Bone status measured by quantitative ultrasound: a comparison with DXA in Thai children

BACKGROUND/OBJECTIVES

Quantitative ultrasound (QUS) is used to measure bone quality and is known to be safe, radiation free and relatively inexpensive compared with dual-energy X-ray absorptiometry (DXA) that is considered the gold standard for bone status assessments. However, there is no consensus regarding the validity of QUS for measuring bone status. The aim of this study was to compare QUS and DXA in assessing bone status in Thai children.

SUBJECTS/METHODS

A total of 181 Thai children (90 boys and 91 girls) aged 6 to 12 years were recruited. Bone status was measured by two different techniques in terms of the speed of sound (SOS) using QUS and bone mineral density (BMD) using DXA. Calcium intake was assessed by 24 h diet recall. Pearson's correlation, κ-statistic and Bland and Altman analysis were used to assess the agreement between the methods.

RESULTS

There was no correlation between the two different techniques. Mean difference (s.d.) of the Z-scores of BMD and SOS was -0.61 (1.27) that was different from zero (P<0.05). Tertiles of Z-scores of BMD and QUS showed low agreement (κ 0.022, P=0.677) and the limits of agreement in Bland and Altman statistics were wide.

CONCLUSIONS

Although QUS is easy and convenient to use, the SOS measurements at the radius seem not appropriate for assessing bone quality status.

Prevalence of overweight and obesity in Thai population: results of the National Thai Food Consumption Survey

Overweight and obesity are considered a serious health problem in Thailand. This study examined the prevalence of overweight and obesity in a nationally representative sample of Thai children and adults based on international standards. A cross-sectional population survey of 16,596 Thais aged 3 years and over was conducted. Heights and weights were obtained using standardized methods. Estimates of the overweight and obesity prevalence in children, adolescents, and adults were computed. The prevalence of overweight and obesity among children and adolescents aged 3 to 18 years was 7.6% and 9.0%, respectively, and was higher among boys than girls. Among adults, using the the Regional Office for the Western Pacific (WPRO) standard, 17.1% of adults were classified as overweight [body mass index (BMI) 23.0-24.9 kg/m²], 19.0% as class I obesity (BMI 25.0-29.9 kg/m²), and 4.8% as class II obesity (BMI ≥ 30.0 kg/m²). Using the World Health Organization (WHO) definition, 19.0% were overweight (BMI 25-29.9 kg/m²), 4.0% class I obesity (BMI 30.0-34.9 kg/m²), 0.8% class II obesity (BMI 35.0-39.9 kg/m²), and 0.1% class III obesity (BMI ≥ 40.0 kg/m²). There was a vast difference in obesity prevalence between the WHO and the WPRO criteria. Obesity prevalence when using the WPRO definition (23.8%) was almost five times greater than when defined with the WHO standard (4.9%). The present study found a high prevalence of overweight and obesity in nationally representative sample of the Thai population. Higher rates of overweight and obesity prevalence were computed using the WPRO standard when compared to the WHO standard.

Effects of physical activity and dietary calcium intake on bone mineral density and osteoporosis risk in a rural Thai population

The objective of the study was to determine the effects of modifiable risk factors on bone mineral density in postmenopausal Thai women. Dietary calcium intake (g/day), energy expenditure (kcal/day), and sunlight exposure (h/day) were assessed in 129 rural Thai women aged 63 years (range 50 to 84 years). Bone mineral density (BMD) at the femoral neck, lumbar spine, and distal radius were measured by dual-energy X-ray absorptiometry (DXA). The average dietary calcium intake was 236 +/- 188 g/day (mean +/- SD), while the energy expenditure was 2,118 +/- 656 kcal/day with 1.1 +/- 1.7 h of sunlight exposure. In multiple linear regression analysis, dietary calcium intake, energy expenditure, and years since menopause were significant and independent predictors of BMD at various sites. The three factors together accounted for between 35% and 45% of the variance of BMD. The prevalence of osteoporosis (defined as BMD T-scores < or =-2.5) was 33% at the femoral neck, 42% at the lumbar spine, and 35% at the distal radius. The risk of osteoporosis was higher in women with lower dietary calcium intake (< or =138 mg/day; prevalence rate ratio [PRR], 1.4; 95% confidence interval [CI], 1.0 to 1.9), lower energy expenditure (< or =1,682 kcal; PRR, 1.7; 95% CI, 1.2 to 2.3), and greater years since menopause (> or =6 years; PRR, 2.6; 95% CI, 1.2 to 5.8). The population attributable risk fraction of osteoporosis risk due to the three factors was 70%. These results suggest that in the Thai population, low dietary calcium intake and low physical activity together with advancing years since menopause were independent risk factors for low BMD.

Different mechanism of bone loss in ageing women and men in Khon Kaen Province

The changes of vitamin D status and biochemical markers of bone turnover have been reported with aging. In this study we determined age-related levels of vitamin D and biochemical markers of bone turnover in the general adult population between the ages of 20 and 84 years who were living in Khon Kaen province in northeastern Thailand. Serum 25 hydroxyvitamin D was determined as an indicator of vitamin D status. Serum total alkaline phosphatase and N-terminal mid fragment osteocalcin were measured as biochemical markers of bone formation and serum C-terminal fragment of type I collagen was measured as a marker of bone resorption. The levels of serum 25 hydroxyvitamin D were high in the Khon Kaen population. Men had higher levels of 25 hydroxyvitamin D than did women. However, there were no changes with age in either sex. In women, all biochemical markers of bone turnover increased with age after the fourth decade. The sharp increase was observed in the sixth decade which was around the menopausal age. In contrast, in men all biochemical markers of bone turnover except serum total alkaline phosphatase had a tendency to decrease with age.

CONCLUSION

There was no evidence of vitamin D deficiency in a Khon Kaen population. In addition, serum vitamin D levels did not decline with ageing. Women and men showed different changes of biochemical markers of bone turnover with ageing indicating gender difference in the pathogenesis of osteoporosis.

Elevated serum cholesterol levels in Bangkok children and adolescents

Hypercholesterolemia is a major cardiovascular risk factor. This study aimed to assess serum total cholesterol (TC) levels of children and adolescents living in Bangkok, Thailand. During 1995-1997, nonfasting blood samples were obtained from 570 healthy school children and adolescents aged 9-18 years. The mean TC levels ranged from 143-180 mg/dl in males and from 145-202 mg/dl in females. The prevalences of hypercholesterolemia (TC > or = 200 mg/dl) were 12.2 per cent and 20.3 per cent in males and females, respectively. Twenty-eight per cent of males and 26.9 per cent of females had borderline values (TC 170-199 mg/dl). TC inversely correlated with age (r = -0.16, P < 0.01) in males. The findings indicate that notable percentage of these children had elevated cholesterol levels and warrant additional study concerning risk factors and tracking of lipoprotein levels from childhood into adulthood.

Lymphocyte responsiveness of children supplemented with vitamin A and zinc

We sought to determine the effect of supplementation with zinc, vitamin A, or a combination of the two on proliferation of T lymphocytes to concanavalin A (ConA), tetanus toxoid (TT), or tuberculin (PPD) of children living in a region endemic for suboptimal vitamin A and zinc intake. The children (n = 140, aged 6-13 y) were randomly assigned and supplemented with either zinc (25 mg/d), vitamin A (1500 mg RE/d), zinc + vitamin A, or placebo for 6 mo. After a baseline blood collection, subjects were boosted with diphtheria-tetanus antigen. Proliferative responsiveness of T lymphocytes to ConA and TT in each treatment group (n = 35) was not different at baseline or postsupplementation. Children supplemented with zinc + vitamin A tended to show higher proliferative responsiveness of T lymphocytes to PPD than did those treated with placebo (P = 0.08). This tendency was observed in females but not in males. Increased zinc and vitamin A intake could result in health benefits for children living in regions endemic for suboptimal micronutrient nutriture.

Effects of an iron supplementation trial on the Fe status of Thai schoolchildren

A double-blind clinical trial was conducted among 9- to 11-year-old children in sixteen schools in the Chon Buri province of Thailand to assess the effects of an iron supplement combined with an anthelminthic agent (i.e. albendazole). In addition to the albendazole, Fe or placebo tablets were distributed to 2268 children enrolled in grades three to five without knowledge of the Fe status of the children. Criteria for case inclusion were: (a) absence of A E Bart's or haemoglobin (Hb) H disease, (b) absence of abnormal Hb EE, and (c) age, 108-144 months. The results showed a significant improvement in the Fe status of the children after 16 weeks of treatment. The increments were: Hb from 124 to 128 g/l, serum ferritin from 34.54 to 104.72 micrograms/l, transferrin saturation from 24.09 to 35.05%; free erythrocyte protoporphyrin decreased from 444.7 to 281.4 micrograms/l erythrocytes. These changes were significantly greater than in the control group that received only the anthelminthic agent. However, the administration of albendazole only also resulted in significant changes in the same Fe indicators.

Effect of vitamin A and zinc supplementation on the nutriture of children in Northeast Thailand

Previous surveys suggested that young children in Northeast Thailand may benefit from vitamin A and/or zinc supplementation. One hundred thirty-three children aged 6-13 y with marginal plasma retinol (less than 1.05 mumol/L) and Zn (less than 12.2 mumol/L) concentrations participated in a double-blind study. They were randomly assigned and supplemented with either zinc (25 mg/d), vitamin A (1500 RE/d), zinc plus vitamin A, or placebo for 6 mo. Biochemical indices of vitamin A (plasma vitamin A, retinol-binding protein) and zinc status (plasma zinc, alkaline phosphatase) increased significantly. The children had adequate liver stores of vitamin A (relative dose response less than 20%). Zinc supplementation resulted in an improvement in vision restoration time (VRT) in dim light (dark adaptometry). Vitamin A and zinc synergistically normalized conjunctival epithelium as measured by conjunctival impression cytology (CIC). Both functional indices, VRT and CIC, showed significant correlations with plasma zinc and vitamin A, respectively. The data suggest that functional improvements in populations with suboptimal vitamin A and zinc nutriture can be accomplished by supplementation with less than two times the recommended dietary allowance of these nutrients.

Biochemical evidence suggestive of suboptimal zinc and vitamin A status in schoolchildren in northeast Thailand

Data are accumulating that support the hypothesis that inadequate zinc nutriture will result in an impairment of vitamin A utilization. Therefore, zinc and vitamin A status were assessed in 283 schoolchildren aged 7-13 y in Northeast Thailand. More than one-fourth had serum vitamin A concentrations less than 0.86 mumol/L , with a mean (+/- SD) concentration of 1.06 +/- 0.31 mumol/L compared with 1.26 +/- 0.02 mumol/L for US children of similar age. Seventy percent had low serum zinc concentrations, less than 10.7 mumol/L. Twenty-three percent of the children exhibited both low serum zinc and vitamin A concentrations. The mean concentration of retinol-binding protein (RBP) was lower for children in this study compared with healthy Thai children in Bangkok, 22.5 +/- 6.6 vs 25.3 +/- 6.0 mg/L, respectively. Serum zinc and RBP were significantly correlated (p less than 0.001) whereas vitamin A and zinc were not correlated. These data suggest that a high proportion of rural schoolchildren in Northeast Thailand are at risk of inadequate zinc and/or vitamin A nutriture.