Boonsong Ongphiphadhanakul

Serum oestradiol and oestrogen‐receptor gene polymorphism are associated with bone mineral density independently of serum testosterone in normal males

The physiological effects of oestrogens on bone in men were largely unanticipated until recently, when oestrogen deficiency in males with aromatase deficiency and oestrogen resistance was found to cause osteoporosis and delayed fusion of epiphyses despite sufficient serum testosterone. This raises the possibility that in normal men oestrogens rather than androgens are of physiological importance in bone maturation. In the present study, we examined the association of serum oestradiol (E2) compared to that of free testosterone (FT) with bone mineral density (BMD) in normal men. The effect of oestrogen receptor (ER) gene polymorphism on BMD in men was also addressed.

Oestrogen-receptor-α gene polymorphism affects response in bone mineral density to oestrogen in post-menopausal women

An oestrogen‐receptor‐α (ERα) gene polymorphism has been variably reported to be related to bone mass. To investigate whether this ERα gene polymorphism is associated with a functional difference, we assessed the response in bone mineral density (BMD) to oestrogen therapy in post‐menopausal women in relation to ERα gene polymorphism.

Estrogen receptor gene polymorphism is associated with bone mineral density in premenopausal women but not in postmenopausal women

In the present study, we examined the genotypes distribution of Pvu II estrogen receptor (ER) gene polymorphism and its association to bone mass in Thai females. Subjects consisted of 134 Thai females 54 of whom were premenopausal and 80 were postmenopausal. Pvu II ER gene polymorphism was determined by PCR-RFLP. Capital P represents the absence of the restriction site while small p indicates the presence of the restriction site. Forty nine (36.6%) of the subjects had pp genotype, while 59 (44.0%) had Pp genotype and 26 (19.4%) had PP genotype. There was no significant difference in age, body weight, height and calcium intake in premenopausal women with different genotypes. The results including years since menopause were similar in postmenopausal women. When including ER gene genotypes, age, body weight, height and dietary calcium intake in a stepwise multiple regression model, it was found that besides body weight ER gene polymorphism was associated with bone mineral density (BMD) at AP spine (p<0.05), lateral spine (p<0.05) femoral neck (p<0.05) and femoral trochanter (p<0.05) with the pp genotype having the least BMD. ER gene polymorphism was the only factor associated with BMD at Ward’s triangle, (p<0.05) while only body weight was associated with BMD at distal and mid radius. There was no difference in serum intact osteocalcin (OC) concentrations among subjects with different genotypes. ER gene polymorphism was not related to BMD in postmenopausal women at any skeletal site. Similarly, serum intact OC levels were not different among postmenopausal women with different genotypes. We concluded that Pvu II estrogen receptor gene polymorphism is associated with bone mineral density in premenopausal women but not in postmenopausal women. Estrogen receptor gene polymorphism may have a modulatory role in calcium and bone metabolism during adolescence and young adulthood.

Serum testosterone and its relation to bone mineral density and body composition in normal males

OBJECTIVE Bone mineral density (BMD) declines with age in both men and women, predisposing the elderly to osteoporosis and fractures. Although there are extensive data about post‐menopausal osteoporosis, there is relatively little information concerning the decrease in BMD with age in normal men, particularly the contribution of declining gonadal function with age to BMD. In the present study, we investigated the effect of age on the pituitary‐gonadal axis in normal males and its relation to BMD and body composition.

Regional variation and determinants of vitamin D status in sunshine-abundant Thailand

BackgroundVitamin D insufficiency is highly prevalent. Most of the studies concerning vitamin D status were generated from countries situated at temperate latitudes. It is less clear what the extent of vitamin D insufficiency is in countries situated in the tropics and how geographical regions within country would affect vitamin D status. In the present study, we investigated vitamin D status in Thais according to geographical regions and other risk factors.MethodsSubjects consisted of 2,641 adults, aged 15 - 98 years, randomly selected from the Thai 4th National Health Examination Survey (2008-9) cohort. Serum 25 hydroxyvitamin D were measured by liquid chromatography/tandem mass spectrometry. Data were expressed as mean ± SE.ResultsSubjects residing in Bangkok, the capital city of Thailand, had lower 25(OH)D levels than other parts of the country (Bangkok, central, northern, northeastern and southern regions: 64.8 ± 0.7, 79.5 ± 1.1, 81.7 ± 1.2, 82.2 ± 0.8 and 78.3 ± 1.3 nmol/L, respectively; p < 0.001). Within each region, except for the northeastern part of the country, subjects living inside municipal areas had lower circulating 25(OH)D (central, 77.0 ± 20.9 nmol/L vs 85.0 ± 22.1 nmol/L, p < 0.001; north 79.3 ± 22.1 nmol/L vs 86.8 ± 21.8 nmol/L, p < 0.001; northeast 84.1 ± 23.3 nmol/L vs 87.3 ± 20.9 nmol/L, p = 0.001; south, 76.6 ± 20.5 nmol/L vs 85.2 ± 24.7 nmol/L, p < 0.001). Overall, the prevalence of vitamin D insufficiency was 64.6%, 46.7%, and 33.5% in Bangkok, municipal areas except Bangkok, and outside municipal area in other parts of the country, respectively. In addition, the prevalence of vitamin D insufficiency according to geographical regions was 43.1%, 39.1%, 34.2% and 43.8% in the central, north, northeast and south, respectively. After controlling for covariates in multiple linear regression analysis, the results showed that low serum 25(OH)D levels were associated with being female, younger age, living in urban and Bangkok.ConclusionsVitamin D insufficiency is common and varies across geographical regions in Thailand.

The effects of oestrogen exposure on bone mass in male to female transsexuals

The importance of oestrogen on bone mineral density (BMD) in males was suggested by reports of patients with oestrogen resistance and aromatase deficiency who demonstrated osteoporosis and epiphyseal plate maturation defect despite high testosterone levels. In the present study, we examined the effects of oestrogen exposure on BMD in transsexual men.

A reduced serum level of total osteocalcin in men predicts the development of diabetes in a long‐term follow‐up cohort

Background  Osteocalcin (OC), an osteoblast‐specific protein, has been demonstrated to affect glucose metabolism in both animals and humans. Studies in animals have shown an effect of undercarboxylated OC (ucOC) on beta‐cell proliferation and insulin resistance. It remains unclear whether OC is associated with the future development of diabetes in humans, as well as the relative importance of ucOC vs OC.

Changes in circulating 25-hydroxyvitamin D according to vitamin D binding protein genotypes after vitamin D3 or D2supplementation

BackgroundIt is not known whether genetic variation in the vitamin D binding protein (DBP) influences 25-hydroxyvitamin D levels [25(OH)D] after vitamin D supplementation. We aimed to investigate the changes of total 25(OH)D, 25(OH)D3 and 25(OH)D2 in a Thai cohort, according to type of vitamin D supplement (vitamin D3 or D2) and DBP genotype, after receiving vitamin D3 or D2 for 3 months.MethodsThirty-nine healthy subjects completed the study. All subjects received 400 IU of either vitamin D3 or D2, plus a calcium supplement, every day for 3 months. Total serum 25(OH)D, 25(OH)D3 and 25(OH)D2 were measured by LC-MS/MS. Individual genotyping of rs4588 in the DBP gene was performed using real-time PCR.ResultsVitamin D3 supplementation of 400 IU/d increased 25(OH)D3 significantly (+16.2 ± 4.2 nmol/L, p <0.001). Vitamin D2 (400 IU/d) caused increased 25(OH)D2 levels (+22.0 ± 2.11 nmol/L, p <0.001), together with a decrease of 25(OH)D3 (−14.2 ± 2.0 nmol/L, p <0.001). At 3 month, subjects in vitamin D3 group tended to have higher total 25(OH)D levels than those in vitamin D2 (67.8 ± 3.9 vs. 61.0 ± 3.0 nmol/L; p = 0.08). Subjects were then classified into two subgroups: homozygous for the DBP rs4588 C allele (CC), and the rest (CA or AA). With D3 supplementation, subjects with CA or AA alleles had significantly less increase in 25(OH)D3 and total 25(OH)D when compared with those with the CC allele. However, no difference was found when the supplement was vitamin D2.ConclusionGenetic variation in DBP (rs4588 SNP) influences responsiveness to vitamin D3 but not vitamin D2.

Risk of calcium oxalate nephrolithiasis after calcium or combined calcium and calcitriol supplementation in postmenopausal women

Abstract: Although calcium supplementation can cause hypercalciuria, the risk of nephrolithiasis has been shown to decrease rather than increase among subjects who had a higher calcium intake. Hypercalciuria is also a well-established side effect of calcitriol administration. However, the risk of nephrolithiasis is not well defined. The present study was undertaken to prospectively determine the effect of calcium with or without calcitriol on physicochemical risk factors associated with calcium oxalate nephrolithiasis in Thai postmenopausal women with osteoporosis. Subjects consisted of 53 Thai women more than 10 years postmenopausal who were randomly allocated to receive 750 mg of calcium carbonate supplement alone (n= 28) or 750 mg of calcium carbonate plus 0.5 mg calcitriol (n= 25) daily. Mean ± SEM for age was 65.3 ± 1.1 years, body weight 53.5 ± 1.3 kg. Urine samples for biochemical assays were collected at baseline and 3 months after treatment. Supersaturation for calcium oxalate stone formation was assessed from the 24 h urine constituents by the Tiselius’s index, AP(CaOx). Three months of calcium supplement alone resulted in a modest, but not significant, increase in urinary calcium (baseline, 2.90 ± 0.43 mmol/day; after treatment 3.58 ± 0.54 mmol/day) with no change in urinary oxalate, citrate or magnesium. In contrast, calcium together with calcitriol caused a significant increase in urinary calcium (baseline, 2.87 ± 0.41 mmol/day; after treatment, 4.08 ± 0.57 mmol/day; p<0.05). No significant change in other urine constituents after treatment with calcium and calcitriol was detected. Therefore, AP(CaOx) did not significantly increase either after calcium alone (baseline, 1.17 ± 0.39; after treatment, 1.36 ± 0.28) or after calcium plus calcitriol (baseline, 1.09 ± 0.17; after treatment, 1.09 ± 0.19). However, after treatments, 12 subjects (23%) – 6 receiving calcium supplement alone and 6 receiving calcium plus calcitriol supplement – had high AP(CaOx) values (greater than the upper limit of 95% CI for AP(CaOx) derived from non-stone-forming Thai women). The post-treatment/baseline ratio was 3.21 ± 0.74 for urinary calcium, 1.01 ± 0.19 for urinary oxalate, and 2.23 ± 0.42 (median 1.15) for AP(CaOx). The post-treatment/baseline ratio of calcium, but not for urinary oxalate, had a significant correlation with the post-treatment/baseline ratio of AP(CaOx). Our findings suggest that the alteration in the risk of calcium oxalate nephrolithiasis based on urinary composition is related to the alteration in urinary calcium. The risk of calcium oxalate nephrolithiasis does not increase significantly after calcium or combined calcium and calcitriol supplement in the majority of postmenopausal women with osteoporosis.

Vitamin D receptor gene polymorphism is associated with urinary calcium excretion but not with bone mineral density in postmenopausal women

Polymorphism of vitamin D receptor (VDR) gene has been found to be associated with serum osteocalcin (OC) levels and bone mineral density (BMD) in Caucasian identical twins and unrelated postmenopausal women. Being ethnically different and living in a geographic area with adequate vitamin D status due to abundant sunshine exposure, it is unclear whether VDR gene polymorphism will affect bone mass in Thai population. In the present study, we investigated the association between VDR gene polymorphism and bone metabolism in Thai postmenopausal women. Subjects consisted of 84 postmenopausal women. Bsm I, Taq I and Apa I polymorphisms of VDR gene were determined by PCR-RFLP. B, T and A represent the absence of the corresponding restriction sites while b, t and a indicate the presence of the restriction sites. Data were expressed as mean ± SE. Sixty-six subjects (78.6%) had bb genotype while 18 (21.4%) had Bb genotype. None of the subjects was found to have BB genotype. Taq I restriction site was in linkage disequilibrium to the Bsm I site. For Apa I polymorphism, 33 (39.3%), 42 (50.0%) and 9 (10.7%) of the subjects had aa, Aa and AA genotypes, respectively. There was no significant difference in serum intact OC levels and BMD at various skeletal sites among subjects with different genotypes. Despite the lack of difference in BMD and intact OC levels, subjects with bb genotype had higher 24-hour urinary calcium excretion than those with Bb genotype (bb, 6.1 ±0.3 mmol/day; Bb, 4.4±0.6 mmol/day; p<0.05). The effect of Bsm I VDR genotype was still significant (p<0.05) after dietary calcium intake was controlled using analysis of covariance. Despite the difference in urinary calcium levels, there was no significant difference in fractional excretion of calcium among subjects with different Bsm I-related genotypes, suggesting that the effect of the VDR gene polymorphism on urinary calcium excretion is more likely due to the effect on intestinal calcium absorption rather than renal tubular calcium reabsorption. We conclude that VDR genotype distributions in Thai postmenopausal women are different from those reported in Caucasians. VDR gene polymorphism does not appear to be associated with BMD or bone turnover in Thai postmenopausal women. However, Bsm I VDR polymorphism may have physiologic role in calcium homeostatasis by modulating intestinal calcium absorption.