Factors related to sex hormone binding globulin concentrations in women with anorexia nervosa

Disturbances in gonadal axis in women with anorexia nervosa

Anorexia nervosa negatively affects multiple body systems including the reproductive system.

AIM

To assess the disturbances in the hypothalamic-pituitary-gonadal axis (HPG) and the relationship between the gonadotropins and body weight, duration of the disease and amenorrhea we studied 40 female anorexic patients (aged 14-31 years) with a body mass index (BMI) 15.14+/-1.80 kg/m(2) and a degree of weight loss 28.67+/-8.74%. Fifteen healthy, age-matched women with normal weight served as controls.

METHODS

We investigated the disturbances in the gonadotropin levels before and after stimulation with gonadotropin-releasing hormone (GnRH) 100 microg i.v. One week later 100 mg of clomiphene citrate (CC) was administered orally for 5 days.

RESULTS

Basal levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were significantly lower in the patients. The responses of LH to GnRH were diminished, but those of FSH were exaggerated. However, after clomiphene citrate administration, LH increased 5.4 times whereas FSH increased 1.7 times. The basal levels of LH were significantly correlated with body weight (r=+0.373, p<0.05), BMI (r=+0.385, p<0.01) and percentage of the weight loss (r=-0.356, p<0.05). FSH levels were positively correlated with the duration of the disease (r=+0.481, p<0.01) and amenorrhea (r=+0.540, p<0.01).

CONCLUSIONS

Our study demonstrates dissociation in the secretion of gonadotropins after hypothalamic stimulation in anorexic patients. It also reveals the relationship between alterations in the hormones of the HPG axis, not only with the changes in body weight, but also with the duration of the disease.

Androgens in women with anorexia nervosa and normal-weight women with hypothalamic amenorrhea

CONTEXT

Anorexia nervosa and normal-weight hypothalamic amenorrhea are characterized by hypogonadism and hypercortisolemia. However, it is not known whether these endocrine abnormalities result in reductions in adrenal and/ or ovarian androgens or androgen precursors in such women, nor is it known whether relative androgen deficiency contributes to abnormalities in bone density and body composition in this population.

OBJECTIVE

Our objective was to determine whether endogenous androgen and dehydroepiandrosterone sulfate (DHEAS) levels: 1) are reduced in women with anorexia nervosa and normal-weight hypothalamic amenorrhea, 2) are reduced further by oral contraceptives in women with anorexia nervosa, and 3) are predictors of weight, body composition, or bone density in such women.

DESIGN AND SETTING

We conducted a cross-sectional study at a general clinical research center.

STUDY PARTICIPANTS

A total of 217 women were studied: 137 women with anorexia nervosa not receiving oral contraceptives, 32 women with anorexia nervosa receiving oral contraceptives, 21 normal-weight women with hypothalamic amenorrhea, and 27 healthy eumenorrheic controls.

MAIN OUTCOME MEASURES

Testosterone, free testosterone, DHEAS, bone density, fat-free mass, and fat mass were assessed.

RESULTS

Endogenous total and free testosterone, but not DHEAS, were lower in women with anorexia nervosa than in controls. More marked reductions in both free testosterone and DHEAS were observed in women with anorexia nervosa receiving oral contraceptives. In contrast, normal-weight women with hypothalamic amenorrhea had normal androgen and DHEAS levels. Lower free testosterone, total testosterone, and DHEAS levels predicted lower bone density at most skeletal sites measured, and free testosterone was positively associated with fat-free mass.

CONCLUSIONS

Androgen levels are low, appear to be even further reduced by oral contraceptive use, and are predictors of bone density and fat-free mass in women with anorexia nervosa. Interventional studies are needed to confirm these findings and determine whether oral contraceptive use, mediated by reductions in endogenous androgen levels, is deleterious to skeletal health in such women.

Serum concentrations of sex hormone binding globulin are elevated in kwashiorkor and anorexia nervosa but not in marasmus

BACKGROUND

Customary blood protein markers for malnutrition are of limited value in the diagnosis of protein-energy malnutrition or anorexia nervosa in children and in the follow-up to refeeding in such children.

OBJECTIVES

For these diseases, we compared the diagnostic value of sex hormone binding globulin (SHBG) with that of albumin, transferrin, transthyretin, and retinal binding protein and determined the relations between concentrations of insulin, insulin-like growth factor I, and SHBG.

DESIGN

SHBG was assayed in children with protein-energy malnutrition (29 children with kwashiorkor and 28 with marasmus), in 29 anorectic girls (before and after refeeding), and in age- and sex-matched control subjects.

RESULTS

Mean (+/-SE) serum SHBG concentrations were higher in the children with kwashiorkor (0.18 +/- 0.07 micromol/L) than in the children with marasmus (0.11 +/- 0.05 micromol/L, P < 0.0001) or the control subjects (0.11 +/- 0.03 micromol/L, P < 0.0005). In the children with anorexia nervosa before weight gain, serum SHBG concentrations were significantly higher (0.10 +/- 0.04 micromol/L) than in the age-matched control subjects (0.06 +/- 0.03 micromol/L, P < 0.001) and decreased significantly after 30 d of refeeding (0.04 +/- 0.01 micromol/L, P < 0.0001). This decrease was negatively correlated with insulin-like growth factor I but not with insulin. Mean serum SHBG concentrations were influenced neither by inflammation, as indicated when C-reactive protein was used as a marker (0.27 +/- 0.27, 0.34 +/- 0.42, and <0.04 micromol/L in the children with marasmus, kwashiorkor, and anorexia nervosa, respectively), nor by glomerular filtration, as indicated when cystatin-C was used as a marker (68.46 +/- 23.08, 66.90 +/- 43.08, and 49.23 +/- 7.69 micromol/L, respectively).

CONCLUSIONS

The high SHBG concentration observed in anorexia nervosa and kwashiorkor seems to be of multifactorial origin. For these 2 diseases, SHBG is a reliable marker of nutritional status, is unrelated to either C-reactive protein or cystatin-C, and may be helpful in distinguishing kwashiorkor from marasmus and as a follow-up marker after refeeding.

Population differences in the pattern of familial aggregation for sex hormone-binding globulin and its response to exercise training: the HERITAGE Family Study

Familial influences were investigated for baseline sex hormone-binding globulin (SHBG) and its response (post-training minus baseline) to a 20-week endurance exercise training program. One hundred, eighty-four participants from 85 Black families in the HERITAGE Family Study (HERITAGE) were analyzed using a familial correlation model. Baseline SHBG values and the training response were adjusted for the effects of age, baseline BMI, testosterone, estradiol, and fasting insulin levels (plus baseline SHBG values for the training response) within four sex-by-generation groups prior to genetic analysis. Baseline SHBG levels were influenced by appreciable familial effects (maximum heritability h(2) = 54%) with neither spouse resemblance nor sex and generation differences in the correlations. This estimate is only slightly, but not significantly, smaller than the heritability of 64% reported previously in 428 participants from 99 White families in HERITAGE. In contrast to the modest familial effects for the training response in White participants in HERITAGE (h(2) = 25%), there were no evidence of familial resemblance in Blacks in the current study. Furthermore, there was heterogeneity for both baseline SHBG and the training response between Blacks and Whites in the pattern of familial aggregation. In conclusion, baseline SHBG levels are influenced by significant familial effects in both Blacks and Whites, independent of the effects of age, sex, and baseline values of BMI, testosterone, estradiol, and fasting insulin levels. Whereas modest familial effects were detected for the training response in Whites, the lack of similar effects in Blacks may be due to the smaller sample size.

The relationship between thyroxine, oestradiol, and postnatal alopecia, with relevance to women's health in general

Post-partum hair loss is possibly due to a reduction in the levels of oestradiol and thyroxine postnatally. Alopecia and/or a persistent loss of hair condition postnatally is associated with a group of symptoms (a syndrome), wherein postnatal depression is significant, as a result of physiologically inadequate levels of thyroxine (T4) and oestradiol (E2), secondary to physiological postnatal anterior pituitary dysfunction. Using this hypothesis, the author began to apply the same hypothesis to other female patients, who were not postpartum, but with similar symptomatology. The author became aware of the necessity for an adequate level of T4 to be present for correct oestrogenization to occur. He then goes on to hypothesize on the synergistic relationship that T4 and oestradiol may have in premenstrual syndrome (PMS), infertility, dysfunctional uterine bleeding, poor placental function, osteoporosis, and anorexia nervosa. He also discusses the role lowering T4 could play in the treatment of terminal cancer breast in premenopausal women.

Sex differences and similarities of hormonal alterations in patients with anorexia nervosa

The aim of the present study was to gain better insight into hormonal disturbances in male patients with anorexia nervosa. It included six men with anorexia nervosa aged 13-26 years, with a mean body weight of 42.83 +/- 8.03 kg, a body mass index of 15.08 +/- 1.26 and an average degree of weight loss 29.98 +/- 4.73%. The results were compared with those of 15 healthy age-matched males and 40 women with anorexia nervosa. Prolactin, growth hormone and the gonadal and thyroid axis were studied in detail. The gonadotropin basal levels and their responses to gonadotropin-releasing hormone in male patients were lower, but not significantly, in comparison with healthy men. The basal levels and the responses of luteinizing hormone in anorexic women were significantly lower in comparison with female controls, but the decreased basal level of follicle-stimulating hormone showed an exaggerated response to gonadotropin-releasing hormone. In male anorexics the testosterone levels (7.1 +/- 10.9 nmol l-1) were significantly lower. The changes in the thyroid axis and in prolactin secretion were almost the same in male and female patients. The data of this study suggest that endocrine disturbances in males are similar to those in females with anorexia nervosa, but differences exist mainly in relation to the gonadal axis.

Quantitative genetics of serum sex hormone-binding globulin levels in participants in the San Antonio Family Heart Study

Sex hormone-binding globulin (SHBG) is a steroid-binding plasma protein with a high affinity for testosterone that has been inversely associated with cardiovascular disease risk in many populations. SHBG may also act as a receptor in some tissues. Although the function of SHBG is relatively well understood, comparatively little is known about genetic factors contributing to the normal variation of serum SHBG levels. We estimated the heritability (h2) of serum SHBG levels in 717 related Mexican-Americans participating in the San Antonio Family Heart Study (SAFHS). We found a significant heritability (h2 = 0.31, P < .0001) for serum SHBG levels; age, exogenous hormones, smoking status, diabetic status, and adiposity showed significant associations (P < .05) with mean levels of SHBG. Sex was associated with mean SHBG levels but not with genetic or environmental variance in SHBG levels; heritability estimates were the same for males and females. These results indicate a significant genetic influence on SHBG in Mexican-Americans. Thus, SHBG may prove to be an important indicator of genetic risk for cardiovascular disease in this population, as well as others.