High urinary phthalate concentration associated with delayed pubarche in girls

Phthalates are a group of chemicals present in numerous consumer products. They have anti-androgenic properties in experimental studies and are suspected to be involved in human male reproductive health problems. A few studies have shown associations between phthalate exposure and changes in pubertal timing among girls, although controversies exist. We determined the concentration of 12 phthalate metabolites in first morning urine samples from 725 healthy Danish girls (aged 5.6-19.1 years) in relation to age, pubertal development (breast and pubic hair stage) and reproductive hormone levels (luteinizing hormone, oestradiol and testosterone). Furthermore, urinary phthalates were determined in 25 girls with precocious puberty (PP). In general, the youngest girls with less advanced pubertal development had the highest first morning urinary concentration of the monobutyl phthalate isoforms (∑MBP((i+n))), monobenzyl phthalate (MBzP), metabolites of di-(2-ethylhexyl) phthalate (∑DEHPm) and of di-iso-nonyl phthalate (∑DINPm). After stratification of the urinary phthalate excretion into quartiles, we found that the age at pubarche was increasing with increasing phthalate metabolite quartiles (except for MEP). This trend was statistically significant when all phthalate metabolites (except MEP) were summarized and expressed as quartiles. No association between phthalates and breast development was observed. In addition, there were no differences in urinary phthalate metabolite levels between girls with PP and controls. We demonstrated that delayed pubarche, but not thelarche, was associated with high phthalate excretion in urine samples from 725 healthy school girls, which may suggest anti-androgenic actions of phthalates in our study group of girls.     

Causes of gynaecomastia in young adult males and factors associated with idiopathic gynaecomastia

Gynaecomastia is a common clinical condition. Persistent pubertal or late onset idiopathic gynaecomastia is the leading cause of gynaecomastia in different series. The aim of this study was the assessment of the prevalence and characteristics of different causes of gynaecomastia in young adult males, and evaluation of the factors associated with idiopathic gynaecomastia. Fifty-three male patients (mean age 22.04 +/- 2.22, range 19-29), who had been admitted to our outpatient clinics with gynaecomastia as the main presenting symptom were enrolled in the study. Patients were evaluated with breast palpation, breast ultrasonography, anthropometric measurements and sex steroid levels. Secondary causes of gynaecomastia were ruled out. Thirty age-matched healthy individuals were also studied as healthy control group. Idiopathic gynaecomastia was diagnosed in 31 of 53 patients (58%), with 17 (32%) persistent pubertal and 14 (24%) late onset course. Other causes of gynaecomastia were hypogonadism in 13 cases (25%), hyperprolactinaemia in five (9%), chronic liver disease in two (4%), and drug induced (prolonged use of H2 antagonists) in two (4%). Patients with idiopathic gynaecomastia, either pubertal or late onset, were compared with the healthy control group in order to find out associated factors. Anthropometric measurements revealed a significant increase in body weight and body mass index (BMI) in the patient group compared with healthy controls (72.4 +/- 13.3 vs. 63.6 +/- 7.9 kg, p = 0.0086 and 25.2 +/- 4.0 vs. 21.5 +/- 2.7 kg/m2, p = 0.0001). Total skin fold thickness (SFT) of four different regions were also higher in the patient group (50.9 +/- 22.1 vs. 32.6 +/- 10.2 mm, p = 0.0006) indicating a higher body fat percentage. Total serum testosterone (4.76 +/- 1.31 vs. 5.70 +/- 1.06 microg/mL, p = 0.0038) and luteinizing hormone (LH) (4.80 +/- 1.92 vs. 7.32 +/- 1.90 mIU/mL, p < 0.0001) levels were significantly lower in the patient group while oestradiol levels were similar. There was a significant correlation between total testosterone and LH levels (r = 0.27, p = 0.0445). Total testosterone and LH levels were negatively correlated with BMI and total SFT. As a result most common form of gynaecomastia is idiopathic gynaecomastia either as persistent pubertal or late onset forms in young adult males. Idiopathic gynaecomastia is closely correlated with generalized obesity, reduced LH and testosterone levels which may be the result of increased conversion of testosterone to oestradiol in increased adipose tissue mass.     

Possible impact of phthalates on infant reproductive health

Phthalates adversely affect the male reproductive system in animals, inducing hypospadias, cryptorchidism, reduced testosterone production and decreased sperm counts. Phthalate effects are much more severe after in utero than adult exposure. Little is known about human health effects. This study discusses two recent studies on perinatal phthalate exposure, which indicated that human testicular development might be susceptible to phthalates. One study analysed phthalate monoesters in breast milk and reproductive hormone levels in infants. Five of six phthalates [monoethyl-(MEP), monobutyl- (MBP), monomethyl- (MMP), mono-2-ethylhexyl- (MEHP) and mono-isononyl phthalate (MiNP)] showed correlation with hormone levels in healthy boys, which were indicative of lower androgen activity and reduced Leydig cell function. MEP and MBP were positively correlated with serum sex hormone-binding globulin (SHBG) levels. MMP, MEP, MBP, MEHP and MiNP were positively correlated with the LH/testosterone ratio. Another study found a reduction of the anogenital index (AGI) in infant boys with increasing levels of MBP, MEP, monobenzyl- and mono-isobutyl phthalate in maternal urine samples during late-pregnancy. Boys with small AGI showed a high prevalence of cryptorchidism and small genital size. Taken together these studies suggest an antivirilizing effect of phthalates in infants. Most of these findings are in line with animal observations. However, the possible effects of MEP appear to be limited to humans. This may be due to differences in exposure routes (inhalation and dermal absorption which circumvents liver detoxification in addition to oral) and metabolism, or this association could be spurious. As phthalates are produced as bulk chemicals worldwide, these new findings raise concern about the safety of phthalate exposure for pregnant women and infants.     

Phthalates: metabolism and exposure

Summary In human metabolism studies we found that after oral application of di(2-ethylhexyl) phthalate (DEHP), diisononyl phthalate (DiNP) and di(2-propylheptyl) phthalate (DPHP), at least 74, 44 and 34%, respectively, are excreted via urine. In contrast to the short chain phthalates, their oxidized products, not the simple monoesters, were found to be the main metabolites. Based on urinary phthalate metabolite concentrations we estimated in 102 German subjects between 6 and 80 years of age median daily intakes (μg/kg/day) of 2.7 for DEHP, 2.1 for di-n-butyl phthalate, 1.5 for diisobutyl phthalate, 0.6 for DiNP, and 0.3 for butylbenzyl phthalate. In general, children have higher exposures compared to adults and seem to have a more effective oxidative metabolism of phthalates. For individual phthalates tolerable daily intake (TDI) values have been deduced. However, in rats some phthalates have been shown to act as endocrine disrupters via a common mechanism of action in a dose-additive manner. Therefore, the concept of a cumulative TDI value may be more appropriate for the consideration of the overall exposure and the potential human health risks resulting from everyday and simultaneous exposure to several phthalates.     

Disruption of reproductive development in male rat offspring following in utero exposure to phthalate esters

Certain Phthalate esters have been shown to produce reproductive toxicity in male rodents with an age dependent sensitivity in effects with foetal animals being more sensitive than neonates which are in turn more sensitive than pubertal and adult animals. While the testicular effects of phthalates in rats have been known for more than 30 years, recent attention has been focused on the ability of these agents to produce effects on reproductive development in male offspring after in utero exposure. These esters and in particular di-butyl, di-(2-ethylhexyl) and butyl benzyl phthalates have been shown to produce a syndrome of reproductive abnormalities characterized by malformations of the epididymis, vas deferens, seminal vesicles, prostate, external genitalia (hypospadias), cryptorchidism and testicular injury together with permanent changes (feminization) in the retention of nipples/areolae (sexually dimorphic structures in rodents) and demasculinization of the growth of the perineum resulting in a reduced anogenital distance (AGD). Critical to the induction of these effects is a marked reduction in foetal testicular testosterone production at the critical window for the development of the reproductive tract normally under androgen control. A second Leydig cell product, insl3, is also significantly down regulated and is likely responsible for the cryptorchidism commonly seen in these phthalate-treated animals. The testosterone decrease is mediated by changes in gene expression of a number of enzymes and transport proteins involved in normal testosterone biosynthesis and transport in the foetal Leydig cell. Alterations in the foetal seminiferous cords are also noted after in utero phthalate treatment with the induction of multinucleate gonocytes that contribute to lowered spermatocyte numbers in postnatal animals. The phthalate syndrome of effects on reproductive development has parallels with the reported human testicular dysgenesis syndrome, although no cause and effect relationship exists after exposure of humans to phthalate esters. However humans are exposed to and produce the critical phthalate metabolites that have been detected in blood of the general population, in children and also human amniotic fluid.     

Urinary concentrations of di(2-ethylhexyl) phthalate metabolites and serum reproductive hormones: pooled analysis of fertile and infertile men

Urinary concentrations of metabolites of the anti-androgenic xenobiotic di-(2-ethylhexyl) phthalate (DEHP) were previously shown to be weakly associated with serum levels of several hormones in 2 disparate US populations: partners of pregnant women participating in the Study for Future Families and partners in infertile couples from Massachusetts General Hospital infertility clinic. The observed associations between phthalate metabolites and reproductive hormones were robust and insensitive to the characteristics of the subpopulation or the laboratory in which the hormones were measured, despite the fact that these 2 populations span a range of fertility, urinary phthalate metabolites, and reproductive hormone levels. We therefore examined associations between urinary metabolites of DEHP and reproductive hormones-follicle-stimulating hormone, luteinizing hormone, testosterone (T), inhibin B, and estradiol (E(2))-and sex hormone-binding globulin (SHBG) in the pooled population. The magnitude of the associations seen were similar to those reported for each population separately, but effect estimates were more precise because of the increased sample size and the greater range of phthalate metabolite concentrations and hormone levels. Urinary concentrations of 3 metabolites of DEHP [mono(2-ethylhexyl) phthalate (MEHP), mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), and mono(2-ethyl-5-oxohexyl) phthalate (MEOHP)] were inversely associated with the free androgen index (FAI = T/SHBG) and calculated free testosterone. Urinary concentrations of MEHHP and MEOHP were positively associated with SHBG, and MEHP was inversely associated with E(2). No other phthalate metabolites were associated with serum hormones, consistent with results in each population. Our results in this diverse population suggest that DEHP exposure is robustly associated with some male sex steroid hormones.     

Urinary excretion of phthalates and paraben after repeated whole-body topical application in humans

Diethyl phthalate (DEP), dibutyl phthalate (DBP) and butyl paraben (BP) are man-made chemicals used in personal care products, such as lotions and creams. Exposure to these chemicals causes a variety of adverse reproductive outcomes in animal studies. Humans can be exposed to these chemicals through dermal absorption, but there are no published data on absorption, metabolism, and excretion after dermal application. This study investigates urinary concentrations of BP and metabolites of DEP and DBP after topical application. In a 2-week single-blinded study, 26 healthy Caucasian male subjects were given a whole body topical application of basic cream 2 mg/cm(2) (control week) and then a cream containing 2% (w/w) of DEP, DBP and BP each (treatment week) daily. Twenty-four-hour urine samples were collected. Urinary total, and unconjugated BP, monoethyl phthalate (MEP) and monobutyl phthalate (MBP) metabolites were analysed by Liquid Chromatography-Tandem Mass Spectroscopy (LC-MS/MS). All 26 subjects showed increased excretion of MEP, MBP and BP following topical application. Total MEP, MBP and BP (mean +/- SEM) excreted in urine in the treatment week were, respectively, 41 +/- 1.9, 11.8 +/- 0.6 and 2.6 +/- 0.1 mg/24 h. On average 5.79, 1.82 and 0.32%, respectively, of the applied DEP, DBP and BP could be recovered in urine as MEP, MBP and BP. The concentration of the compounds peaked in urine 8-12 h after application. The fractions of unconjugated MEP, MBP, and BP were 78, 8.0 and 2.1%, respectively. Absorption of DEP, DBP and BP through skin could potentially contribute to adverse health effects. The three chemicals are systemically absorbed, metabolized and excreted in urine following application on the skin in a cream preparation. More DEP than DBP was absorbed, presumably because of a faster absorption rate for DEP.     

The relationship between environmental exposure to phthalates and computer-aided sperm analysis motion parameters

The general population is exposed to phthalates through consumer products, diet, and medical devices. The present study explored whether phthalates, reproductive toxins in laboratory animals, were associated with altered sperm movement characteristics in men. Two-hundred twenty subjects provided a semen sample for computer-aided sperm analysis (CASA) and a urine sample for measurement of phthalate monoesters, monoethyl (MEP), monobenzyl (MBzP), mono-n-butyl (MBP), mono-2-ethylhexyl (MEHP), and monomethyl (MMP). Three CASA parameters, straight-line velocity (VSL), curvilinear velocity (VCL), and linearity (LIN), were used as measures of sperm progression, sperm vigor, and swimming pattern, respectively. There were suggestive dose-response relationships (shown as the predicted change in mean sperm motion parameter for the second and third tertiles compared with the first tertile; P value for trend) for MBzP with VSL (-2.36 microm/s, -2.81 microm/s; P =.09) and VCL (-1.67 microm/s, -2.45 microm/s; P =.4). There were suggestive negative associations between MBP and VSL (-3.07 microm/s, -2.87 microm/s; P =.08) and VCL (-3.25 microm/s, -3.46 microm/s; P =.2), and between MEHP with VSL (-1.09 microm/s, -2.73 microm/s; P =.1) and VCL (-0.29 microm/s, -2.93 microm/s; P =.3). In contrast to the other phthalates, MEP was positively associated with VSL and VCL but negatively associated with LIN. No consistent relationship was found for MMP and any sperm motion parameter. Although we did not find statistically significant associations, trends between CASA parameters, sperm velocity, and forward progression, and increased urinary levels of MBP, MBzP, and MEHP warrant further follow-up.     

Pubertal development in Danish children: comparison of recent European and US data

Two recent epidemiological studies (PROS and NHANES III) from the USA noted earlier sexual maturation in girls, leading to increased attention internationally to the age at onset of puberty. We studied the timing of puberty in a large cohort of healthy Danish children in order to evaluate differences between USA and Denmark, as well as to look for possible secular trends in pubertal development. Healthy Caucasian children from public schools in Denmark participated in the study which was carried out in 1991-1993. A total number of 826 boys and 1,100 girls (aged 6.0-19.9 years) were included, and pubertal stages were assessed by clinical examination according to methods of Tanner. In boys testicular volume was determined using an orchidometer. We found that age at breast development 2 (B2) was 10.88 years, and mean menarcheal age was 13.42 years. Girls with body mass index (BMI) above the median had significantly earlier puberty (age at B2 10.42 years) compared with girls with BMI below the median (age at B2 11.24 years, p < 0.0001). Similarly, menarcheal age was significantly lower in girls with BMI above the median compared with girls with BMI below the median (13.12 vs. 13.70 years, p = 0.0012). In Danish boys we found that age at genital stage 2 (G2) was 11.83 years. Both sexes were significantly taller compared with data from 1964, but timing of pubertal maturation seemed unaltered. Finally, puberty occurred much later in Denmark compared with recent data from USA. We could not detect any downwards secular trend in the timing of puberty in Denmark between 1964 and 1991-1993 as seen in the US. Obesity certainly plays a role in the timing of puberty, but the marked differences between Denmark and USA cannot be attributed exclusively to differences in BMI. A possible role of other factors like genetic polymorphisms, nutrition, physical activity or endocrine disrupting chemicals must therefore also be considered. Therefore, we believe it is crucial to monitor the pubertal development closely in Denmark in the coming decades.     

The clinical relevance of sex hormone levels and sexual activity in the ageing male

OBJECTIVES: To assess the changes in sex hormone levels with age and the relationship of sexual functioning to testosterone levels, evaluating serum testosterone levels and erectile function in men with lower urinary tract symptoms (LUTS). PATIENTS AND METHODS: The study included 213 men with LUTS (age range 31-78 years) who had no confirmed erectile dysfunction. Their serum total and free testosterone, and sex-hormone binding globulin (SHBG) levels were measured, and they completed the International Index of Erectile Function (IIEF) questionnaire. RESULTS: The total and free testosterone levels decreased and SHBG increased with age, but only the change in free testosterone and SHBG were statistically significant. The correlation with age was closer for free testosterone (r = - 0.356, P < 0.001) than for SHBG (r = 0.177, P = 0.010). Regression analysis of the five domain scores of the IIEF and three hormonal levels, after correcting for age, showed that free testosterone level was significantly correlated with erectile function (r = 0.2136, P = 0.005) and orgasmic function (r = 0.179, P = 0.020), but SHBG levels were significantly correlated only with orgasmic function (r = - 0.154, P = 0.046). Total testosterone levels showed no significant correlation with any of the five domains of the IIEF. CONCLUSIONS: Of the sex hormone levels, the change in free testosterone correlated most closely with ageing and had the closest correlation with sexual activity. Contrary to previous reports, free testosterone and SHBG levels were significantly correlated with orgasmic function and/or erectile function rather than sexual desire. A complete study of sex hormone levels is needed to evaluate patients with erectile dysfunction.     

Biphasic effects of postnatal exposure to diethylhexylphthalate on the timing of puberty in male rats

Phthalate esters such as di(2-ethylhexyl)phthalate (DEHP), which are commonly found in cosmetics and in flexible plastics distributed by the food, construction, and medical products industries, have been classified as anti-androgens. High-dose DEHP exposure in utero is associated with decreased androgen levels. However, when administered after birth, low doses of DEHP (eg, 10 mg/kg body weight) may stimulate androgen production. In the present study, the potential of phthalate exposure to advance or delay the timing of puberty was assessed. Male Long-Evans rat pups were chronically subjected to low or high doses of DEHP, with the androgen-driven process of preputial separation serving as an index of pubertal timing. Rats were treated with 0, 10, 500, or 750 mg/kg body weight DEHP for 28 days starting at day 21 postpartum. The average age at which the animals completed preputial separation was measured in each group. The age of preputial separation was 41.5 +/- 0.1 days postpartum in controls (vehicle). The 10 mg/kg DEHP dose advanced pubertal onset significantly to 39.7 +/- 0.1 days postpartum, whereas the 750 mg/kg DEHP dose delayed pubertal onset to 46.3 +/- 0.1 days postpartum. The 10 mg/kg DEHP dose also significantly increased serum testosterone (T) levels (3.13 +/- 0.37 ng/mL) and seminal vesicle weights (0.33 +/- 0.02 g) compared with control serum T (1.98 +/- 0.20 ng/mL) and seminal vesicle weight (0.26 +/- 0.02 g), while the 750 mg/kg dose decreased serum T (1.18 +/- 0.18 ng/mL) as well as testes and body weights. Direct action of the DEHP metabolite, monoethylhexylphthalate (MEHP), on Leydig cell steroidogenic capacity was investigated in vitro. MEHP treatment at a low concentration (100 microM) increased luteinizing hormone-stimulated T production, whereas 10 mM concentrations were inhibitory. In conclusion, data from the present study indicate that DEHP has a biphasic effect on Leydig cell function, with low-dose exposure advancing the onset of puberty. High doses of DEHP, which are anti-androgenic, may also be outside the range of real environmental exposure levels.     

The influence of serum ghrelin,IGF axis and testosterone on bone mineral density in boys at different stages of sexual maturity

The aim of our study was to examine the relationship between bone mineral density (BMD) and serum ghrelin, insulin-like growth factor-1 (IGF-1), IGF-binding protein 3 (IGFBP-3), and testosterone levels in boys at different stages of puberty. The study included 60 healthy nonobese Estonian schoolboys at the age of 10–18 years. Subjects were divided in three groups (20 boys in each) based on the results of self-assessment using illustrated questionnaire of pubertal stage (G1, I; G2–G3, II; G3–G4, III). Morning fasting blood samples were collected for analysis of ghrelin, testosterone, IGF-1, and IGFBP-3. Total body BMD, lumbar BMD, lumbar apparent volumetric BMD (BMAD), and bone mineral content (BMC) were measured by DXA. Serum testosterone concentration was the most important biochemical predictor of BMD in the total group, explaining 48.8% of variability in total body BMD, 51.4% in lumbar BMD, and 36.8% in lumbar BMAD. Body mass and height were both related to BMD and BMC throughout puberty. The serum IGF-1/IGFBP-3 ratio was correlated with serum testosterone (r = 0.69) and ghrelin (r = −0.58) levels, but also with total BMD (r = 0.39), lumbar BMD (r = 0.42; P < 0.001 in all cases), BMAD (r = 0.29; P < 0.01), and total BMC (r = 0.48; P < 0.001). We conclude that serum testosterone concentration and serum IGF-1/IGFBP-3 molar ratio are the major determinants of bone mineral density in boys at different pubertal stages. Serum ghrelin concentration did not appear to have a direct independent effect on BMD. If present, the association may be mediated through sex hormones and the GH-IGF-I axis.     

Urinary excretion of retinol-binding protein in healthy children and adolescents

Retinol-binding protein (RBP) is a marker of tubular reabsorption in the kidneys. The aim of our study was to investigate urinary RBP excretion in healthy children to obtain reference values related to age and pubertal stage. Overnight samples from 143 subjects (73 girls, 70 boys) aged 10–18 years were investigated. RBP was quantified by a solid-phase sandwich enzyme immunoassay. Both the RBP excretion rate and the RBP/ creatinine ratio (RBP/Cr) showed a skewed distribution. The medians and the 5th–95th percentiles were 38 ng/min (15–127) and 9 μg/mmol (4–23), respectively. The RBP excretion rate and RBP/Cr ratio were similar in both sexes, and linear multiple regression analysis showed no association with age or pubertal stage, although a weak relationship (r = 0.27) was found between RBP excretion rate and age in boys and RBP/Cr ratio and age (r = -0.28) in girls by simple correlation analysis. The correlation between RBP excretion rate and RBP/Cr ratio was 0.76; the RBP excretion rate and RBP/Cr ratio measured on 2 consecutive days, showed a correlation coefficient of 0.84 and 0.88, respectively. We conclude that overnight RBP excretion in children over 10 years shows a low day-to-day variation and, in practical terms, is independent of age, gender and pubertal stage.     

A study on the effect of phthalate esters and their metabolites on idiopathic infertile males

Phthalate plasticisers in medical, cosmetic and consumer products might pose serious health implications in humans including infertility. We sought to investigate the correlation, if any, between the phthalates and their metabolites and sperm quality parameters, and male infertility. Phthalate esters (15) and their metabolites (5) were estimated in the blood serum and urine samples from the age-matched 152 infertile and 75 fertile males using gas chromatography (GC) and high-performance liquid chromatography (HPLC). Finally, the data were analysed to correlate phthalate exposure and semen quality parameters in the infertility group. The estimated levels of DEHP, DBP, DIBP, BEHIP, BPBG, DPP, DIOP, DIHP, DMP, DINP, BIOP, DMOP and DICHP were significantly higher in the infertile males compared to the fertile males (p < .05 or p < .01). However, these were not found to be associated with the semen quality parameters (sperm count, motility and sperm morphology). Similarly, HPLC data revealed that the associations between semen parameters (sperm count, sperm motility and sperm morphology) and phthalate metabolite (MEHP and MBP) concentrations in urine samples from the infertile males were mostly unremarkable or statistically nonsignificant. Conclusively, environmental exposure to phthalates and their impacts on male infertility were statistically insignificant in our study groups.     

Effect of urinary bilharzial infection on male pubertal development and endocrine functions

One hundred seventy-five males aged 9-20 years were selected. The subjects comprised two groups; controls and patients infected with urinary bilharziasis not associated with any other parasite. Pubertal development was assessed. Serum levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone, and progesterone were determined by radioimmunoassay procedure. Delay in pubertal development was evident in the normal control group as indicated by higher chronological age mean values at the various stages as compared to other world norms. Urinary bilharziasis exaggerated the delay in pubertal development as compared to that in the control group. In relation to the control group, the group with urinary bilharziasis had higher levels of serum FSH and LH, which were significant only at stages III and IV. No significant difference was noted between the two groups for serum testosterone and progesterone levels, except for the high progesterone mean value at stage V in the group with urinary bilharziasis.     

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.     

The relationships between pubertal development, IGF-1 axis, and bone formation in healthy adolescents

As IGF-1 is the major factor that affects bone growth, and both osteocalcin and bone-specific alkaline phosphatase are important markers of bone formation during puberty, there must be a relationship between these markers that does not change according to sex. The aim of this study was to investigate the relationships between pubertal development, the IGF-1 axis, and bone formation in healthy adolescents. Two hundred and five healthy children and adolescents were included in this cross-sectional study. Tanners classification was used to determine the pubertal developmental stage. Serum IGF-1 levels and IGF-1/IGFBP-3 ratios increased with advancing pubertal stages, and maximum mean values were found at stages III–IV in girls and at stage IV in boys. Serum IGF-1 and IGFBP-3 levels were significantly correlated with osteocalcin and bone-specific alkaline phosphatase levels in boys, but not in girls. This difference between the sexes, and the relation of the IGF-1 axis to increased bone formation during puberty in both sexes, can be explained by the rate of increase of the IGF-1/IGFBP-3 ratio. We conclude that the timing of the increased bone formation rate during puberty; that is, the timing of the pubertal growth spurt, is determined by the maximum increase rate of the IGF-1/IGFBP-3 ratio. But this new hypothesis needs to be supported by longitudinal studies.     

The oxidative metabolism of estradiol conditions postmenopausal bone density and bone loss.

Because lifelong exposure to estrogen is a strong determinant of bone mass, we asked whether metabolic conversion of estrogen to either inactive or active metabolites would reflect postmenopausal bone mineral density (BMD) and rate of bone loss. Biochemical markers of inactive estrogen metabolites, urinary 2-hydroxyestrogen (2OHE1) and 2-methoxyestrogen (2MeOE1), and active metabolites, urinary 16alpha-hydroxyestrone (16alphaOHE1), estradiol (E2), and estriol (E3), were determined in 71 untreated, healthy postmenopausal women (age, 47-59 years) followed prospectively for 1 year. Urinary 2MeOE1 was correlated negatively with baseline vertebral (anteroposterior [AP] projection, r = -0.23 andp < 0.05; lateral view, r = -0.27 and p < 0.05) and proximal femur bone density measured by dual-energy X-ray absorptiometry (DXA; total, r = -0.38 and p < 0.01; neck, r = -0.28 and p = 0.02; trochanter, r = -0.44 and p < 0.01). BMDs of women in the lowest quartile of urinary 2MeOE1 (< 15 ng/g) were significantly higher than those in the highest quartile at all skeletal sites (p < 0.05). Likewise, women in the lowest quartile of urinary 2OHE1/16alphaOHE1 ratio (< 1.6) did not experience bone loss after 1 year, in contrast to women in the higher quartiles. We propose that the rate of inactivation of estrogens through 2-hydroxylation may contribute to postmenopausal osteoporosis.     

Influence of ageing and some lifestyle factors on male gonadal function: a study in Bulgaria

There are few systematic studies on the relationship between blood testosterone concentrations and the symptoms of androgen deficiency in ageing males. To assess the changes in sex hormone levels with age in relation with some lifestyle factors, the serum levels of total testosterone (TT), sex-hormone binding globulin (SHBG), luteinising hormone (LH) and follicle stimulating hormone (FSH) were measured in 33 men, age range 40-89 years. In addition, free testosterone (FT) and the free androgen index (FAI) were calculated. Seventeen healthy men under 40 years were involved as controls. The men over 40 years revealed significantly decreased TT, FT and FAI, and in the subgroup of men over 60 years, FSH and SHBG were significantly increased. Pearson's analysis showed that TT levels were significantly correlated with body mass index (BMI) (r = -0.464, P < 0.01) and body weight (r = -0.413, P < 0.05). SHBG levels were significantly correlated not only with age (r = +0.407, P < 0.05), but also with LH (r = +0.605, P < 0.001) and alcohol consumption (r = +0.382, P < 0.05). In conclusion, the TT, FT and FAI decreased in males over 40 years, but the alterations in hormone levels with age are more pronounced in men over 60 years. The important determinants of sex hormones are age, BMI and some lifestyle factors.     

Relation of adrenal-derived steroids with bone maturation,mineral density and geometry in healthy prepubertal and early pubertal boys

BackgroundLittle is known about the effects of adrenal steroids on skeletal maturation and bone mass acquisition in healthy prepubertal boys.ObjectiveTo study whether adrenal-derived steroids within the physiological range are associated with skeletal maturation, areal and volumetric bone mineral density (aBMD and vBMD) and bone geometry in healthy prepubertal and early pubertal boys.Methods98 healthy prepubertal and early pubertal boys (aged 6–14 y) were studied cross-sectionally. Androstenedione (A) and estrone (E1) were determined by liquid chromatography tandem mass spectrometry and DHEAS was determined by immunoassay. Whole body and lumbar spine aBMD and bone area were determined by dual-energy X-ray absorptiometry. Trabecular (distal site) and cortical (proximal site) vBMD and bone geometry were assessed at the non-dominant forearm and leg using peripheral QCT. Skeletal age was determined by X-ray of the left hand.ResultsAdrenal-derived steroids (DHEAS, A and E1) are positively associated with bone age in prepubertal and early pubertal children, independently of age. There are no associations between the adrenal-derived steroids and the studied parameters of bone size (lumbar spine and whole body bone area, trabecular or cortical area at the radius or tibia, periosteal circumference and cortical thickness at the radius or tibia) or BMD (aBMD or vBMD).ConclusionIn healthy prepubertal and early pubertal boys, serum adrenal-derived steroid levels, are associated with skeletal maturation, independently of age, but not with bone size or (v)BMD. Our data suggest that adrenal derived steroids are not implicated in the accretion of bone mass before puberty in boys.