Sex hormone binding globulin: origin, function and clinical significance

Osteoporosis in men: a potential role for the sex hormone binding globulin

The exact mechanism of bone loss remains unknown in primary male osteoporosis. It has been suggested that estrogen and sex hormone binding globulin (SHBG) play a role in regulating bone turnover and bone mass in healthy men > 65 years of age. In the present study, 80 men (mean age 49.7 years) with bone mineral density >2.5 SD below the young adult value and 40 age-matched controls were recruited to evaluate the relationships between sex hormone levels, bone biochemical markers levels, and bone mineral density. Fasting serum samples were assayed for total and free testosterone total estradiol, and SHBG. The free androgen index, was calculated as: [total testosterone/SHBG * 100]. Bone remodeling was evaluated by measurement of urinary levels of the C-telopeptide of type I collagen (CTx) and free deoxypyridinoline (D-Pyr), serum osteocalcin, and bone-specific alkaline phosphatase (bSAP). There was no significant difference between controls and osteoporotic men according to age, body mass index (BMI), total testosterone, and estradiol. In contrast, serum SHBG level was significantly higher (+42.2%), whereas free androgen index was lower (-24.8%) in patients with primary or secondary osteoporosis. Testosterone and estradiol levels did not correlate with any bone resorption or bone formation markers. In contrast, stepwise linear regression analysis showed that SHBG was significantly correlated with D-Pyr (r = 0.45, p < 0.05) and CTx (r = 0.34, p < 0.05) in primary osteoporosis. In secondary osteoporosis, SHBG was correlated with D-Pyr (r = 0.48, p < 0.05) and bSAP (r = 0.55, p < 0.01). After adjustment for age and BMI, hip bone mineral density (BMD) was not associated with testosterone or estradiol but only with serum SHBG (r = -0.33, p < 0.01) in primary osteoporosis. The same relationship was observed in men with secondary osteoporosis (r = -0.34, p < 0.01). Among osteoporotic patients, spinal radiography showed at least one vertebral crush fracture in 36 men and none in 44. Serum SHBG concentration was significantly associated with the presence of vertebral fracture: the odds ratio was 2.0 (95% confidence interval [CI] 1.2-3.5) for an increase of one standard deviation of SHBG. In conclusion, the present study showed that serum SHBG concentration is increased in middle-aged men with primary or secondary osteoporosis and is correlated with bone remodeling markers, hip bone mineral density, and vertebral fracture risk.

Characterization of the oligosaccharides of plasma sex hormone binding globulin from noncirrhotic alcoholic patients

In previous reports we have demonstrated high plasma levels of sex hormone-binding globulin (SHBG) in asymptomatic alcoholic men. In the present work the physicochemical properties of SHBG from plasma of noncirrhotic alcoholic patients have been further compared with SHBG of control subjects. Steroid binding to SHBG was similar for the two groups: alcoholic men, K(d) of 0.62 +/- 0.07 nM and control individuals, K(d) of 0.70 +/- 0.10 nM. The structure of oligosaccharides attached to SHBG from controls and alcoholic men were determined by using serial chromatography. Our data indicated that 7% of SHBG of control individuals was not retarded by the Con-A column, whereas approximately 30% of SHBG of alcoholic men eluted in the void volume of Con A. Approximately 46% of SHBG of alcoholics applied to Con A, possessed biantennary complex oligosaccharides, as indicated by the fact that it could be eluted with methyl-alpha-D-glucopyranoside and by its retention on wheat germ agglutinin; in contrast, when SHBG from control men was analyzed, approximately 51% was eluted with methyl-alpha-D-glucopyranoside. Approximately 9% of the biantennary complex oligosaccharides on SHBG of control men and none of those on SHBG from alcoholic men were fucosylated on the chitobiose core, as determined by chromatography on Lenn culinaris lectin. Galactosylated oligosaccharides were also present on the SHBG fraction as indicated by its interaction with Ricinus communis-I. Approximately 24% of SHBG of alcoholic men and 39% of those on SHBG from control individuals applied to Con-A were retained and could be eluted with methyl-alpha-D-mannopyranoside. Evidence based on the binding on mannoside-eluted SHBG to Con-A, wheat germ agglutinin, and R. communis-I indicated that at least the SHBG in this fraction, from alcoholics or controls, contained two glycosylation sites and that the sites were differentially glycosylated.

Safety evaluation of phytosterol esters. Part 5. Faecal short-chain fatty acid and microflora content, faecal bacterial enzyme activity and serum female sex hormones in healthy normolipidaemic volunteers consuming a controlled diet either with or without a phytosterol ester-enriched margarine

A study was conducted in 12 healthy males and 12 healthy females (mean age 36 years, mean body mass index 24 kg/m2), to determine the effect of a margarine enriched with phytosterol esters on faecal short-chain fatty acids (SCFAs) and faecal bacterial enzyme activities, viable faecal microflora count, female sex hormones and serum cholesterol concentrations. The study design was a two-period, parallel dosing, randomized, placebo-controlled dietary study. Under controlled dietary conditions, participants consumed 40 g of the control margarine for 21 and 28 consecutive days for males and females, respectively. This was followed immediately by the second part of the study where subjects were equally and randomly allocated to consume daily 40 g of either the control or the test margarine, containing 8.6 g vegetable oil phytosterols (a mixture of beta-sitosterol, campesterol and stigmasterol), also for 21 or 28 days. All females were shown to have a regular menstrual cycle and were on an established method of contraception not involving oral contraceptives. When compared with the control group values, the test group showed a significant reduction in serum total and LDL cholesterol concentrations of 18 and 23% (P < 0.001; P < 0.001) respectively, in faecal lactic acid concentration (P = 0.039) and in serum progesterone levels (P = 0.021). There were no other significant treatment effects. Within each group a number of significant changes occurred compared to baseline. In the test group, faecal lactic acid concentration and the ratio of acetic acid:total SCFA; and the ratio of butyric acid:total SCFA, in the control group were both significantly reduced (P = 0.016). Compared to baseline, azo-reductase activity was significantly reduced in the control group (P = 0.047). Total faecal aerobes (P = 0.028), lactobacilli (P = 0.003) and staphylococci (P = 0.025) content was also significantly reduced in the control group, while in the test group only lactobacilli content was reduced (P = 0.019). Of the significant findings reported in this study, none was considered to be of biological importance except the beneficial reduction in serum total and LDL-cholesterol concentrations. The daily consumption of a margarine enriched with 8.6 g vegetable oil phytosterols did not affect the bacterial profile or the metabolic activities of the gut microflora, nor did it result in biologically relevant effects on serum female sex hormone levels. The margarine enriched with the vegetable oil phytosterols was well tolerated by both male and female volunteers.

Biphasic increase in serum inhibin B during puberty: a longitudinal study of healthy Finnish boys

We investigated the concentrations of serum inhibin B and the pro-alphaC-containing inhibins (pro-alphaC inhibin) and their relations to serum FSH levels in 38 healthy boys during their progression through puberty. Furthermore, we studied the effect of recombinant human FSH (rhFSH) on pro-alphaC inhibin production in three prepubertal gonadotropin-deficient boys. The serum inhibin B level increased between Tanner stages G1 and G2 (p < 0.02), simultaneously with the serum LH and testosterone concentrations. In advanced puberty, inhibin B changed less, and at stage G4, correlated negatively with serum FSH level (r = -0.57, p < 0.001, n = 37). The serum pro-alphaC inhibin level changed differently and increased also in advanced puberty. In prepubertal healthy subjects, the serum pro-alphaC inhibin and FSH levels correlated positively (r = 0.50, p = 0.051, n = 16), and during the rhFSH treatment of gonadotropin-deficient boys, serum pro-alphaC inhibin levels increased. These findings suggest that an increased production of inhibin B is an early event in puberty and that inhibin B can inhibit pituitary FSH secretion in the course of sexual maturation. Furthermore, they suggest that during puberty free inhibin (pro)-alpha-subunits, detected by the pro-alphaC inhibin assay, are present in large amounts and that FSH stimulates their production by prepubertal testes.

Sex steroids, bone turnover and bone mineral density in pre-, peri-, and postmenopausal women

To examine 1) the relationships between endogenous androgens and bone mineral density (BMD), 2) the relationships between sex-hormone binding globulin (SHBG) and BMD, and 3) the associations of endogenous androgens and SHBG with biochemical markers of bone turnover, a cross-sectional study was carried out in 88 healthy pre-, peri-, and postmenopausal women aged 35 to 74. Measurements of BMD(s) at the ultradistal radius and ulna, and the distal radius (using DEXA), estrogens, androgens, deoxypyridinoline (D-Pyr) and intact bone gla protein (I-BGP) were performed. In the multivariate regression models testosterone (T) was positively correlated with BMD at the ultradistal radius and ulna in perimenopausal women, and was positively correlated with BMD at the ultradistal radius and ulna, and the distal radius in postmenopausal women. T was positively associated with I-BGP in premenopausal women (r = 0.65, p < 0.01), and negatively associated with D-Pyr in pre- (r = -0.53, p < 0.05) and postmenopausal women (r = -0.49, p < 0.001). On the other hand, SHBG was negatively correlated with BMD at die ultradistal radius and ulna, and die distal radius in pre- and postmenopausal women in the models. SHBG was positively related to D-Pyr in pre(r = 0.57, p < 0.05) and postmenopausal women (r = 0.41, p < 0.01), and negatively related to I-BGP in postmenopausal women (r = -0.38, p < 0.01). These findings suggest that endogenous androgens may exert positive influences on BMD, and that SHBG may have negative effects on BMD.

Assessment of sex hormones and bone mineral density in relation to occurrence of fracture in men: a prospective population-based study

Patients with fragility fractures have low bone mineral density (BMD)--this statement is supported mainly by data on women. In this study, including only men, the objectives were to determine whether a decline in BMD alone or in combination with data on male sex hormones and skinfold thickness could be of value in predicting forthcoming fractures. We also wanted to find out whether high consumers of alcohol can be identified by measuring BMDs and male sex hormones. A prospective, population-based study was performed in the city of Malmö, Sweden. 242 men were randomly selected; all were of Scandinavian ethnic background, and were aged 50, 60, 70, and 80 years. Forearm BMD, testosterone, sex-hormone-binding globulin (SHBG), and skinfold thickness were analyzed. In addition, alcohol consumption and carbohydrate-deficient transferrin (CDT)--a marker of alcohol abuse--were analyzed. The study group was followed prospectively for 7 years and all fractures sustained were recorded. Prospectively, for a 1 SD decrease in forearm BMD, the Cox proportional hazard model gave a relative risk (RR) of 1.75 with a 95% confidence interval of 1.08-2.83 for a forthcoming fracture and 3.88 (1.30-11.57) for a hip fracture. For a 1 SD change in skinfold thickness, measured on the dorsum of the hand, a RR of 1.69 (0.99-2.87) for a forthcoming fracture was found and the corresponding value for hip fracture was 2.34 (1.10-5.00). Testosterone and SHBG did not enhance fracture prediction. Abusers of alcohol had, retrospectively, significantly more fractures. Individuals with alcohol consumption rates in the highest quartile had significantly higher CDT levels, but we were unable to identify high consumers of alcohol by analyzing BMD or sex hormones. In this study we found that forearm BMD and skinfold thickness could be used in predicting forthcoming fractures in men.

Age-related (type II) femoral neck osteoporosis in men: biochemical evidence for both hypovitaminosis D- and androgen deficiency-induced bone resorption

The problem of osteoporosis in men has recently been recognized as an important public health issue. To test the hypothesis that endocrine deficiency-mediated alterations in bone metabolism might contribute to osteoporotic fracture risk in elderly men, serum levels of 25-hydroxycholecalciferol (25(OH)D), 1,25-dihydroxycholecalciferol (1,25(OH)2D), intact parathyroid hormone (PTH), testosterone, and estradiol were measured in 40 males (mean age 73 years) who were consecutively recruited within 18 h following a fracture of the proximal femur, and in an equal number of community-living older men (mean age 72 years) who served as controls. In addition, circulating osteocalcin and urinary excretion of (deoxy)pyridinoline were determined as markers of bone formation and resorption, respectively. No differences were observed between the mean serum concentrations of osteocalcin and estradiol. Serum levels of 25(OH)D, 1,25(OH)2D, and testosterone, however, were decreased in hip fracture patients. When correcting for differences in vitamin D binding protein, differences in 1,25(OH)2D did not persist, whereas serum 25(OH)D was still significantly lower in patients than in controls (6.1 +/- 4.3 vs. 7.6 +/- 2.8, p = 0.01). Similarly, a highly significant deficit was observed in the free testosterone index, calculated from total testosterone and the level of sex hormone binding globulin (2.6 +/- 1.3 vs. 8.2 +/- 2.9, p < 0.001). Serum PTH and urinary pyridinium cross-links, however, were markedly increased in the fracture group. Moreover, in fracture patients, free 25(OH)D and free testosterone were both significant and mutually independent negative predictors of (deoxy)pyridinoline excretion. Although limited by its cross-sectional design, the present study suggests that both hypovitaminosis D and androgen deficiency may predispose to bone resorption in elderly men and in turn to remodeling imbalance and fracture risk.

Effects of experimentally induced mild hyperthyroidism on growth hormone and insulin secretion and sex steroid levels in healthy young men

Although triiodothyronine (T3) exerts major regulatory actions in both animals and humans, most clinical studies of T3 administration have been relatively short-term. The present study examined the effects of more than 2 months (63 days) of low-dose T3 treatment on overnight pulsatile growth hormone (GH) secretion, short-term insulin secretion, and of sex steroid levels in seven healthy, lean men studied at an inpatient metabolic unit. At baseline, there were strong correlations between sex hormone-binding globulin (SHBG) and several measures of GH production, including total GH production (r = .99), GH interburst interval (r = -.75), and GH mass (r = .82). SHBG was also inversely correlated with basal insulin secretion (r = -.74). There was a 42% increase in serum levels of total testosterone (18.5 +/- 1.3 to 26.3 +/- 1.8 nmol/L, P = .005) and a 150% increase in SHBG (18.0 +/- 2.2 to 44.9 +/- 7.0 nmol/L, P = .008) following T3 treatment. Estradiol and free testosterone levels were unchanged by treatment, although free testosterone decreased from 142.8 +/- 18.4 to 137.3 +/- 19.5 pmol/L. T3 treatment significantly reduced the GH interburst interval (P < .05) and produced slight increases in the measures of GH secretion. There were no statistically significant effects of T3 treatment on insulin secretion, although insulin peak amplitude, mass secreted per burst, and total production all decreased. We conclude that experimentally induced T3 excess in healthy men produces significant and sustained changes in sex hormone levels and GH secretion. Furthermore, there are strong associations between SHBG and both GH and insulin secretion independent of thyroid hormone excess that require additional study.

Sexual function in women with epilepsy

PURPOSE

To examine certain aspects of sexual behaviour and attitudes in a group of women with epilepsy using a validated questionnaire (Sexuality Experience Scales), and effects of antiepileptic drugs (AEDs) on sex hormone binding globulin (SHBG), total testosterone (TT), and free testosterone (FT).

METHODS

One hundred ninety-five women all attending a hospital-based epilepsy clinic were recruited. One hundred fifty-nine received AED therapy and 36 women did not. A control group of 48 women was also recruited. All women completed the first two Sexuality Experience Scales (SES 1 and SES 2), and those women in stable heterosexual relationships completed SES 3 and SES 4. At the same time blood was taken for TT and SHBG levels. FT was calculated using the method of Nanjee and Wheeler (22).

RESULTS

Women receiving AED therapy achieved significantly higher SES 1 and SES 2 scores than the rest of the women, suggesting that they adhered to a stricter sexual morality and were less open to psychosexual stimulation than the rest of the women treated. Women in the treated group were less likely to have received further education than the controls, a factor that influences SES 1 and SES 2 scores. There were no significant differences between the three groups on SES 3 or SES 4, with the exception of the orgasmic adequacy (OE) scale of SES 3 where those women in the treated group attained a higher mean score than the controls, suggesting that they found orgasm less satisfying. Women receiving AEDs had significantly higher SHBG and TT than controls and untreated patients. There were no differences in FT between the groups. Those women receiving AEDs also exhibited the expected midcycle rise in FT. There was no significant correlation between FT and the desired frequency of intercourse or enjoyment of it for the three groups.

CONCLUSIONS

Women in the treated group appeared to be more "moral" and less open to sexual approach, but those who had regular partners appeared to desire and enjoy intercourse as much as the control and untreated groups. This could be explained by differences in demographic characteristics of the study groups or be indicative of a bimodal distribution of sexual interest in these women. As FT was within physiological norms for each study group this cannot be cited as a cause for hyposexuality.

BONE MINERAL DENSITY, SEX HORMONES, AND LONG-TERM USE OF NEUROLEPTIC AGENTS IN MEN

OBJECTIVE

To study the prevalence and severity of bone mineral loss and its relationship to sex hormone levels in men on long-term neuroleptic therapy.

METHODS

Sixteen men with schizophrenia who were from 19 to 62 years old and had taken neuroleptic medication for 1 to 30 years had bone mineral density (BMD) of the lumbar spine and proximal femur measured by dual-energy x-ray absorptiometry. Results were compared with those from 16 age-matched control subjects. Serum testosterone, sex hormone-binding globulin, free testosterone index (FTI), prolactin, and pituitary gonadotropins were assayed and compared with age-matched Red Cross blood donor controls (N = 23 to 90 for the various assays).

RESULTS

At the lumbar spine and at two of the three sites in the proximal femur (trochanter and Ward's triangle but not femoral neck), the BMD was lower in patients than in controls. A statistically significant increase in prolactin and sex hormone-binding globulin and a significantly decreased luteinizing hormone and FTI were found in the treated versus the control group. In the patient group, a significant inverse relationship existed between age and BMD at all sites. Lumbar spine density was related directly to FTI (r = 0.607; P=0.05) and inversely to duration of treatment (r = -0.767; P<0.001), although both correlations were accounted for mainly by age associations in multiple stepwise linear regression. Prolactin values did not correlate with either BMD or FTI.

CONCLUSION

BMD was significantly lower with long-term neuroleptic use. In the lumbar spine, these changes may be related to the associated findings of decreased free testosterone and hyperprolactinemia, although the significance of other factors such as an independent drug effect, the psychiatric disease itself, and lifestyle cannot be excluded.

A twin study of polycystic ovary syndrome and lipids

Our objective was to assess the relative contribution of genetic and environmental factors (particularly androgens) on circulating levels of lipid fractions and to determine the effect, if any, of polycystic ovary syndrome (PCOS) on lipid fractions. The study was carried out in the outpatient clinic of the Royal Hospital for Women, Paddington, Sydney, Australia. A group of 19 monozygotic (MZ) and 15 dizygotic (DZ) twin pairs was identified from the National Twin Register. Ultrasound clinical and biochemical parameters were used to define polycystic ovaries. Serum androgen and lipid fractions were also measured. Eleven pairs of twins (five MZ, six DZ) were scan discordant (i.e. one twin had polycystic ovaries and the co-twin did not). Serum levels of the lipoprotein fractions in twins with polycystic ovaries were not significantly different from the levels found for their co-twins with normal ovaries. There were no significant correlations between androgen-related hormones and any of the lipid measurements. Body mass index (BMI) was positively correlated with triglycerides and lipoprotein (a), and negatively correlated with high-density lipoprotein cholesterol (HDL-C). Sex hormone-binding globulin (SHBG) levels were negatively correlated with triglycerides and lipoprotein (a) and positively associated with HDL-C. Fasting insulin levels were significantly correlated with triglycerides and negatively with HDL-C. The MZ intraclass correlation exceeded that of the DZ twin pairs for all the lipid variables measured. The heritability estimates for lipoprotein (a), apolipoprotein B, total cholesterol and HDL-C were 0.95, 0.56, 0.48 and 0.54, respectively. However, the intraclass correlation coefficient for triglycerides was not significantly different between MZ and DZ twins, but maximum likelihood analysis indicated that at least 10% of the variance of the circulating triglyceride concentration is determined by genetic factors. We conclude that twins discordant for the PCOS do not have significantly different lipid fractions.

Body iron stores decrease in boys during pubertal development: the transferrin receptor-ferritin ratio as an indicator of iron status

The transferrin receptor in serum provides a useful measure of tissue iron deficiency and the rate of erythropoiesis, whereas serum ferritin reflects the amount of storage iron in normal subjects. We studied the serum transferrin receptor and the transferrin receptor-ferritin ratio in 57 healthy prepubertal or early pubertal boys and followed them at 3-mo intervals for 24 mo to evaluate their iron status during puberty. The mean laboratory parameters changed as follows: Hb from 13.0 to 13.3 g/dL (p = 0.01), mean corpuscular volume from 85 to 84 fL (p = 0.0001), transferrin receptor from 6900 to 7200 micrograms/L (p = 0.03) ferritin from 36 to 23 micrograms/L (p = 0.0001), and transferrin receptor-ferritin ratio from 230 to 400 (p = 0.0001). At the start of the investigation, the serum transferrin receptor was elevated (> 9000 micrograms/l) or ferritin low (< = or 12 micrograms/L) in fewer than 2% of the boys. During the subsequent 2 y the proportion of boys with an elevated transferrin receptor or low ferritin value increased. The two parameters were simultaneously abnormal in none of the boys initially, but in about 3% of the boys 2 y later. The change in transferrin receptor-ferritin ratio was closely correlated with genital development. The proportion of elevated transferrin receptor-ferritin ratios increased 4.5-fold during the 2 y, indicating the high responsiveness of the ratio. At the end of the study, iron therapy was started to eliminate any iron deficiency. In response to the therapy, the mean transferrin receptor-ferritin ratio fell to 210 +/- 19, i.e. close to the level at the beginning of the study. The marked responses of the transferrin receptor and the receptor-ferritin ratio to iron therapy reflect the dependence of these parameters on iron status rather than on physiologic differences in the rate of erythropoiesis.

Value of buserelin testing in the evaluation of hirsute women

It has been recently reported that many hirsute women are affected with functional ovarian hyperandrogenism (FOH)-a term that encompasses the heterogeneous polycystic ovary syndrome- and show an abnormal ovarian steroidogenic response to gonadotropin-releasing hormone (Gn-RH) agonists. The aims of the present study were to determine the prevalence of FOH by the assessment of 17-hydroxyprogesterone (17-OHP) response to the Gn-RH agonist buserelin, to correlate these abnormal responses to other parameters suggestive of PCOS, and to assess the possible adrenal origin of hyperandrogenism. Therefore, in 33 consecutive women with hirsutism serum LH, FSH, 17-OHP, dehydroepiandrosterone sulfate (DHEA-S), androstenedione (A), cortisol levels were evaluated in basal conditions and after the administration of buserelin (0.5 mg sc) and ACTH (tetracosactide 0.25 mg iv). Two patients were affected with a non classic congenital adrenal hyperplasia (CAH)-21OH deficiency. In 5 other women ACTH test caused a rate increase 17-OHP (30-0)/30 min > 19 nmol/L/min (0.25 +/- 0.03; mean +/- SE), suggesting the possible existence of heterozygote non classic CAH-21OH. One patient showed a DHEA-S response to ACTH (from 10.3 to 17.2 mumol/L), which was compatible with late-onset 3 beta-Hydroxy-delta 5 steroid dehydrogenase deficiency. Out of the 25 patients with normal responsiveness to ACTH, 11 women (group A) showed higher 17-OHP and A levels, in comparison to normal women, both in basal conditions (17-OHP = 4.18 +/- 0.72 vs 1.74 +/- 0.34 nmol/L, p < 0.005; A = 11.8 +/- 1.2 vs 6.0 +/- 0.7 nmol/L, p < 0.05) and after buserelin (17-OHP = 15.61 +/- 1.31 vs 6.96 +/- 0.9 nmol/L; A = 19.0 +/- 1.9 vs 7.5 +/- 0.8 nmol/L; p < 0.001). In 6 of these 11 patients basal and buserelin-stimulated LH levels were higher than in normals. The remaining 14 patients (group B) showed normal baseline and buserelin-stimulated 17-OHP and A concentrations. In this group only 2 patients had high basal and stimulated LH levels. An augmented LH/FSH ratio was present in 5 and 1 cases of groups A and B, and polycystic ovaries at ultrasonography were observed in 7 and 8 cases of groups A and B, respectively. It is to note that an abnormal 17-OHP response to buserelin was present also in 3 of the 5 patients with abnormal 17-OHP rise after ACTH test, suggesting an adrenal and ovarian cause of hyperandrogenism. In conclusion, an abnormal response to one or both stimulation test was present in 57% of cases: an adrenal origin of hirsutism was detected in 15%, a combined adrenal and ovarian origin was found in 9% and an ovarian cause was present in 33%. Buserelin testing is an useful means to reveal the presence of FOH.

Hypogonadism in Rhodesian sleeping sickness: evidence for acute and chronic dysfunction of the hypothalamic-pituitary-gonadal axis

OBJECTIVE

To investigate acute and long-term effects of Rhodesian sleeping sickness on the function of the hypothalamic-pituitary-gonadal (HPG) axis in men.

DESIGN

An observational, cross-sectional study.

SETTING

Primary health care centers under care of the National Sleeping Sickness Control Program in southeast Uganda.

PARTICIPANTS

Fifty-two male patients with sleeping sickness at different stages of treatment and 11 clinically healthy male volunteers recruited from health care personnel.

INTERVENTIONS

Patients and controls were questioned about loss of libido and impotence. All received 100 micrograms GnRH i.v. Blood was drawn before and 30 minutes after GnRH administration.

MAIN OUTCOME MEASURES

Frequency of loss of libido and impotence. Baseline T and sex hormone-binding globulin baseline and GnRH- stimulated serum LH and FSH concentrations.

RESULTS

Loss of libido and/or impotence were present in 39% of men with active disease before therapy, whereas 84% were biochemically hypogonadal. After cure, 45% of men still were symptomatic and 45% were biochemically hypogonadal. Compared with controls (806 +/- 59 pg/mL [conversion factor to SI unit, 0.03467]; mean +/- SEM), T concentrations were decreased substantially in patients before (249 +/- 48 ng/dL), during treatment (429 +/- 56 ng/dL), and after cure (431 +/- 58 ng/dL). Corresponding baseline LH concentrations were inappropriately low and the relative LH response to GnRH was reduced both before and during treatment (794% +/- 131% versus 322% +/- 68%). Follicle-stimulating hormone concentrations increased gradually up to 8.0 +/- 1.3 mIU/mL (conversion factor to SI unit, 1.00) at the end of treatment, returning to 4.2 +/- 0.6 mIU/mL after cure.

CONCLUSIONS

Rhodesian sleeping sickness causes acute and chronic HPG axis dysfunction. The clinical and biochemical picture suggest a combined central and peripheral hypogonadism. This is only in part reversible after cure and most likely due to direct parasitic infiltration and/or secondary inflammation causing necrosis and/or fibrosis at the pituitary and gonadal levels.

Expression of sex hormone-binding globulin mRNA in uterine leiomyoma, myometrium and endometrium of human subjects

This study was designed to evaluate the effect of sex hormone-binding globulin (SHBG) on the estrogen-dependent growth of human uterine leiomyoma. Levels of SHBG mRNA were analyzed using competitive reverse transcription-polymerase chain reaction-Southern blot analysis (RT-PCR-SBA). In normal uterine endometria, the levels of SHBG mRNA in the early/mid and late proliferative phases of the menstrual cycle were significantly lower than in the secretory phase (p < 0.01). In uterine myometria and leiomyomas, SHBG mRNA level showed no significant differences during the menstrual cycle, while the ratio of leiomyoma SHBG level to the corresponding myometrium SHBG level was >1 in 21 out of 23 cases (91%). Our results suggest that steroidal regulation of intracellular SHBG synthesis in the myometrium and the leiomyoma might differ from that in the endometrium, and that the mechanism of SHBG expression in leiomyoma might, in the process of tumorigenesis, be altered from that of corresponding normal myometrium, contributing to SHBG overexpression and the abundant estrogen supply.

Androgens and insulin resistance in type 1 diabetic men

OBJECTIVE

In healthy men, both high and low serum testosterone concentrations are associated with insulin resistance, whereas low concentration of sex hormone binding globulin (SHBG) is related to reduced insulin sensitivity. The aim of our study was to examine the association of sex hormones, SHBG, dehydroepiandrosterone (DHEAS) and insulin-like growth factor binding protein-1 (IGFBP-1) on insulin sensitivity in type 1 diabetic patients.

PATIENTS

We examined 23 male patients with the mean age of 29 +/- 1 years, body mass index 22.9 +/- 0.4 kg/m2, insulin dose 47 +/- 3 units/day, glycosylated haemoglobin (HbA1c) 7.8 +/- 0.3% and duration of diabetes 13 +/- 1 years.

DESIGN

Each patient was studied with a 4-hour euglycaemic (5.5 +/- 0.1 mmol/l), hyperinsulinaemic (612 +/- 26 pmol/l) clamp with indirect calorimetry. Muscle biopsies (quadriceps femoris) for the determination of glycogen synthase were performed in 15 patients before and at the end of the clamp.

RESULTS

Insulin infusion reduced the concentrations of IGFBP-1 by 90% (P < 0.001), DHEAS by 11% (P < 0.001), and SHBG by 4% (P < 0.01), whereas free or bound testosterone levels remained unchanged. The fall in IGFBP-1 level was closely related to the basal concentration (r = 0.99, P < 0.001). Basal SHBG concentration correlated directly with total (r = 0.51, P < 0.05) and non-oxidative glucose disposal (r = 0.41, P < 0.05), and with the decrease in lipid oxidation (r = 0.47, P < 0.05) during insulin infusion. The fall in SHBG was inversely related to the mean (30-240 min) FFA concentration during hyperinsulinaemia (r = -0.64, P < 0.001). The fractional activity of glycogen synthase at the end of insulin infusion correlated directly with fasting SHBG (r = 0.71, P < 0.01) and DHEAS concentrations (r = 0.67, P < 0.01).

CONCLUSIONS

In male type 1 diabetic patients: (1) acute hyperinsulinaemia decreases IGFBP-1, DHEAS and SHBG concentrations with the greatest decline in IGFBP-1, (2) SHBG concentration is positively associated with factors indicating good insulin sensitivity, (3) association between fuel homeostasis and SHBG, DHEAS and insulin antagonists suggests a network of these factors in the regulation of insulin action in type 1 diabetic patients.

Alcoholic hypogonadism: hormonal response to clomiphene

To investigate the androgen, weak androgen, estrogen, and gonadotrophin response to clomiphene in alcoholics, we determined in 63 male patients (25 with and 38 without liver cirrhosis) serum testosterone, sexual hormone binding protein (SHBG), dehidroepiandrosterone, androstenedione, LH, FSH, prolactin, and estradiol levels, on the first and the sixth day after admission, and after a course of 8 days of clomiphene 200 mg/day. The same test was performed on 15 healthy volunteers. Cirrhotic patients showed decreased basal testosterone levels and a loss of the circadian rhythm with recovery after clomiphene. Although basal testosterone levels in noncirrhotic alcoholics did not differ from those of the controls, there was a significant improvement after withdrawal. SHBG levels were higher in both groups of alcoholics than in controls, pointing to a worse degree of hypogonadism, because only the free hormone is active. Before the clomiphene test, serum LH and FSH levels were nonsignificantly higher in both groups of alcoholics than in the control group. After clomiphene both LH and FSH increased. Androstenedione and estradiol showed a (parallelism) similar behavior in alcoholic and in cirrhotic groups, showing in both cases higher levels than in the control group, and an increase after clomiphene, perhaps reflecting peripheral conversion of androgens to estrogens. Because clomiphene has no effect on the adrenal cortex, the increase of androstenedione after clomiphene points to its testicular origin (directly or after testosterone conversion) and not to an adrenal one. The highest serum estradiol levels were observed in cirrhotics with ascites or gynecomastia. We have not found any relation between serum hormone levels and alcohol intake nor with nutritional status.

Effects of abstinence on sex hormone profile in alcoholic patients without liver failure

Excessive ethanol ingestion induces hypoandrogenism in male subjects. To confirm its presence and to study its relationship with the degree of liver damage and alcohol abstinence, plasma sex hormones were measured in alcoholic patients without liver failure, after two different abstinence periods. Patients were 30 male chronic alcoholics admitted to the Alcoholism Ward for treatment of their addiction. On admission, we measured: testosterone (T), estradiol (E), follicle stimulating hormone (FSH), luteinizing hormone (LH) and sex-hormone binding globulin (SHBG). A liver biopsy was also performed. These measurements were repeated at discharge and were also done in 15 normal volunteers. On admission (mean abstinence 1.9 +/- 1.7 days) total T was similar to controls, FSH was lower (p < 0.02) and high levels of SHBG were found (3.5 fold increase, as compared to controls). Histologically, 9 patients had normal liver; 14 had moderate alterations and 7 showed marked alterations. Hormonal values were not different in these 3 groups. At discharge, 11.1 +/- 4.7 days after admission, T, E and FSH did not show significant changes but LH decreased (8.2 +/- 5.2 mIU/ml vs 12.9 +/- 4.1, p < 0.001); SHBG also decreased (65.4 +/- 21.6 nmol/l vs 117.2 +/- 33.3, p < 0.001) to values that still were twice those of controls. It is concluded that alcoholic patients without clinical signs of liver failure have normal plasma testosterone levels, irrespective of their histologic liver alterations and high plasma SHBG levels that decreased significantly after a short abstinence. The concomitant LH decrease suggests that hypoandrogenism is likely in these patients. Fast changes in SHBG levels rise the possibility that this protein is candidate marker of alcoholism.

Vitamin D status and sex hormone binding globulin: determinants of bone turnover and bone mineral density in elderly women

To examine the relation of the vitamin D status and the remaining estrogen activity with bone turnover and bone mineral density (BMD) in elderly women, BMD was measured at both hips using dual-energy X-ray absorptiometry and at the distal radius using single photon absorptiometry, in 330 healthy women aged 70 and over. Vitamin D metabolites, sex hormone binding globulin (SHBG), PTH(1-84), osteocalcin, alkaline phosphatase, and hydroxyproline and calcium excretion in 2 h fasting urine were measured. Multiple linear regression was used to adjust for potential confounders. In 65% of the women, serum 25(OH)D was below 30 nmol/l. Only values below a threshold for 25(OH)D were negatively related to serum PTH(1-84) (p = 0.02, threshold at 25 nmol/l) and to osteocalcin levels (p = 0.04, threshold at 30 nmol/l). BMD of the femoral neck and trochanter was positively related to serum 25(OH)D (left neck p = 0.001) with thresholds at 30 nmol/l whereas the distal radius was not (p = 0.32). Serum PTH was negatively related to BMD at all measurement sites (all p < 0.001). Serum SHBG, an inverse measure of estrogen activity, was positively related to osteocalcin levels (p = 0.004) and the urinary hydroxyproline/creatinine ratio (p = 0.002) and negatively related to the BMD of the trochanter (left trochanter p = 0.02) and the distal radius (p = 0.001). We conclude that in elderly women, serum 25(OH)D levels below 30 nmol/l are associated with secondary hyperparathyroidism and increased bone turnover. SHBG is positively related to bone turnover.(ABSTRACT TRUNCATED AT 250 WORDS)

Antioxidants and hormone-mediated health benefits of whole grains

Lignans and phytoestrogens have been associated with protective effect against hormone-related diseases, for example, cancer of the breast and prostate, and potential mechanisms for this effect have been reported. Antioxidants also appear to have some protective effect against diseases associated with reactive free radicals such as coronary heart disease and cancer. Whole grains contain some of these substances particularly the mammalian lignan precursors, vitamin E, other phenolic compounds, Se, and phytic acid. These substances may in part be responsible for the reduced risk of cancer and coronary heart disease associated with intake of high-fiber diets containing whole grains. Because they are more associated with the fiber in the outer layers of the grain, the intake of whole vs. refined grain is emphasized for optimum health benefits.

Effect of liver transplantation on sex-hormone disorders in male patients with alcohol-induced or post-viral hepatitis advanced liver disease

The effects of liver transplantation on the pituitary-gonadal axis and sex-hormone metabolism were evaluated by studying hormonal status (androgens, oestrogens, and gonadotropins) and sex-hormone-binding globulin levels in men with advanced liver disease of both alcoholic and viral origins. Comparison of the results prior to and 6 months after liver transplantation showed that successful liver transplantation in men induced significant differences in sex-hormone levels and in pituitary-gonadal function in both alcoholic and post-hepatitis patients. Plasma testosterone and dihydrotestosterone levels increased, oestrogen (oestrone and oestradiol) and androstenedione levels fell while gonadotropin (FSH and LH) levels increased. There was also a fall in plasma prolactin levels. Sex-hormone binding globulin plasma levels were elevated prior to transplantation and decreased thereafter. These data show that male patients with advanced liver disease have biological hypogonadism and feminization, irrespective of the aetiology, and that these abnormalities rapidly improve after successful liver transplantation. Therefore in men with advanced liver disease the biochemical signs of sex hormone disturbance are reversible and may be largely related to the liver disease.

Structure, function, and regulation of androgen-binding protein/sex hormone-binding globulin

Despite over 20 years of research, the functions of ABP and SHBG remain elusive. The major reason for this lack of knowledge has been the unavailability of natural mutants with clinical defects for study. There is strong evidence that these binding proteins do act to modulate the gene regulatory actions of nuclear sex steroid receptors by controlling the availability of androgens and estrogens. In plasma, SHBG controls the metabolic clearance rate of sex steroids. In addition there is strong evidence that they have a much broader function. The identification of plasma membrane receptors in target tissues and the finding of homologous domains in several developmental proteins support other functions. Moreover, other experiments suggest the proteins may actually be hormones or growth factors. These findings are not compatible with a model that has the proteins only regulating free steroid hormone levels. Obviously, much more experimentation will be necessary to reveal the functions of ABP and SHBG. The recent discoveries have offered several clues to their functions and open new routes for study. These experiments, coupled with newly developed techniques, such as gene knockout by homologous recombination, make one optimistic that the functions of these unique proteins will be deciphered in the near future.

Clinical implications of hyperinsulinaemia in women

In the polycystic ovary syndrome, hyperinsulinaemia is commonly found in women with hirsutism, oligomenorrhoea and acanthosis nigricans and this subset of patients possess adverse risk factors for coronary artery disease, particularly reduced HDL2 concentrations. Conversely, raised serum insulin concentrations are not common in women with PCOS in whom raised serum LH concentrations or regular menstrual cycles are present. We postulate that both direct ovarian and indirect actions of insulin (through changes in IGFI-I, IGFBP-I and SHBG concentrations) play important roles in determining androgen concentrations in women. Many intriguing questions follow from this link between the control of nutrition and reproduction and many old observations required re-examination in this new light. Vital to our understanding in this field will be the cause of moderate hyperinsulinaemia, the action of insulin on the normal ovary, and the importance of adverse surrogate risk factors for heart disease in hyperinsulinaemic women.

Androgen biology as a basis for the diagnosis and treatment of androgenic disorders in women. II

In the May 1993 issue of the Journal we reviewed the basic science of androgen biology in women. We now discuss the evaluation of suspected hyperandrogenism and the therapeutic modalities available.

Sex hormones and sex hormone-binding globulin in males with chronic viral hepatitis during recombinant interferon-alpha 2b therapy

The effect of long-term treatment with recombinant interferon-alpha 2b (IFN-alpha 2b) on luteinizing hormone (LH), testosterone, free testosterone, and sex hormone-binding globulin (SHBG) was evaluated in 7 male patients suffering from chronic viral hepatitis. The drug was given three times a week for 6 months in a single standard dose of 3 x 10(6) units. Hormone evaluations were performed in basal conditions and every 2 months for 12 months. Serum testosterone values decreased after IFN treatment, reaching the lowest levels at the 6th month. However, testosterone values did not fall below the normal range. Serum SHBG concentrations, which were above the normal range in basal conditions, also decreased after IFN. Serum-free testosterone and LH concentrations did not change during IFN therapy. IFN-alpha 2b at the dose and schedule employed was not responsible for any measurable imbalance in male sex hormones.

Androgen biology as a basis for the diagnosis and treatment of androgenic disorders in women. I

Disorders of androgen excess in women are common in the practice of dermatology. The literature regarding the evaluation and treatment of women with cutaneous hyperandrogenism (acne, hirsutism, and alopecia) is vast and is contained in numerous subspecialty journals. At first glance, the basic science knowledge required to understand androgen biology appears exceedingly complex. However, an understanding of androgen physiology and a familiarity with the relevant literature are the basis of appropriate evaluations and treatment recommendations. In the first of this two-part series, we review the basic science of androgen biology and pathophysiology in women. The second part of this series will cover the evaluation of suspected hyperandrogenic women and the therapeutic modalities that are available.

A clinical evaluation of a direct radioimmunoassay of testosterone

We report the evaluation of a commercial coated tube kit (Medgenix) to the measurement of testosterone in plasma/serum samples. The accuracy, precision, specificity and recovery of the assay and the affinity of antibody for ligand were established. The range of concentrations of testosterone providing satisfactory analyses was 0.48-48 nmol/l, which is appropriate for general clinical use. Results of analysis of male and female samples obtained from the routine hospital laboratory in endocrinologically-defined groups were also reviewed. In all groups of male subjects and in normal females, the kit provided results in close agreement to those of an extraction method. With samples from women with various reproductive disorders, as well as with some samples obtained from external quality controls, the kit showed a small but significant negative bias relative to the results of the extraction method. There was, however, no evidence of bias with samples from a separate group of volunteer women with the polycystic ovary syndrome. No interference due to SHBG was detected. Clinical sensitivities using the kit were equivalent to those obtained using the extraction RIA. There was no evidence of spuriously high results in samples from females which has been a common problem with direct radioimmunoassay of testosterone.

Diet and breast cancer

It is a general opinion that the Western diet plays a significant role in increasing the risk of breast cancer in the Western World. Recently some likely mechanisms involved in increasing the risk have been disclosed. It has been found that a Western-type diet elevates plasma levels of sex hormones and decreases the sex hormone binding globulin concentration, increasing the availability of these steroids for peripheral tissues. The same diet results in low formation by intestinal bacteria of mammalian lignans and isoflavonoid phyotestrogens from plant precursors. These diphenolic compounds seem to affect hormone metabolism and production and cancer cell growth by many different mechanisms making them strong candidates for a role as cancer protective substances. The sex hormone pattern found in connection with a Western-type diet combined with low lignan and isoflavonoid excretion was found particularly in postmenopausal breast cancer patients and omnivores living in high-risk areas, and to a lesser degree in areas with less risk. However, the pattern observed was not entirely due to diet.