hormone. It is inferred that rabbit blastocysts accumulate both progesterone and oestradiol from uterine fluid.

Day-of-admission sera from myocardial infarction patients (MI) and patients with cardiopathies other than MI (non-MI) were analysed for total and unbound cortisol (F), progesterone (P4), oestrone (E1), and corticosteroid binding activities (CBG). The MI who survived (n = 28) showed high increases of F, P4 and E1 compared to healthy controls. By contrast, the MI who died within 10 days of admission (n = 6) had unchanged F and less increased P4 and E1 than survivors. The non-MI (n = 6) had higher F and E1 than controls but normal P4. The unbound steroids were increased in all patients: however, the MI who died showed much smaller rises than survivors (P less than 0.001 for unbound F and E1 increases in survivors vs. deceased). The CBG activity was in all MI lower than in normals (P less than 0.001) but unchanged in non-MI. These results are discussed in terms of the potential significance of unbound plasma steroids as predictors of MI severity.

Radioimmunological methods have been employed for the simultaneous determination of dehydroepiandrosterone, androstenedione, testosterone, oestrogens (oestradiol + oestrone), progesterone, 17 alpha-hydroxyprogesterone and cortisol in human adipose tissue and peripheral blood to compare the hormone pool of adipose tissue with that in the general circulation. Extremely high steroid concentrations in the adipose tissue and hormone pool in the fat of obese subjects were observed. For adipose tissue/serum steroid ratios, the highest values were obtained for dehydroepiandrosterone and the lowest ones for cortisol. A preliminary study showed a great accumulation of steroids in adjacent adipose tissue of breast tumors. Striking differences were observed in the adipose tissue steroid concentrations between benign and malignant mammary tumors. The present findings revealed that blood hormone determinations may be insufficient to consider the steroid hormone availability in various endocrinopathies or steroid responsive tumors, especially when the endocrine state of extremely obese subjects is observed.

The effects of oestradiol (Oe2), oestrone (Oe1), oestriol (Oe3), oestetrol (Oe4) on the induction of the progesterone receptor (PgR) and growth of MCF-7 cells are compared. All the four oestrogens increased cell PgR concentration. Analysis of the dose-response curves shows induction by Oe2 to be 10 times and 50 times greater than Oe3 and Oe4, respectively. Oe1 and Oe2 are equally effective, even with consideration of metabolic conversion of O31 into Oe2. When compared with untreated cells, Oe2, Oe3, and Oe4 do not influence significantly the plating efficiency but all 3 hormones increase thymidine incorporation of the cells in log phase growth. Oe2, Oe3 and Oe4 are able to rescue the growth inhibition induced by antioestrogens. The respective potency compared to Oe2 is again in the range of 10 and 50 times lower for Oe3 and Oe4, respectively. On the other hand Oe1 decreases plating efficiency, thymidine incorporation and does not rescue the growth inhibition induced by antioestrogens when the metabolic conversion of Oe1 into Oe2 is prevented. Thus, Oe3 and Oe4 behave like complete Oe2 agonists whereas Oe1 has dissociated effects, agonist on PgR induction and antagonist on cell growth.

Using constant infusions of [3H]testosterone and [14C]oestradiol or [3H]androstenedione and [14C]oestrone the dynamics of androgen and oestrogen metabolism and production in patients with hyperthyroidism were measured. The metabolic clearance rates of testosterone and oestradiol were decreased but those of androstenedione and oestrone were within the normal range. The conversion ratios of testosterone to androstenedione and of testosterone to dihydrotestosterone (DHT) were decreased whereas those of androstenedione to testosterone and androstenedione to DHT were increased. These changes could be explained by increased serum levels of sex hormone binding globulin which binds testosterone and DHT but not androstenedione. The fraction of androstenedione infused into and measured as oestrone in the blood was normal in seven out of nine subjects and the fraction of testosterone infused and measured as oestradiol was normal in all nine subjects. The production rates of testosterone and oestradiol were in the normal range but the production rates of androstenedione and oestrone were raised in half the subjects.

Physiological and many pathological changes in plasma sex-hormone-binding globulin (SHBG) levels have been attributed to the opposing effects of androgens which lower, and oestrogens which elevate, levels. We examined four clinical situations in which changes in SHBG levels may not be explained by sex steroid alterations. (1) Dexamethasone caused an increase in SHBG levels in hyperandrogenaemic hirsute women whether or not androgens were suppressed. (2) In male patients with untreated isolated gonadotrophin deficiency there was a highly significant correlation between SHBG levels and age, but there was no relationship between the levels of SHBG and those of plasma testosterone, androstenedione or DHEAS. (3) Two 46-XY siblings, phenotypic female subjects with complete androgen insensitivity, demonstrated a marked decline in SHBG levels between the ages of 9-13 and 12-16 years. (4) SHBG was suppressed in obese oligomenorrhoeic women while plasma concentrations of testosterone, androstenedione and oestradiol were normal and that of oestrone was elevated; however, the testosterone:SHBG ratio, an index of free testosterone, was elevated. These observations indicate that the decline in SHBG levels which normally occurs in men during the second decade of life is independent of androgen activity and is under the influence of as yet unidentified factors. Glucocorticoids in small doses under the influence of as yet unidentified factors. Glucocorticoids in small doses increase SHBG levels independently of sex steroid alterations while elevated free testosterone concentration may contribute to suppression of SHBG in obesity.

Two patients, aged 32 and 35 years, presented with gynaecomastia and a unilateral testicular tumour which proved to be a Leydig cell tumour. Pre-operative samples taken at 08.00 h on different days showed marked elevation of plasma oestradiol in the first patient, and very slight irregular oestradiol elevation in the second, plasma oestrone within the normal range in both patients, reduced plasma testosterone in the first patient and reduced or normal testosterone in the second, and low or low-normal serum LH and FSH in both patients. One of the patients received an oral dose of 100 mg of clomiphene citrate for 3 consecutive days which induced a rise in LH and FSH and a decrease in the 17-hydroxyprogesterone/androstenedione ratio. These data suggest the inhibiting effect of endogenous hyperoestrogenism on testicular steroidogenesis owing to both the reduction of gonadotropin secretion and a direct local negative effect on C 17,20-lyase. After human chorionic gonadotropin stimulation, oestradiol response was increased and abnormally prolonged, a finding which may be helpful when diagnosing a feminizing Leydig cell tumour; testosterone reached normal values. After removal of the tumoural testis, gynaecomastia regressed within a few days, gonadotropins increased, oestrogens dropped, testosterone and 5 alpha-dihydrotestosterone normalized in one patient but remained low in the other at day 30. The Leydig cells outside the tumour appeared morphologically normal, but the count gave evidence of juxtatumoural Leydig cell hyperplasia in areas where the tumour was well encapsulated while showing a significant reduction at a distance from the tumour and in the contralateral testis by comparison with control testes.(ABSTRACT TRUNCATED AT 250 WORDS)

Phenolic steroid sulphotransferase activity for both oestradiol and oestrone was identified in male rat liver cytosol in the 30 000-40 000 Mr fractions on gel filtration when activity was assayed at pH 5.5 (pH optimum 5.5-6.0). Activity for oestradiol but not oestrone was found in the 60 000-70 000-Mr range when assayed at pH 8.0 (pH optimum biphasic, 5.5-6.0 and 7.0-8.0). Km for oestradiol (1.3 microM) was lower than published values for hydroxysteroid sulphotransferases (15-35 microM) and previously reported oestradiol sulphotransferases (71-85 microM). At above 2 microM-oestradiol phenolic sulphotransferase activity exhibited substrate inhibition. The phenolic steroid sulphotransferase activity was found to be distinct in chromatofocusing from organic-anion-binding and bile acid-binding proteins previously identified in this Mr range. Further purification on hydroxyapatite yielded a 44-fold enriched fraction that contained two monomeric bands, Mr 32 500 and 29 500.

A double blind crossover study of transdermal oestradiol (50 micrograms/day) and ethinyl oestradiol (20 micrograms/day) was conducted with 25 postmenopausal women. Transdermal oestradiol increased circulating levels of oestradiol and oestrone. Both preparations favourably improved patients' symptoms and vaginal cytology, lowered gonadotrophin levels and urinary calcium loss and gave a satisfactory menstrual pattern. Transdermal oestradiol had no effect on measures of hepatic function whereas oral ethinyl oestradiol significantly altered levels of sex hormone binding globulin, plasma renin substrate and lipoproteins. Transdermal oestradiol has a comparable beneficial effect on postmenopausal symptoms to ethinyl oestradiol without the adverse effects on hepatic proteins.