Bone Mineral Mass Research Articles

S1051 Faecal Calprotectin Home Test in Ulcerative Colitis - Is It Possible?

S1051 Faecal Calprotectin Home Test in Ulcerative Colitis - Is It Possible?

Hormones, Nutrients and Postmenopausal Bone Loss.

The loss of bone mineral mass in postmenopausal women was retarded by a cyclical synthetic gonadal hormone preparation. A thiazide diuretic and four nutrient supplements tested did not affect the rate of bone loss after menopause.

Validation of DXA Body Composition Estimates in Obese Men and Women

The aim of this study was to determine the accuracy of dual-energy X-ray absorptiometry (DXA)-derived percentage fat estimates in obese adults by using four-compartment (4C) values as criterion measures. Differences between methods were also investigated in relation to the influence of fat-free mass (FFM) hydration and various anthropometric measurements. Six women and eight men (age 22-54 years, BMI 28.7-39.9 kg/m(2), 4C percent body fat (%BF) 31.3-52.6%) had relative body fat (%BF) determined via DXA and a 4C method that incorporated measures of body density (BD), total body water (TBW), and bone mineral mass (BMM) via underwater weighing, deuterium dilution, and DXA, respectively. Anthropometric measurements were also undertaken: height, waist and gluteal girth, and anterior-posterior (A-P) chest depth. Values for both methods were significantly correlated (r(2) = 0.894) and no significant difference (P = 0.57) was detected between the means (DXA = 41.1%BF, 4C = 41.5%BF). The slope and intercept for the regression line were not significantly different (P > 0.05) from 1 and 0, respectively. Although both methods were significantly correlated, intraindividual differences between the methods were sizable (4C-DXA, range = -3.04 to 4.01%BF) and significantly correlated with tissue thickness (chest depth) or most surrogates of tissue thickness (body mass, BMI, waist girth) but not FFM hydration and gluteal girth. DXA provided cross-sectional %BF data for obese adults without bias. However, individual data are associated with large prediction errors (+/-4.2%BF). This error appears to be associated with tissue thickness indicating that the DXA device used may not be able to accurately account for beam hardening in obese cohorts.

Body Composition of Female Wheelchair Athletes

Wheelchair users undergo changes in body composition as a result of disability. In this study the distribution of bone mineral, lean and fat mass was assessed in highly-trained female wheelchair athletes and a reference group by dual-energy X-ray absorptiometry (DXA). The transferability of anthropometric equations commonly used in female groups was examined in order to establish a suitable field method of body composition assessment. The DXA total-body results indicated no difference between groups, but segmental analyses uncovered regional differences. The wheelchair athletes had greater BMD (p=0.088), more lean mass (p<0.001) and a lower percent fat (p=0.050) in their arms. The reverse was true of the legs (p< or =0.001). The trunk as a whole did not differ between groups. In general, the anthropometric equations showed a lack of transferability to the wheelchair group and tended to underestimate total percent body fat. Anthropometric measures such as body mass index (BMI) and waist girth showed strong correlations with body fat in the wheelchair group (BMI: r=0.90, p=0.001; waist: r=0.83, p=0.001), but weaker results in the reference group. It is recommended that specific anthropometric equations be developed for use in the absence of a 'gold standard' measure of body composition such as DXA.

Body size, body composition and fat distribution: comparative analysis of European, Maori, Pacific Island and Asian Indian adults

Although there is evidence that Asian Indians, Polynesians and Europeans differ in their body fat (BF)-BMI relationships, detailed comparative analysis of their underlying body composition and build characteristics is lacking. We investigated differences in the relationships between body fatness and BMI, fat distribution, muscularity, bone mineral mass, leg length and age-related changes in body composition between these ethnic groups. Cross-sectional analysis of 933 European, Maori, Pacific Island and Asian Indian adult volunteers was performed for total and percentage of BF, abdominal fat, thigh fat, appendicular muscle mass, bone mineral content and leg length measured by dual-energy X-ray absorptiometry. Asian Indian men and women (BMI of 24 and 26 kg/m2, respectively) had the same percentage of BF as Europeans with a BMI of 30 kg/m2 or Pacific men and women with BMI of 34 and 35 kg/m2, respectively. Asian Indians had more fat, both total and in the abdominal region, with less lean mass, skeletal muscle and bone mineral than all other ethnic groups. Leg length was relatively longer in Pacific men and Asian and Pacific women than in other ethnic groups. In Asian Indians, abdominal fat increased with increasing age, while the percentage of BF showed little change. In the other ethnic groups, both abdominal and total BF increased with age. In conclusion, ethnic differences in fat distribution, muscularity, bone mass and leg length may contribute to ethnic-specific relationships between body fatness and BMI. The use of universal BMI cut-off points may not be appropriate for the comparison of obesity prevalence between ethnic groups.

Deleterious Effect of Late Menarche on Distal Tibia Microstructure in Healthy 20-Year-Old and Premenopausal Middle-Aged Women

Late menarche is a risk factor for fragility fractures. We hypothesized that pubertal timing-dependent alterations in bone structural components would persist from peak bone mass to menopause, independent of premenopausal bone loss. We studied the influence of menarcheal age (MENA) on femoral neck BMD (FN aBMD) by DXA and microstructure of distal tibia by HR-pQCT in healthy young adult (YAD; 20.4 +/- 0.6 [SD] yr, n = 124) and premenopausal middle-aged (PREMENO; 45.8 +/- 3.4 yr, n = 120) women. Median of MENA was 13.0 +/- 1.2 and 13.1 +/- 1.7 yr in YAD and PREMENO, respectively. In YAD and PREMENO (n = 244), FN aBMD (R = -0.29, p = 0.013), as well as total volumetric BMD (Dtot; R = -0.23, p = 0.006) and cortical thickness (Ct.Th; R = -0.18, p = 0.011) of distal tibia were inversely correlated to MENA. After segregation by the median of MENA in EARLY and LATE subgroups, the significant influences of both MENA (p = 0.004) and chronological age (p < 0.0001) were observed for FN aBMD and trabecular bone volume fraction of the distal tibia with similar differences in T-scores between LATE and EARLY subgroups in YAD (-0.36 and -0.31 T-scores) and PREMENO (-0.35 and -0.42 T-scores) women. Ct.Th was negatively influenced by MENA, whereas trabecular thickness (Tb.Th) was negatively influenced by chronological age. There was a striking inverse relationship between cross-sectional area and Ct.Th (R = -0.57, p < 0.001). In conclusion, the negative influence of late menarcheal age at weight-bearing sites as observed by the end of skeletal growth remains unattenuated a few years before menopause and is independent of premenopausal bone loss. Alterations in both bone mineral mass and microstructural components may explain the increased risk of fragility fractures associated with later menarcheal age.

The importance and relevance of peak bone mass in the prevalence of osteoporosis

Bone mass and strength achieved at the end of the growth period, simply designated as 'Peak Bone Mass (PBM)', plays an essential role in the risk of osteoporotic fractures occurring in adulthood. It is considered that an increase of PBM by one standard deviation would reduce the fracture risk by 50%. As estimated from twin studies, genetics is the major determinant of PBM, accounting for about 60 to 80% of its variance. During pubertal maturation, the size of the bone increases whereas the volumetric bone mineral density remains constant in both genders. At the end of puberty, the sex difference is essentially due to a greater bone size in male than female subjects. This is achieved by larger periosteal deposition in boys, thus conferring at PBM a better resistance to mechanical forces in men than in women. Sex hormones and the IGF-1 system are implicated in the bone sexual dimorphism occurring during pubertal maturation. The genetically determined trajectory of bone mass development can be modulated to a certain extent by modifiable environmental factors, particularly physical activity, calcium and protein intakes. Prepuberty appears to be an opportune time to modify environmental factors that impinge on bone mineral mass acquisition.

Adipocytokine and ghrelin levels in relation to bone mineral density in physically active older women: longitudinal associations

We investigated the relationship between the decrease in bone mineral mass (BMC) and bone mineral density (BMD) values with baseline adipocytokine and ghrelin concentrations in physically active postmenopausal women. Leptin, adiponectin, ghrelin, BMC, BMD and different body composition values were measured in 35 women (age: 69.7+/-6.0 years) before and after a 12-month prospective study period. Significant (P<0.05) decreases in fat-free mass (FFM) (by 2.56%) and BMC (by 1.63%) and increases in adiponectin (by 14.8%) were seen in older females as a result of the study period. The independent variables that were associated with decreases in total BMC were baseline fat mass (FM) and adiponectin explaining 30.6% (R(2)x100) of the total variance. In another model, baseline FFM and leptin were the independent variables that explained 20.6% (P<0.05) of the total variance in the decreases in total BMD value. The variables that were associated with decreases in femoral neck BMD were FM and leptin (R(2)=0.102; P<0.05), while the independent variables were baseline trunk fat:leg fat ratio and adiponectin in the model with decreases in lumbar spine BMD as the dependent variable, and accounted for 13.1% (P<0.05) of the decreases in BMD variance. Initial adiponectin concentration together with specific body composition characteristics predicted loss in BMC and lumbar spine BMD values, while initial leptin concentration together with specific body composition parameters determined the loss in total and femoral neck BMD values in physically active older women.

The influence of ghrelin, adiponectin, and leptin on bone mineral density in healthy postmenopausal women

The association of body fat mass (FM) with bone mineral mass (BMC) and bone mineral density (BMD) has been attributed to a mechanical load exerted on the skeleton by FM and by the effect of different hormones. The aim of the present study was to determine whether there is a relationship between ghrelin, adiponectin, and leptin with BMC and BMD in healthy postmenopausal women (n = 88; age, 68.9 +/- 6.8 years; body mass index, 27.4 +/- 3.6 kg/m(2)). Body composition, BMC, and BMD were derived by dual-energy X-ray absorptiometry. Waist-to-hip (WHR) and waist-to-thigh (WTR) ratios were also obtained. Ghrelin was associated with total BMC (beta = -0.945; P = 0.0001), total BMD (beta = -0.959; P = 0.0001), lumbar spine BMD (beta = -0.945; P = 0.0001), and femoral neck BMD (beta = -0.957; P = 0.0001), and remained associated (P < 0.041) in different analyses that controlled for measured body composition and hormonal and insulin resistance values. However, the associations between ghrelin and measured bone mineral values were no longer significant (P > 0.149) when adjusted for body fat distribution values (WHR, WTR). Adiponectin was significantly related to total BMC (beta = -0.931; P = 0.0001), total BMD (beta = -0.940; P = 0.0001), lumbar spine BMD (beta = -0.937; P = 0.0001), and femoral neck BMD (beta = -0.940; P = 0.0001) values, and these relationships remained significant (P < 0.019) after adjusting for measured body fat, hormonal, and insulin resistance values but not when adjusted for fat-free mass (FFM; P > 0.106). In addition, significant associations of leptin with total BMC (beta = 0.912; P = 0.0001), total BMD (beta = 0.907; P = 0.0001), lumbar spine BMD (beta = 0.899; P = 0.0001), and femoral neck BMD (beta = 0.906; P = 0.0001) were found. These associations remained significant (P < 0.010) in different analyses that controlled for hormonal and insulin resistance values, but the associations between leptin and bone mineral values were no longer significant (P > 0.145) when adjusted for specific body composition values (WHR, WTR, FM, and FFM). In conclusion, it appears that the influence of plasma ghrelin, adiponectin, and leptin levels on BMC and BMD values is mediated or confounded by the specific body composition parameters in healthy postmenopausal women.

Prevalence of Low Bone Mass and Deficiencies of Vitamins D and K in Pediatric Patients With Cystic Fibrosis From 3 Canadian Centers

In this cross-sectional observational study, we assessed both vitamins D and K status and bone health in pancreatic insufficient pediatric patients with cystic fibrosis from 3 Canadian cystic fibrosis centers. Eighty-one patients who had cystic fibrosis and were clinically stable for at least 3 months were enrolled. At the time of the clinic visit, anthropometric variables, lung function, pubertal status, intake of calcium and vitamins D and K, and physical activity were assessed. Blood was taken for analysis of biochemical biomarkers of bone turnover and status of vitamins D and K, and a urine sample was obtained for calcium, creatinine, sodium, and deoxypyridoline analyses. Whole-body bone mineral content and lumbar spine (L1-L4) bone mineral density were measured. The children were relatively well nourished and had moderate to mild lung disease. Low bone mineral mass defined as a z score between -1.0 and -2.0, for gender and age was detected in 38% of the children for whole body and in 28% for lumbar spine. z score less than -2.0 was observed in 7 children for both bone measures. Suboptimal vitamin D status occurred in 95% of patients; suboptimal vitamin K status occurred in 82% of patients. Measures of plasma osteocalcin and carboxy-terminal propeptide type 1 procollagen and urinary deoxypyridoline compared with reference values for age, gender, and pubertal status reflected a state of suppressed bone formation and elevated bone resorption in a large proportion of the patients. Bone mass of the whole body and spine was lower than expected for chronological age in approximately one third of pediatric patients with cystic fibrosis irrespective of gender or age. This may be explained by the observation of low bone turnover for developmental stage as indicated by bone biomarkers. Suboptimal status of vitamins D and K may be key causative factors of the low bone status for age.

Low bone mineral status in adolescent idiopathic scoliosis.

Adolescent idiopathic scoliosis (AIS) is a pathological entity of unknown etiology. The causes of osteoporosis or osteopenia in AIS remain undetermined. Whether poor bone quality is an etiologic factor remains controversial. To determine the correlation between low bone mineral status and AIS, a review of literature was performed. After a literature search from 1966 to June 2007 (using Medline, EMBASE, Cochrane DSR, ACP Journal Club, DARE, CCTR, CINAHL and hand searches of references) for studies regarding low bone mineral status and AIS, 20 studies meeting the inclusion criteria were reviewed in terms of the appropriateness of valuation technique, the validity of descriptive system, the number and type of respondents, and overall quality of the studies. Nearly all investigations demonstrated that low bone mineral density (BMD) was a generalized phenomenon and a systematic disorder in AIS. The prevalence of AIS with osteoporosis is approximately 20-38%. The follow-up studies indicated that osteopenia in patients with AIS may be a persistent phenomenon. BMD could be affected by the mechanical loading and lower bone mineral mass is always associated with lower bone strength. The spinal architecture associated with the osteopenia may aggravate the spinal deformity. However, with regard to the concave and convex femoral neck BMD values, and the correlation of BMD to scoliosis parameters, the results remain inconsistent. Bracing may not result in permanent loss of bone mineral mass. The effect of the eccentric tension-compression environments on BMD, the correlation of BMD with scoliosis parameters and the effect of bracing on BMD should be investigated further in prospective, randomized and longitudinal follow-up studies.

Percent true calcium absorption, mineral metabolism, and bone mineralization in children with cystic fibrosis: Effect of supplementation with vitamin D and calcium

To assess whether percent true calcium absorption (alpha) is normal in children with cystic fibrosis (CF) and to assess whether supplementation with 2,000 IU vitamin D(3), 1 g calcium, or both will alter alpha, mineral metabolism, and/or bone mass in children with CF. Fifteen children ages 7-13 were randomly assigned to one of four different orders to receive all four 6-month treatments including placebos. Change in 25-hydroxyvitamin D (25-OHD), 1,25-dihydroxyvitamin D (1,25(OH)(2)D), PTH, bone turnover markers, and minerals after 6 months, and bone mineral content (Hologic 1000W) after 9 months was measured. alpha was measured by a dual stable isotope method using (48)Ca intravenously and (46)Ca orally and measuring (48)Ca, (46)Ca, and (42)Ca in a 24-hr urine using High Resolution Inductively Coupled Mass Spectroscopy (HR-ICP-MS). Analysis used Wilcoxon Sign Ranks. alpha was in the normal range and did not differ by treatment (P 35 +/- 10%, Ca 38 +/- 23%, D 36 +/- 11%, D + Ca 46 +/- 21%). One gram calcium did not increase serum or urine calcium. Two thousand IU D(3) did not increase 25-OHD or change 1,25(OH)(2)D. Serum and urine minerals, markers of bone turnover and bone mineral gains did not differ by treatment. alpha is normal in children with CF. One gram calcium and/or 2,000 IU D(3) does not change alpha or increase 25-OHD, serum calcium, or mineralization. Longer trials of a significantly higher dose of vitamin D(3) shown to increase serum 25-OHD are needed to assess effects on mineral metabolism and bone mass accrual. However, study of therapeutic options other than calcium and vitamin D should be encouraged.

The vitamin D receptor Fok1 polymorphism and bone mineral density in Chinese children

Background To evaluate the relationship between vitamin D receptor (VDR) gene polymorphism and bone mineral density (BMD) in 213 healthy children aged 6–10 year in China. Methods A questionnaire survey of dietary pattern, outdoor activity was conducted among 213 children (boys 126, girls 86) randomly selected in Xishui county of Hubei province. The BMD was determined by dual energy X-ray absorptiometry at the distal forearm, calcium, phosphorus, and alkaline phosphatase in serum were immediately analyzed. The FokI polymorphism was detected by using PCR-RFLP. Results BMD was significantly higher in boys than in girls in 8/9 year group. (2) the frequencies of FF, Ff, and ff genotype were 25.8%, 62.0% and 12.2%, respectively; no difference was found between boys and girls. (3) BMD of children carrying FF genotype was higher (0.256 ± 0.03) than those of carrying Ff genotype (0.241 ± 0.03), P < 0.01; the Ff genotype was associated with lowest forearm BMD in both boys and girls. Outdoor activity also positively affected peak bone mass. Conclusion The Fok1 polymorphism of the VDR receptor seems to directly affect bone mineral mass in Chinese children.

Body composition: validity of segmental bioelectrical impedance analysis.

Bioelectrical impedance analysis (BIA) measures the impedance associated with passage of an alternating current through the body which is proportional to total body water (TBW) and therefore can provide expedient estimates of body composition. However, little validity information is available for commercially available bathroom scale type devices which perform whole body estimates from segmental (lower limb) measurements. This study therefore compared body composition estimates between a commercially available segmental BIA device (Tanita BC-532) and four compartment criterion values. Body composition of nine males and nine females (mean +/- SD: 37.7 +/- 18.7 yr; 170.7 +/- 5.3 cm; 68.38 +/- 9.7 kg) was determined via BIA and a four compartment model incorporating measures of body density, TBW and bone mineral mass. While the mean %BF and fat free mass (FFM) values for both methods were not significantly different, considerable intra-individual differences were observed. BIA values varied from the four compartment values by -3.0 to 4.4 %BF and -3.3 to 1.9 kg FFM. The BIA estimates of TBW were significantly different from the criterion measures and intraindividual differences displayed a large range (-0.6 to 3.6 kg). Significant underestimations of TBW via BIA are concerning given that this is the parameter initially established by this method. Furthermore, the BIA data resulted in a FFM hydration value of 68.5% which was significantly (p<0.001) lower than the four compartment value of 72.0%. In conclusion, the BIA device tested displayed poor individual accuracy for the estimation of body composition compared with a four compartment criterion method.

High-Protein Intake Enhances the Positive Impact of Physical Activity on BMC in Prepubertal Boys

In 232 healthy prepubertal boys, increased physical activity was associated with greater BMC at both axial and appendicular sites under high-protein intake. Physical activity is an important lifestyle determinant of bone mineral mass acquisition. Its impact during childhood can be modulated by nutrition, particularly by protein and calcium intakes. We analyzed the relationship between physical activity levels and protein compared with calcium intake on BMC. In 232 healthy prepubertal boys (age: 7.4 +/- 0.4 [SD] yr; standing height: 125.7 +/- 5.9 cm; body weight: 25.3 +/- 4.6 kg), physical activity and protein and calcium intakes were recorded. BMC was measured by DXA at the radial metaphysis, radial diaphysis, total radius, femoral neck, total hip, femoral diaphysis, and L(2)-L(4) vertebrae. In univariate analysis, the correlation coefficients r with BMC of the various skeletal sites were as follows: physical activity, from 0.26 (p = 0.0001) to 0.40 (p = 0.0001); protein intake, from 0.18 (p = 0.005) to 0.27 (p = 0.0001); calcium intake, from 0.09 (p = 0.181) to 0.17 (p = 0.007). By multiple regression analysis, the beta-adjusted values remained correlated with BMC, ranging as follows: physical activity, from 0.219 (p = 0.0007) to 0.340 (p < 0.0001); protein intake, from 0.120 (p = 0.146) to 0.217 (p = 0.009). In contrast, it was not correlated for calcium intake: from -0.069 (p = 0.410) to 0.001 (p = 0.986). With protein intake (mean = 2.0 g/kg body weight/d) above the median, increased physical activity from 168 to 321 kcal/d was associated with greater mean BMC Z-score (+0.6, p = 0.0005). In contrast with protein intake (mean = 1.5 g/kg body weight/d) below the median, increased physical activity from 167 to 312 kcal/d was not associated with a significantly greater mean BMC Z-score (+0.2, p = 0.371). The interaction between physical activity and protein intake was close to statistical significance for mean BMC Z-score (p = 0.055) and significant for femoral neck BMC (p = 0.012). In keeping with the results derived from multiple regression analysis, the increased physical activity on mean BMC Z-score was not influenced by difference in calcium intake above (mean = 945 mg/d) and below (mean = 555 mg/d) the median. In healthy prepubertal boys, the impact in increased physical activity on BMC seems to be enhanced by protein intake within limits above the usual recommended allowance.

The Effects of Dietary Protein on Bone Mineral Mass in Young Adults May Be Modulated by Adolescent Calcium Intake ,

The effect of dietary protein on bone mass measures at different life stages is controversial. We investigated the influence of protein intake on bone mass measures in young adults, considering the influence of calcium intake through adolescence. Subjects were 133 young adults (59 males, 74 females) who were participating in the Saskatchewan Pediatric Bone Mineral Accrual Study (1991–1997, 2003–2006). At adulthood, their mean age was 23 y. We assessed dietary intake via serial 24-h recalls carried out at least once yearly. Total body (TB) bone mineral content (BMC) and TB bone mineral density (BMD) were assessed annually using Dual energy X-ray absorptiometry. We determined TB-BMC net gain from the age of peak height velocity (PHV) to early adulthood. We analyzed data from all subjects and subsets based on sex and calcium intake using multiple regression. TB-BMC significantly increased from age at PHV to early adulthood by 41% in males and 37% in females. Height, weight, physical activity, and sex were significant predictors of TB-BMC, TB-BMC net gain, and TB-BMD among all subjects. Protein intake predicted TB-BMC net gain in all subjects (β = 0.11; P = 0.015). In females at peri-adolescence or early adulthood with adequate calcium intake (>1000 mg/d), protein intake positively predicted TB-BMC, TB-BMC net gain, and TB-BMD (P < 0.05). Our results indicate that when calcium intake is adequate, protein intake has a beneficial effect on the bone mass of young adult females. Protein, in the absence of sufficient calcium, does not confer as much benefit to bone.

Dependence of ultrasonic attenuation on bone mass and microstructure in bovine cortical bone

The development of the axial transmission technique now enables in vivo evaluation of cortical bone quality, which plays an important role in bone fragility. Cortical bone is a complex multiscale material, which may be made of different types of microstructure. The interaction between ultrasound and cortical bone remains unclear and most studies have been confined to wave speed analysis. The first aim of this study is to investigate the dependence of the frequency-dependent attenuation on the type of bone microstructure. The second goal is to determine whether broadband ultrasonic attenuation (BUA) is related to volumetric bone mineral density (vBMD) and mass density. Parallelepipedic samples of bovine cortical bone were cut from three specimens and tested in the axial, radial and tangential directions using an ultrasonic transmission device. BUA was evaluated over a 1-MHz wide bandwidth around 4 MHz. In addition, the microstructure of each sample was determined using an optical microscope. BUA values measured in porotic microstructure are significantly higher than in Haversian microstructure. The lowest BUA values are obtained for plexiform microstructure. For all structures, BUA in the axial direction is significantly smaller than in the radial and tangential directions. Moreover, BUA is correlated with both vBMD and density (determination coefficient ( R 2) equal to 0.44 and 0.65, respectively, in the axial direction). BUA variations can be explained by scattering and viscoelastic mechanisms. This study suggests that BUA measurements have the potential to discriminate among different cortical bone microstructures in addition to providing material properties.

An Inulin-Type Fructan Enhances CalciumAbsorption Primarily via an Effect on Colonic Absorption in Humans ,

Calcium absorption efficiency and bone mineral mass are increased in adolescents who regularly consume inulin-type fructans (ITF). The mechanism of action in increasing absorption is unknown but may be related to increased colonic calcium absorption. We conducted a study in young adults designed to evaluate these mechanisms with a kinetic technique using 42Ca orally and 46Ca dosed i.v. Those who responded to 8 wk of supplementation with 8 g of a mixed short and long degree of polymerization ITF by increasing their calcium absorption had kinetic measurements analyzed to evaluate the time course of absorption. The area under the curve of the oral tracer in the blood during the 26 h after dosing was calculated and the time dependence of increased absorption determined. Eight young adults (of 13 studied), with mean calcium intake ∼900 mg/d, responded to the ITF with an increased calcium absorption of at least 3%. In responders, absorption increased from 22.7 ± 11.3% to 31.0 ± 15.3%. Colonic absorption, defined as absorption that occurred >7 h after oral dosing, represented 69.6 ± 18.6% of the increase, or 49 ± 28 mg/d. These findings suggest that, in those who respond to ITF, its effects on calcium absorption occur principally in the colon. This benefit to ITF may be especially important when absorption in the small intestine is impaired for anatomic or physiological reasons.

Patient Quality of Life Safeguarding: The Primary Aim in Nonmetastatic Prostate Cancer Patients

TO THE EDITOR: It was with great interest that we read Michaelson et al’s article in the Journal of Clinical Oncology concerning the role of a single treatment with zolendronic acid to prevent gonadotropin-releasing hormone (GnRH) agonistinduced bone loss in men with nonmetastatic prostate cancer. In this well-set-out study, which showed that a single dose of zolendronic acid (4 mg once in 12 months) significantly increases bone mineral density (BMD) and durably suppresses biochemical markers of bone turnover, the authors highlighted a most important feature of nonmetastatic prostate cancer treatment (ie, the need for patient quality of life [QoL] safeguarding). Therefore, in patients affected by nonmetastatic prostate cancer, the preservation of patient QoL is an essential target because of the fact that this neoplasm often has nonaggressive biologic and clinical behavior. However, we would like to make an additional consideration regarding their study. The authors enrolled 44 patients (22 treated and 22 placebo), who had undergone GnRH agonist throughout the study with a different duration of prior GnRH agonist treatment of 21 17 months for the zoledronic acid group and 12 16 months for the placebo group. The authors, however, when explaining their study limitations, state that BMD decreases at a steady rate regardless of the duration of past GnRH agonist exposure, as reported by Lee et al. We would like to highlight the fact that a more rapid mineral bone mass reduction is associated with initial serum testosterone decreasing to castrate levels, due to a higher bone turnover, as reported by Greenspan et al. This aspect is crucial and well known in the bone mineral mass loss related to postmenopausal hormonal changes. Consequently, the question is since BMD reduction prophylaxis with a single dose of zolendronic acid is really useful in nonmetastatic prostate cancer patient QoL safeguarding, can it be useful to select the best time for administering this kind of treatment? On the basis of this well-presented study, we think that the fact should be stressed that early administration of zolendronic acid should be suggested in nonmetastatic prostate cancer patients treated with GnRH agonist, particularly to reduce the costs related to fracture due to GnRH agonist-induced osteoporosis.

Relationship between Serum Leptin and Bone Density in Young and Older Women

Leptin is involved in the regulation of body weight and energy homeostasis. Recently, it has been linked to bone metabolism with decreased leptin levels being associated with a loss of bone mass. PURPOSE: We examined the relationship between serum leptin levels and bone mineral density (BMD) in sedentary women, ages 18–75 years (n=81). METHODS: Healthy premenopausal (Y; 18–30 yrs; n=32) and postmenopausal (O; 60–75 yrs; n=49) women were recruited for this study. Total body, AP spine, and left proximal femur BMD sites were assessed by DXA (GE Lunar Prodigy, software version 8.80.001). Body composition variables were obtained from the total body scan analysis. Venous blood samples were obtained after an overnight fast, centrifuged and the serum frozen at −84o C until the assays were performed. Serum leptin levels were measured in duplicate using a IRMA kit (Diagnostics Systems Laboratory, Webster TX). RESULTS: Postmenopausal women had significantly lower (p<.01) BMD at the femoral neck, trochanter and total hip sites. Serum leptin levels and percent body fat variables were significantly higher (p<.05) in postmenopausal women than in premenopausal women. There were no significant (p>.05) correlations between serum leptin levels and bone density variables across menopausal status. However, leptin was positively related (p<.05) to regional and total measures of percent body fat (r =.64-.72) and fat mass (r =.60-.73). CONCLUSION: Serum leptin levels were not related to bone mineral density or bone mass in sedentary women. The findings of this study confirmed the positive relationship between leptin levels and body fat.