SEX HORMONE BINDING GLOBULIN IN SALIVA

Measurement of salivary steroid hormone concentrations has frequently been advocated as a convenient alternative to plasma measurements. This is partly due to the belief that salivary steroid concentrations are a reliable reflection of the plasma free hormone level, a belief reinforced by earlier inability to demonstrate the presence of significant quantities of steroid binding proteins. Recent reports confirm that such quantities of these proteins are present in saliva and that they retain their steroid binding activity. We have measured sex hormone binding globulin (SHBG) and albumin in saliva from 14 men, 21 non-pregnant women and 36 pregnant women. No differences in the concentration of salivary albumin was evident in any of the groups studied whereas a significant difference in the concentration of SHBG was evident between men and non-pregnant women, and non-pregnant and pregnant individuals. Although much lower, salivary SHBG and albumin concentrations broadly reflect those found in plasma. Furthermore, a highly significant correlation existed between salivary SHBG and albumin concentrations in all groups studied. It now seems generally accepted that the albumin present in saliva arises from contamination by either traces of blood or gingival fluids. The close relationship between the concentrations of albumin and SHBG in saliva suggests that they both gain entry by a similar route. Furthermore, their presence may significantly influence the concentration of certain steroids in saliva, and this may explain the occasional failure of salivary steroid concentrations to accurately reflect the plasma free hormone levels.     

DEMONSTRATION OF SEX HORMONE BINDING GLOBULIN IN HUMAN CEREBROSPINAL FLUID

This study demonstrates the existence of sex hormone binding globulin (SHBG) in human cerebrospinal fluid (CSF) by means of a highly sensitive radioligand saturation assay that has been recently described by us for measurement of SHBG in human plasma. The molecular similarity of this 5 alpha-dihydrotestosterone binding protein with plasma-SHBG was substantiated by a number of experiments in which the CSF-protein displayed the same properties as plasma-SHBG with respect to thermolability, affinity, specificity and sedimentation rate. SHBG levels in the CSF of normal women were found to be 0.139 +/- 0.04 nmol/l (mean +/- standard deviation), and in normal men to be 0.083 +/- 0.03 nmol/l respectively. CSF-SHBG in patients with a variety of neurological diseases associated with different degrees of a blood-CSF barrier disturbance, showed a good correlation with commonly determined parameters such as CSF-albumin and CSF-IgG that are known to be of plasma origin. The concept of CSF-SHBG originating from plasma by restricted diffusion is strongly supported by the finding that the CSF/plasma ratio of SHBG is independent of the plasma-SHBG concentration in the entire physiological range. Possible diagnostic and pathophysiological implications of this so far undetected CSF-constituent are discussed with regard to neurological and endocrine abnormalities.     

SEX HORMONE BINDING GLOBULIN IN POSTMENOPAUSAL WOMEN: A PREDICTOR OF OSTEOPOROSIS SUPERIOR TO ENDOGENOUS OESTROGENS

To quantify the role of endogenous oestrogen activity in osteoporosis we measured relative metacarpal cortical area (RCA), body mass, serum oestrone, oestradiol, androstenedione, and sex hormone binding globulin (SHBG) in 746 postmenopausal women aged 53 to 76 years, sampled from the general population. The occurrence of fractures and the rate of loss of RCA (delta-RCA) were determined over the previous 9 years. Both RCA and delta-RCA were significantly related to body mass, serum oestrone, oestradiol, and SHBG. The influence of the first three variables appeared to be bone preserving, whereas the latter appeared to be bone wasting. Serum oestradiol, SHBG and body mass proved to have an independent relationship with RCA in multivariate regression analysis. The relationship to delta-RCA was statistically independent for serum SHBG only. Serum androstenedione was unrelated to either RCA or delta-RCA. In the total study population, body mass, serum oestrone, oestradiol and SHBG were not related to the occurrence of fractures over the previous 9 years. In the subgroup of 249 elderly women, aged 65-76 years, SHBG levels were significantly higher for women with type I osteoporotic fractures (vertebral and forearm fractures) as compared to controls. The results suggest a bone wasting influence of SHBG in postmenopausal women, possibly resulting in an increased risk of type I osteoporotic fractures in elderly women.     

DIET-INDUCED CHANGES IN SEX HORMONE BINDING GLOBULIN AND FREE TESTOSTERONE IN WOMEN WITH NORMAL OR POLYCYSTIC OVARIES: CORRELATION WITH SERUM INSULIN AND INSULIN-LIKE GROWTH FACTOR-I

The purpose of this study was to investigate the effect of calorie restriction on serum concentrations of sex hormone binding globulin (SHBG) in women with normal or polycystic ovaries (PCO) and to examine the possible role of insulin and insulin-like growth factor-I (IGF-I) in mediating changes in SHBG levels. Six normal subjects with mean (SD) body mass index (BMI) 25.5 (2.2) and five subjects with PCO (BMI 36.1 (3.7)) were studied before and after 2 or (PCO only) 4 weeks of a very low calorie diet (330 kcal/day; Cambridge Diet). In both normal women and patients with PCO there was a twofold increase in SHBG concentrations after 2 weeks and this was sustained in the PCO subjects for a further 2 weeks. The rise in SHBG was accompanied by a fall in free testosterone concentrations. There were parallel changes in serum insulin and IGF-I concentrations which decreased during the diet and there were significant negative correlations of SHBG with insulin in both normal subjects (r = -0.62) and women with PCO (r = -0.60). In addition, serum concentrations of an insulin-dependent small molecular weight (34 kDa) binding protein for IGF-I (IGF-BPI) increased significantly during dieting in both groups and were negatively correlated with serum insulin (controls, r = -0.56; PCO, r = -0.68) and positively correlated with serum SHBG levels (controls, r = 0.69; PCO, r = 0.63). In summary, these data indicate that in both normal subjects and those subjects with PCO, calorie restriction results in a highly significant increase in SHBG concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)     

OESTROGEN-RELATED CHANGES IN SEX HORMONE BINDING GLOBULIN LEVELS DURING NORMAL AND GONADOTROPHIN-STIMULATED MENSTRUAL CYCLES

Previous studies have identified no consistent change in sex hormone binding globulin (SHBG) levels during normal menstrual cycles. This is despite marked cyclical changes in plasma oestradiol concentration, and the observation that SHBG level increases in pregnancy, and after administration of exogenous gonadotrophin or synthetic oestrogens. The level of SHBG was measured in 19 normal females at 2 d intervals from day -8 to +10 where the preovulatory peak of oestradiol was designated as occurring on day 0. SHBG levels increased by a mean 15% +/- 4 (SEM) between the follicular and luteal phases (P less than 0.001) and this was due entirely to an increment between day 0 and +2. The change in SHBG levels was correlated with the change in oestradiol levels between days -8 and 0 (P less than 0.001). Fifty-six infertile patients were also studied. Twenty-seven received Pergonal alone whilst the other 29 received Pergonal after a preceding 5 d on Clomid. In both groups peak preovulatory oestradiol levels were greater than 3 times higher than in normal cycles. SHBG levels showed no change in the follicular phase but rose markedly during the luteal phase. These increases were significantly correlated with peak preovulatory oestradiol concentration but showed no relationship with mid-luteal progesterone concentration. We conclude that supranormal levels of oestradiol cause marked increases in SHBG binding capacity and increases in SHBG level of a lower order occur shortly after the preovulatory peak of oestradiol in the normal menstrual cycle.     

A COMPARISON OF THE EFFECTS OF DANAZOL AND GESTRINONE ON TESTOSTERONE BINDING TO SEX HORMONE BINDING GLOBULIN IN VITRO AND IN VIVO

Danazol and gestrinone are both effective agents in the treatment of endometriosis. Their mechanism of action is unknown but may be related to their androgenic activity, which is at least partly dependent on increases in the proportion of testosterone which circulates unbound to plasma protein. We have quantified these increases in patients on treatment, and by experimentation in vitro have demonstrated the relative importance of the reduction of sex hormone binding globulin (SHBG) binding capacity and competition with testosterone for SHBG binding sites by the drugs and some of their metabolites. The mean SHBG binding capacity in patients treated with danazol (400 mg/d, n = 7) and gestrinone (5 mg/week, n = 7) fell from 66.9 and 56.4 nmol/l to 36.1 and 28.1 nmol/l, after 1 week's treatment and to 11.1 and 7.1 nmol/l after 4 weeks respectively. Despite the similarity between the falls in SHBG binding capacity there was a significantly greater increase in % free testosterone in plasma samples from patients treated with danazol than in those from patients treated with gestrinone at 1 week. Experiments in vitro suggest that this was largely due to ethisterone (a major metabolite of danazol) competing with testosterone for SHBG binding sites. After 4 weeks on treatment there was a similar, near maximal reduction in SHBG binding of testosterone in both treatment groups. At the low levels of SHBG binding capacity reached by this time the extra effect of any competition for binding sites was much reduced.     

DECREASED SEX HORMONE BINDING GLOBULIN (SHBG) AND INSULIN-LIKE GROWTH FACTOR BINDING PROTEIN (IGFBP-1) IN EXTREME OBESITY

Obesity may be characterized by abnormal sex steroid secretion and reduced sex hormone binding globulin (SHBG) which in turn is related to fat distribution and insulin secretion. Recent in-vitro and in-vivo evidence suggests that insulin is the common mechanism regulating the secretion of SHBG and insulin-like growth factor small binding protein (IGFBP-1). IGFBP-1 appears not only to be a carrier for insulin growth factors (IGFs) but also to play an active role in growth processes, independent of growth hormone secretion. We have examined the possible relationship between fasting insulin, SHBG, testosterone, IGF-1, IGFBP-1 and fat distribution in 25 extremely obese, menstruating women (mean weight 107 +/- 3 kg) with normal glucose tolerance. Fat distribution was assessed from measurements of the waist to hip ratio (W/H). The obese women showed an elevated fasting insulin (mean +/- SEM; 21 +/- 2 mumol/l), a normal IGF-1, but reduced IGFBP-1 (14.6 +/- 2 micrograms/l); in 15 women IGFBP-1 levels were undetectable by the present assay. In addition, SHBG levels were reduced in the obese women (24 +/- 2 nmol/l) but total testosterone values (1.9 +/- 0.1 nmol/l) were normal. The elevated fasting insulin levels were positively correlated with increasing upper segment obesity as expressed by a rising W/H ratio (P less than 0.01, r2 = 0.306) and inversely correlated with SHBG (P less than 0.01, r2 = 0.483). Similarly, reduced SHBG values showed an inverse correlation with increasing W/H ratio (P less than 0.001, r2 = 0.383). No correlation was found between IGFBP-1 and W/H ratio but a strong positive correlation was seen between IGFBP-1 and SHBG (P less than 0.001, r2 = 0.466). Furthermore, an equally significant inverse correlation was found between IGFBP-1 and insulin levels (P less than 0.001, r2 = 0.474).(ABSTRACT TRUNCATED AT 250 WORDS)     

DOSAGE-RELATED EFFECTS OF DANAZOL ON SEX HORMONE BINDING GLOBULIN AND FREE AND TOTAL ANDROGEN LEVELS

Danazol is known to cause marked suppression of sex hormone binding globulin (SHBG) levels in plasma and to increase the proportion of plasma testosterone unbound to protein but the effect on the concentration of total and free testosterone is unclear. Twenty-five patients with endometriosis were treated daily for 6 months with doses of danazol ranging from 50 to 600 mg. The fall in SHBG and rise in percent free testosterone was dose-related during the early part of treatment. Suppression of total testosterone and 5 alpha-dihydrotestosterone levels occurred and was probably due to increases in metabolic clearance rates. The observed fall in androstenedione levels was related to the incidence of menstrual abnormality, suggesting that this might be due to reduced ovarian activity. The concentration of free testosterone increased by a factor of two in the first week but subsequently returned to levels of between 25 and 50% above pretreatment levels. This pattern of changes may be due to the rise in metabolic clearance rates being dependent on induction of enzymes of androgen metabolism.     

MEASUREMENT OF SEX HORMONE BINDING GLOBULIN IN HUMAN AMNIOTIC FLUID: ITS RELATIONSHIP TO PROTEIN AND TESTOSTERONE CONCENTRATIONS, AND FETAL SEX

Sex hormone binding globulin (SHBG) has been identified and quantified in human amniotic fluid. Identification was based on its electrophoretic mobility on polyacrylamide gels and its steroid binding characteristics, which were identical to those attributed to SHBG in pregnancy serum. Amniotic fluid SHBG binding capacity was measured by competitive saturation analysis using [³H]-5α-dihydrotestosterone as the labelled ligand, after removal of endogenous steroids with dextran-coated charcoal. Similar amniotic fluid SHBG binding capacities were found in samples taken during early (13–20 weeks, 8.5 ± 5.1 (SD) nmol/l, n= 10) and late (36–37 weeks, 8.7 ± 3.0 nmol/l, n= 28) pregnancy. In comparison with pregnancy serum SHBG levels (390 ± 140 nmol/l, n= 5), amniotic fluid SHBG was not enriched in relation to the relative concentrations of total proteins, albumin or transferrin. Amniotic fluid is therefore not a better source for the purification of SHBG than pregnancy serum. There were no differences in amniotic fluid SHBG levels with respect to fetal sex, but positive correlations were observed between SHBG binding capacities and testosterone concentrations in amniotic fluid from both male (r= 0.68, P < 0.001) and female (r= 0.53, P < 0.05) fetuses. It is suggested that SHBG may sequester free testosterone in amniotic fluid, and that measurements of SHBG in amniotic fluid may help to more accurately identify fetal sex in cases where borderline amniotic fluid testosterone concentrations are found.     

SERUM SEX HORMONE CONCENTRATIONS IN INSULIN DEPENDENT DIABETIC WOMEN WITH AND WITHOUT AMENORRHOEA

Abnormal steroid secretion may contribute to anovulation in insulin dependent diabetic patients with amenorrhoea. We have measured serum sex hormone-binding globulin (SHBG) and free and bound oestrogen and androgen levels in 17 such patients. As controls we included 17 patients with insulin dependent diabetes mellitus and normal menstrual cycles, 21 regularly menstruating normal women (both sampled during early follicular phase), and 23 non-diabetic patients with amenorrhoea. The diabetic patients with normal cycles had significantly higher serum concentrations of delta 4-androstenedione and testosterone than the normal women (P less than 0.01). The amenorrhoeic diabetics in contrast had significantly lower serum concentrations of SHBG, 5 alpha-dihydrotestosterone and free and total oestradiol-17 beta than either group of menstruating women (P less than 0.05), and significantly lower concentrations of delta 4-androstenedione (P less than 0.01), dehydroepiandrosterone sulphate (P less than 0.01), testosterone (P less than 0.01), and oestrone (P less than 0.05), than the cycling diabetics. The two amenorrhoeic groups had similar free and bound sex hormone concentrations except that delta 4-androstenedione levels were significantly lower in the diabetics (P less than 0.01). We conclude that the low sex hormone levels in diabetic women with amenorrhea may be due to suppression of the hypothalamic-pituitary axis in view of the impaired LH secretion found in these patients and that excess androgen secretion seems not to be of aetiological importance in amenorrhea related to diabetes mellitus. The decreased steroid levels in amenorrheic diabetics is due to their suppressed ovarian function while the increased androgen levels in diabetics with regular cycles are probably of ovarian origin.     

EFFECTS OF ETHINYLOESTRADIOL ON PLASMA LEVELS OF PITUITARY GONADOTROPHINS, TESTICULAR STERIODS AND SEX HORMONE BINDING GLOBULIN IN NORMAL MEN

Daily measurements of plasma FSH, LH, prolactin, testosterone, 17β-oestradiol and sex hormone binding globulin (SHBG) activity were made in eight healthy, normal men during treatment with oral ethinyloestradiol (EE₂) in a dose of 30 μg/day for 5 days following a 5-day control period. No significant changes in plasma levels of FSH and prolactin during oestrogen treatment occurred. In contrast, plasma concentrations of both LH and testosterone showed a biphasic pattern. Following an initial suppression during the first 3 days of oestrogen treatment both LH and testosterone increased again to baseline values despite continuation of oestrogen administration. The secondary rise of both hormones was associated with (and probably resulted from) a nearly 100% increase in the plasma concentration of SHBG binding activity, and hence reduction of free testosterone index (FTI). Unlike testosterone, plasma 17β-oestradiol during EE₂ administration did not show a biphasic pattern, but a progressive decline that was positively correlated with the fall in FTI. The rapidity of onset and magnitude of the observed rise in SHBG levels emphasizes the need for measurement of this binding protein (or the free testosterone fraction) in studies on feedback regulation of gonadotrophins employing exogenous EE₂ in human males. The observed increase of SHBG to supraphysiological values suggests that currently employed EE₂ doses in such studies may be less ‘physiologic’ than is often assumed.     

ABNORMAL SEX STEROID SECRETION AND BINDING IN MASSIVELY OBESE WOMEN

We have measured the plasma concentrations of sex steroids and sex hormone- binding globulin (SHBG) in twenty-three massively obese women and ten age-matched lean female volunteers. In the obese women increased plasma testosterone (obese 3·2 ± 0·5 nmol/1 controls 1·7 ± 0·5 nmol/1, P < 0·3) and androstenedione concentrations (obese 9·7 ± 1·2 nmol/1, controls 4·4 ± 0·6 nmol/1, P = < 0·01) an increased ratio of oestrone:oestradiol (obese 2·4 ± 0·4, controls 1·0 ± 0·1, P = < 0·1) and decreased SHBG levels (obese 30 ± 4 nmol/1, controls 60 + 8 nmol/1, P = <0·001) were found. Obesity differed from the polycystic ovary syndrome (in which a similar pattern of changes of sex steroid concentrations and binding are seen) in that it was associated with normal increases in serum luteinizing hormone (LH) follicle stimulating hormone (FSH) levels in response to the administration of LHRH. We conclude that the common occurrence of menstrual abnormalities in obesity results from abnormal secretion and binding of sex steroids. In addition, the unaltered secretion of LH and FSH in the presence of such changes is evidence for a disorder of hypothalamic function.     

GROWTH HORMONE AND PROLACTIN SECRETION AFTER GROWTH HORMONE-RELEASING HORMONE ADMINISTRATION, IN ANOREXIA NERVOSA PATIENTS, NORMAL CONTROLS AND TAMOXIFEN-PRETREATED VOLUNTEERS

Anorexia nervosa is associated with several abnormalities in GH secretion elicited by different stimuli. To investigate the precise mechanism of this alteration, GHRH was administered to 14 women: a group of eight anorexia nervosa patients in the acute phase of their illness and a control group of six age-matched volunteers. As patients with anorexia nervosa have chronic low oestrogen values, the volunteer women of the control group underwent a second GHRH test after pretreatment with the oestrogen receptor blocker tamoxifen. GHRH 1-29 (1 μ g/kg i.v.) induced a GH peak (mean±SEM) of 28.2 ±5.1 ng/ ml (GH ng/ml ± 2 = mU/l) at 30 min in the anorectic patients. This value was no different from the GHRH-stimulated GH peak in the control women (28.1 ± 100 ng/ml). Tamoxifen pretreated women had a GH peak after GHRH of 35.6 ± 9.7 ng/ml, not significant versus control test. Compared with the control group, oestrogen levels were significantly lower in anorectic patients and higher in tamoxifen-treated women. GHRH administration induced a small PRL peak at 15 min that was similar in the three groups tested. After this 15 min peak, PRL in both anorexic and tamoxifen-treated women returned toward basal values steadily. However, in untreated control women a second PRL peak was evident at 60 min. In conclusion, GHRH-induced GH secretion in anorexia nervosa patients was similar to that in control subjects and in controls under oestrogen receptor blockade.     

THYROXINE BINDING GLOBULIN DEFICIENCY IN A FAMILY WITH TYPE I HYPERLIPOPROTEINAEMIA

A familial type I hyperlipoproteinaemia is described in three members of a family of eleven; on the basis of LPL activity and HDL content of plasma three other members of the family have been diagnosed to be heterozygotes without other disturbances in their lipid spectrum. The distribution of this lipid disorder is in accordance with an autosomal recessive inheritance pattern. In this family a second hereditary condition, thyroxine binding globulin deficiency, was found in addition to the hyperlipoproteinaemia. The inheritance of this condition appears to be as an autosomal dominant. An interrelated inheritance pattern of both conditions could not be proved, but both traits may be located on the same chromosome at some distance from another to allow recombination.     

血浆性激素水平与隐睾症的关系

作者应用放射免疫法测定了25例双侧或单侧隐睾患儿及15例同龄正常儿童的血浆睾酮(T)、双氢睾酮(DHT)和雌二醇(E_2)水平,旨在探讨隐睾症的内分泌因素。结果显示双侧隐睾组平均DHT水平显著低于其他组,提示DHT是介导睾丸下降的活性雄激素;DHT产生过少是隐睾的内分泌因素之一。     

THE EFFECT OF WEIGHT LOSS ON SEX STEROID SECRETION AND BINDING IN MASSIVELY OBESE WOMEN

We have previously reported increased testosterone and androstenedione concentrations and decreased sex hormone binding globulin (SHBG) concentrations in the plasma of massively obese women. We now report that these plasma hormone concentrations return to normal in twelve of the same women after substantial weight reduction and these changes are associated with more normal menstrual cycles. We conclude that body weight and fat are important determinants of sex steroid secretion and binding and thus influence menstrual function.     

HUMAN CORTICOSTEROID BINDING GLOBULIN

The literature on corticosteroid binding globulin (transcortin) in the human is reviewed under the following headings: physicochemical properties, biosynthesis, measurement, and physiological, pharmacological and pathological variations with particular emphasis of the effects of pregnancy and oral contraceptives. Finally, the physiological implications of corticosteroid binding globulin are discussed.     

SERUM T3 AND T4 LEVELS IN PATIENTS WITH ANOREXIA NERVOSA SHOWING TRANSIENT HYPERTHYROIDISM DURING WEIGHT GAIN

Serum thyroxine (T4) and triiodothyronine (T3) levels were measured in a group of thirty-three patients with anorexia nervosa (AN) and compared with twenty-five control women presenting with hirsutism and twenty-one patients with primary myxoedema. T3 levels in the AN patients were significantly lower than in the control subjects and in the patients with myxoedema while T4 levels were significantly higher than in the patients with hypothyroidism but significantly lower than in the control group. Seventeen anorexia patients had further T3 and T4 levels measured following an arbitrary 25% weight gain and both levels had increased significantly. For individual patients, the absolute rise in T3 levels was significantly correlated with the rate of weight gain. Thirteen patients had serial T3 and T4 levels measured during their periods of weight gain. Eight of these subjects showed a gradual rise in T3 levels from subnormal or low normal levels to values in the upper normal range. Four subjects showed a distinct and self limiting overshoot of T3 levels and, associated with this, the patients had clinical features of mild hyperthyroidism.     

LUTEINIZING HORMONE RESPONSE TO DOMPERIDONE IN HYPERPROLACTINAEMIC WOMEN WITH PITUITARY MICROADENOMAS

Administration of a dopamine (DA) antagonist, domperidone, increased circulating levels of LH in hyperprolactinaemic-amenorrhoeic women with pituitary microadenomas but not in normal women in the early follicular phase of the menstrual cycle. This drug does not readily cross the blood-brain barrier and therefore the site of action of domperidone could be the pituitary gland or the median eminence. As the simultaneous administration of GnRH and domperidone did not increase the GnRH-induced LH release in hyperprolactinaemic women, the site of action of domperidone is likely to be the median eminence.     

WEIGHT GAIN AND REPRODUCTIVE FUNCTION: ULTRASONOGRAPHIC AND ENDOCRINE FEATURES IN ANOREXIA NERVOSA

Pelvic ultrasonographic measurements and reproductive hormone levels in 36 patients with anorexia nervosa were followed as they gained weight during inpatient treatment. In 24 patients who were severely malnourished (69% of premorbid weight) the ovaries were small and amorphous and the levels of LH, FSH and oestradiol were very low. Weight gain led to the appearance of multifollicular ovaries when levels of LH and oestradiol remained low but FSH levels had increased resulting in an LH:FSH ratio of less than 1. The emergence of a dominant follicle in 19 patients after weight gain (to 97% of premorbid weight) was accompanied by an increase in uterine area and associated with increased levels of LH and oestradiol and an LH:FSH ratio greater than 2. Among these patients with a dominant follicle at peak weight, 11 menstruated within a month of discharge. The weight at which normal ovarian morphology returned was related to premorbid weight (P less than 0.002) whereas body mass index (BMI) was poorly related. Our findings suggest that pelvic ultrasonography is probably the best indicator of the weight required for full endocrine recovery and offers advantages over sequential hormonal measurements, and is valuable in the management of patients with anorexia nervosa.