Improved reproducibility of broadband ultrasound attenuation of the os calcis by using a specific region of interest

Quantitative ultrasound (QUS) bone measurement is a promising, relatively new technique for the diagnosis of osteoporosis. Contrary to the more established method of bone densitometry (measurement of bone mineral density, BMD, e.g., using dual X-ray absorptiometry, DEXA), QUS does not employ ionizing radiation. It has, however, been a problem to achieve sufficient reproducibility of the QUS measurements. The aim of this study is to evaluate the possible advantages of measuring broadband ultrasound attenuation (BUA) at a region of interest (ROI) instead of at a fixed position, in terms of in vivo precision and correlation to hip bone mineral density. BUA was measured in 27 premenopausal women, 28 postmenopausal women, an 22 men on the DTU-one. Using high resolution images, a ROI is defined in the posterior part of the os calcis as an area with a local minimum of attenuation and a fixed position within the os calcis is defined relative to the water bath. All BUA measurements were performed twice. BMD at the hip was measured on the QDR-2000. The mean BUA values were significantly different between pre- and postmenopausal women, p = 0.0001 for both the ROI (BUAROI) and the fixed position (BUAFIX). The ROI was found in all subjects and was readily reproducible. The precision at the ROI: 1.20 CV% (95% CI: 1.01-1.29 CV%) was significantly better than at the fixed position: 3.87 CV% (95% CI: 3.23-4.48 CV%). BUAROI (r = 0.64) correlated significantly better than BUAFIX (r = 0.35) with HIP BMD. In conclusion, the use of an imaging technique enables BUA measurements to be performed at a ROI. The precision of BUA at the ROI is significantly better than at the fixed position. BUA measured at the ROI correlates better with HIP BMD than BUA measured at the fixed position.

Circadian variation in bone resorption is not related to serum cortisol

Serum osteocalcin, serum procollagen type I carboxyterminal propeptide (sPICP), and the urinary excretion of pyridinium crosslinks (biochemical markers of bone formation and resorption) all exhibit a circadian variation with a peak during the night. This study was performed to investigate the influence of the endogenous circadian rhythm in cortisol on the biochemical markers of bone turnover. Participants included 11 patients substituted with hydrocortisone due to either hypopituitarism (n = 7) or bilateral adrenalectomy (n = 4). Their daily tablet intake of hydrocortisone was divided in four equal doses in order to abrogate the known circadian variation in cortisol. 24 healthy postmenopausal women served as controls. The study design was performed over 24 h, with blood samples taken every 3 h, and urine collected in 3 h aliquots. Urinary pyridinium crosslinks (Pyr/ Cr, D-Pyr/Cr), serum osteocalcin (sOC), and serum PICP were measured. Patients without a circadian variation in cortisol had normal circadian variation in the urinary excretion of pyridinium crosslinks and sPICP, but no circadian rhythm in serum osteocalcin. We conclude that the etiology of the circadian rhythm in the biochemical markers of bone turnover is still unknown. This study indicates that the circadian variation in sOC can be controlled by the endogenous circadian variation in serum cortisol, whereas this hormone does not control the circadian variation in either the serum PICP or the urinary excretion in pyridinium crosslinks.

[Budesonide and beclamethasone dipropionate inhalation powders. The effect on bone and collagen turnover in children]

The objective of the study was to assess bone and collagen turnover in asthmatic children treated with dry powder budesonide from the Turbohaler and dry powder beclomethasone dipropionate from the Diskhaler in a dose of 800 micrograms/day. Thirteen prepubertal children with asthma were studied. The study was conducted as an open crossover study with two treatment periods and treatment free run-in and wash-out periods. All periods were of two weeks' duration. At day 14 in each period blood samples were taken for assessment of serum osteocalcin, the carboxyterminal propeptide of type I collagen (PICP), and the aminoterminal propeptide of type III collagen (PIIINP). At the same time urine was collected for assessment of creatinine corrected pyridinoline (uPYR/cr) and deoxypyridinoline (udPYR/cr) crosslinks.

RESULTS

Osteocalcin concentrations were not influenced by any of the treatments. During budesonide treatment PICP was reduced by 18% (p = 0.03), PIIINP by 24% (p = 0.0002), uPYR/cr by 16% (p = 0.03) and udPYR/cr by 21% (p = 0.12). During treatment with beclomethasone dipropionate PICP was reduced by 20% (p = 0.01), PIIINP by 36% (p = 0.0002), uPYR/cr by 18% (p = 0.004) and udPYR/cr by 13% (p = 0.02). The suppressive effect of beclomethasone dipropionate on PIIINP was more marked than that of budesonide (p = 0.001). It is concluded that treatment with dry powder budesonide and beclomethasone dipropionate 800 micrograms/day is associated with suppression of bone and collagen turnover. The suppression seems to be more marked during treatment with beclomethasone dipropionate. Long term effects and effects of lower doses of budesonide and beclomethasone dipropionate on bone and collagen markers needs further study.

The response in spinal bone mass to tibolone treatment is related to bone turnover in elderly women

To determine the ability of bone turnover to predict the response in bone mass during treatment with Tibolone, two biochemical markers of bone metabolism were evaluated [CrossLaps corrected for urinary creatinine (CrossLaps/Cr.) and serum osteocalcin measured in a newly developed assay (N-Mid)]. Data from a 2-year double-blind, randomized trial with 56 completing Tibolone-treated women and 13 placebo-treated women were studied. Bone mineral density in the spine (QDR-1000) and indices of bone turnover were determined every 3 months throughout the study. The response in bone mass was calculated as the percent annual change in bone mineral density from baseline and was determined from a total of nine measurements. The response in bone mass was correlated to prestudy values of CrossLaps/Cr. (r = 0.27; p < 0.05), but was uncorrelated to prestudy values of N-Mid. The changes from baseline of these two markers were significantly correlated with the response in bone mass from the 6 months' time point and throughout the rest of the study, i.e., at 1 year: CrossLaps/Cr.: r = 0.54; p < 0.001, N-Mid: r = 0.49; p < 0.001). The change from baseline in the two markers was clearly more predictive of the response in bone mass than the baseline values of these markers as evaluated in a multiple, linear regression-model. Within 1 year of Tibolone-treatment, measured changes in CrossLaps/Cr. and bone mineral density are at least equally predictive of the true response in bone mass over 2 years. These results indicate a possibility of monitoring Tibolone therapy with biochemical markers of bone turnover, at least on group basis.

Development of a monoclonal antibody to urinary degradation products from the C-terminal telopeptide alpha 1 chain of type I collagen. Application in an enzyme immunoassay and comparison to CrossLaps ELISA

A monoclonal antibody MAbA7 was raised against a synthetic peptide having a sequence (EKAHDGGR) specific for a part of the C-telopeptide alpha 1 chain of type I collagen. MAbA7 was labelled with horseradish peroxide and used in a competitive one-step enzyme-linked immunosorbent assay (ELISA) for measurement of urinary type I collagen degradation products. The assay was technically evaluated and preliminary clinical data are presented. The measuring range was 200-7000 micrograms l-1 with a detection limit of 25 micrograms l-1. Within-run and total CVs were 5.5 and 8.0%, respectively. Analytical recovery averaged 96.6% +/- 5.3 (mean +/- 1SD). Values obtained in the ELISA were highly correlated (r = 0.93) to values obtained by a commercially available assay (CrossLaps ELISA) known to measure urinary degradation products derived from the C-telopeptide of type I collagen reflecting the rate of bone resorption. Investigation of the urinary fragments responsible for the immunological response in the two assays revealed, however, that they are not identical. Values obtained in urine samples from postmenopausal women (n = 108) and patients with Paget's disease (n = 6) increased 43% (p < 0.01) and 28-fold (p < 0.001), respectively, when compared to a premenopausal level (n = 50). A decrease in the urinary concentrations of 67% (p < 0.01) was seen after 6 months in urine samples from postmenopausal women (n = 13) receiving hormone replacement therapy (HRT) compared to a group receiving placebo (n = 9). Likewise, the urinary concentrations decreased 88% (p < 0.001) in early postmenopausal women receiving bisphosphonate therapy (n = 11) for a period of 9 months compared to a group receiving placebo (n = 12). These results suggest that the monoclonal antibody and the new assay may be useful for further investigations of the physiological and clinical importance of type I collagen degradation.

Morning or evening administration of nasal calcitonin? Effects on biochemical markers of bone turnover

The purpose of this study was to examine the effect of intranasal salmon calcitonin (sCT) administration (200 IE), given either in the morning (8:00) or evening (21:00), on the known circadian variation in biochemical markers of bone turnover. An open, placebo-controlled, randomized, crossover study, with three 24 h studies of blood samples drawn every third hour and urine collected in 3 h aliquots was undertaken. Subjects consisted of nine healthy postmenopausal women, aged 58 +/- 7 years. Urinary CrossLaps (a measure of bone resorption) was measured by ELISA and corrected for creatinine (Cr). Serum osteocalcin (sOC) was measured by radioimmunoassay (RIA). The first 24 h study was performed without intervention. Prior to this control study the participants were randomized to either morning (8:00) or evening (21:00) sCT (200 IE). sCT administrations were given 4-5 days prior to and during the second study. After a washing-out period of 2 weeks the participants were given 200 IE of sCT at the reverse time of the day 5 days prior to and during the third study. At all timepoints, urinary CrossLaps/Cr exhibited a significant (p < 0.001) circadian rhythm with its zenith in early morning and nadir in late afternoon. Both morning and evening administration of sCT significantly decreased the urinary excretion of CrossLaps/Cr approximately 3-6 h after administration with a subsequent rebound effect. sOC did not exhibit a significant circadian variation and was not affected by the calcitonin. The 24 h mean urinary CrossLaps/Cr and sOC remained unchanged. Both morning and evening sCT significantly decreased the urinary excretion of CrossLaps/Cr 3-6 h after administration, with a rebound effect approximately 12 h later. However, the present study does not indicate that neither evening nor twice-daily administration is superior to morning administration.

Relation of common allelic variation at vitamin D receptor locus to bone mineral density and postmenopausal bone loss: cross sectional and longitudinal population study

OBJECTIVE

To determine whether common allelic variation at the vitamin D receptor locus is related to bone mineral density and postmenopausal bone loss.

DESIGN

Cross sectional and longitudinal population study.

SETTING

Outpatient clinic in research centre.

SUBJECTS

599 healthy women aged 27 to 72 and 125 women with low bone mass aged 55-77 had bone mineral density measured once in the cross sectional study. 136 women aged 45-54 were followed up for 18 years in the longitudinal study.

MAIN OUTCOME MEASURES

Bone mineral density measured at the lumbar spine, hip, and forearm and rate of bone loss at different times over 18 years in relation to vitamin D receptor genotype as defined by the endonucleases ApaI, EsmI, and TaqI.

RESULTS

Vitamin D receptor genotype was not related to bone mineral density at any site. The maximum difference between homozygotes was 1.3% (P = 0.33, n = 723). Women with low bone mineral density had almost the same genotype frequencies as the women with normal bone mineral densities. Vitamin D receptor genotype was not related to early postmenopausal bone loss from age 51 to 53 (mean (SD) total loss at the lower forearm -3.6% (3.6%)), late postmenopausal bone loss from age 63 to 69 (at the hip-6.2% (8.7%)), or to long term postmenopausal loss from age 51 to 69 (at the lower forearm-24.5% (11.4%)).

CONCLUSION

Common allelic variation at the vitamin D receptor locus as defined by the endonucleases ApaI, EsmI, and TaqI is related neither to bone mineral density nor to the rate of bone loss in healthy postmenopausal Danish women.

Effects on muscle of dieting with or without exercise in overweight postmenopausal women

The main aim of this study was to investigate the effect of an energy-restrictive, high-protein diet with or without exercise on muscle morphology and biochemistry. Moderately overweight postmenopausal women (49-58 yr, body mass index: 25-42 kg/m2) were randomly assigned to three groups for 12 wk of intervention; namely, a control group, a group on a 4.2 MJ/day diet, and a group on 4.2 MJ/day diet combined with aerobic and anaerobic exercise. Muscle morphology and biochemistry analysis were performed in 69 and 58 women, respectively. In contrast to the diet-only group, the die-plus- exercise group significantly increased the muscle fiber areas by 20-25%, the number of capillaries per muscle fiber type I by approximately 20%, and the activities of citrate synthase by approximately 35% and hexokinase by approximately 20% (P < 0.05). There were no statistically significant changes in any other muscle variable (P < 0.05). The respiratory exchange ratio decreased in both intervention groups by 2-4% (P < 0.01). It is concluded that 12-wk period of an energy-restrictive high-protein diet was not associated with major changes in muscle morphology or biochemistry. The addition of exercise to the die led to an adaptive increase in muscle fiber areas and in the oxidative capacity of the muscles.

Plasminogen activator inhibitor-1, tissue-type plasminogen activator, and fibrinogen: Effect of dieting with or without exercise in overweight postmenopausal women

This study assessed the short- and long-term effects of an energy-restrictive diet with or without exercise on plasminogen activator inhibitor-1 antigen (PAI-1 Ag) and PAI-1 activity, tissue-type plasminogen activator antigen (TPA Ag), and fibrinogen serum levels. Healthy, overweight postmenopausal women (age, 53.8+/-2.5 years; body mass index, 25 to 42 kg/m2; n=121) were randomly assigned to one of three groups: control, 4200-kJ/d diet, or 4200-kJ/d diet with combined aerobic and anaerobic exercise. PAI-1 activity and PAI-1 Ag, TPA Ag, and fibrinogen levels were measured at baseline, after a 12-week intervention, and after a further 6-month follow-up. PAI-1 Ag and activity and TPA Ag were positively correlated with serum triglyceride levels, the abdominal-to-total-body fat ratio (as assessed by total-body dual-energy x-ray absorptiometry), fasting blood glucose, and systolic BP and negatively with HDL cholesterol and sex hormone-binding globulin. The diet led to profound decreases and normalization of PAI-1 activity (approximately 50%), PAI-1 Ag (approximately 30%) and TPA Ag (approximately (29%), but exercise conferred no additional effect. Fibrinogen did not change. At follow-up there were no longer any significant changes (P>.05). In conclusion, PAI-1 Ag and activity as well as TPA Ag seem to be part of the metabolic syndrome X. The diet made the blood less thrombogenic in the short term with no effect of the added exercise.

Bone mineral density in immigrants from southern China to Denmark. A cross-sectional study

Immigration from Japan to USA has been shown to increase bone mineral density (BMD) and body fat in women. The effects of immigration between other geographical areas on bone mass and body composition are largely unknown, especially in men. In the present study, we measured bone mass and body composition by dual energy X-ray absorptiometry (Hologic QDR-2000) in 73 healthy premenopausal women (age 35 +/- 8 years) and 69 men (age 40 +/- 12 years) who had immigrated from southern China to Denmark 2 months to 36 years ago. The BMD measurements (Total BMD, trunk BMD and leg BMD) were related positively to years since immigration (YSI) (R2 = 0.10-0.16, p < 0.05) in premenopausal women, but not in men. Fat distribution was related mainly to age in both premenopausal women and men (R2 = 0.16-0.26, p < 0.05). For comparison, we included 51 white, Danish premenopausal women (age 36 +/- 6 years). Chinese premenopausal women with a YSI below or equal to 12 years (N = 38) had significantly lower total and regional BMD (trunk, legs, arms) (p < 0.05), while women with a YSI above 12 years (N = 35) had significantly lower BMD in the legs only (p < 0.05) when compared to the Danish premenopausal women. After correction for age weight and height, Chinese premenopausal women with a YSI below or equal to 12 years still had significantly lower BMD in all regions (4-7%, p < 0.05), whereas no differences in BMD were found between Chinese premenopausal women with a YSI above 12 years compared with Danish premenopausal women. In conclusion, Chinese premenopausal women who immigrated to Denmark more than 12 years ago have a similar BMD to that of Danish premenopausal women. In the group who immigrated less than 12 years ago, a significantly lower BMD was found.

Anteroposterior and lateral spinal DXA for the assessment of vertebral body strength: comparison with hip and forearm measurement

Spinal bone mineral density (BMD) is traditionally measured by dual-energy X-ray absorptiometry (DXA) in the anteroposterior (AP) projection which includes both the vertebral body and the posterior elements in the measurement. The posterior elements, however, contribute little to the compressive strength of the spine. It has therefore been suggested that spinal BMD measured in the lateral projection, including only the vertebral body in the measurement, might be more appropriate for the prediction of fracture risk. To date little clinical evidence has been presented to support this assumption. To address the issue, we measured vertebral, hip and forearm BMD in situ in 14 human cadavers and remeasured BMD in vitro in excised vertebrae. Lateral spinal measurements were performed in the decubitus position. Fracture force and other biomechanical measures were determined for 32 vertebrae in a mechanical testing machine and compared with BMD values in situ and in vitro. Correlations of BMD with vertebral fracture force were r = 0.48/0.51 (in situ/in vitro) for the AP spinal measurements, r = 0.45/0.71 (in situ/in vitro) for the lateral spinal measurements, and r = 0.64 and r = 0.53 for total hip and forearm measurements in situ, respectively. Thus, despite an apparent diagnostic advantage in vitro, lateral spinal BMD measurement was not superior to AP measurement when performed in situ. This observation corresponds well with previous clinical findings and is probably due to the larger accuracy error in the lateral than in the AP projection resulting from a lower ratio of bone to soft tissue. The high correlation between hip BMD and vertebral fracture force suggests that hip measurement may prove as useful for vertebral fracture risk assessment as spinal measurement in any projection, especially in the elderly with a high prevalence of degenerative changes in the spine.

Bone and collagen turnover during treatment with inhaled dry powder budesonide and beclomethasone dipropionate

OBJECTIVES

To assess bone and collagen turnover in asthmatic children treated with dry powder budesonide from the Turbuhaler and dry powder beclomethasone dipropionate from the Diskhaler in a dose of 800 micrograms/day.

SUBJECTS

Thirteen prepubertal children with asthma.

DESIGN

Open crossover study with two treatment periods and treatment free run-in and wash-out periods. All periods were of two weeks' duration. At day 14 in each period blood samples were taken for assessment of serum osteocalcin, the carboxyterminal propeptide of type I collagen (PICP), and the aminoterminal propeptide of type III collagen (PIIINP). At the same time urine was collected for assessment of creatinine corrected pyridinoline (uPYR/cr) and deoxypyridinoline (udPYR/cr) crosslinks.

RESULTS

Osteocalcin concentrations were not influenced by any of the treatments. During budesonide treatment mean (SEM) PICP was reduced by 18% (8%) (p = 0.03), PIIINP by 24% (3%) (p = 0.0002), uPYR/cr by 16% (6%) (p = 0.03), and udPYR/cr by 21% (13%) (p = 0.12). During treatment with beclomethasone dipropionate mean (SEM) PICP was reduced by 20% (6%) (p = 0.01), PIIINP by 36% (3%) (p = 0.0002), uPYR/cr by 18% (4%) (p = 0.004), and udPYR by 13% (5%) (p = 0.02). The suppressive effect of beclomethasone dipropionate on PIIINP was more marked than that of budesonide (p = 0.001).

CONCLUSION

Treatment with dry powder budesonide and beclomethasone dipropionate 800 micrograms/day is associated with suppression of bone and collagen turnover. The suppression seems to be more marked during treatment with beclomethasone dipropionate. Long term effects and effects of lower doses of budesonide and beclomethasone dipropionate on bone and collagen markers needs further study.

The effect of menopause and hormone replacement therapy on bone alkaline phosphatase

We evaluated two different assays for the determination of bone-specific alkaline phosphatase (B-AP). One assay was a direct method using a two-site IRMA (AP(Hyb)). The other assay determined B-AP indirectly after precipitation with lectin (AP(BM)). The assays were compared to serum osteocalcin (levels) and total AP in 20 premenopausal women and in 40 early postmenopausal women before and after 9 months of treatment with hormone replacement therapy (HRT) (n = 20) or placebo (n = 20). Serum osteocalcin correlated with serum AP(Hyb) (r = 0.45), and with serum AP(BM) (r = 0.33) (both p < 0.001). The correlation between AP(Hyb) and AP(BM) was moderate, r = 0.71 (p < 0.001). When comparing postmenopausal to premenopausal women, serum osteocalcin had a t score (mean +/- SEM) of 2.30 +/- 0.29 followed by total AP(T-AP) (1.20 +/- 0.28), AP(Hyb) (1.05 +/- 0.33) and AP(BM) (0.64 +/- 0.21) (paired t-test: p < 0.01 for osteocalcin vs. other markers). After 9 months of HRT all markers had declined significantly to premenopausal levels (mean +/- SEM): osteocalcin with 44.5% +/- 6.1%; AP(BM) with 32.1% +/- 5.6%; AP(Hyb) with 36.4% +/- 4.4% and T-AP with 24.4% +/- 2.9%; p < 0.001. Of the markers, only serum osteocalcin correlated significantly with the rate of bone loss in the placebo group (r = 0.52, p < 0.02). We conclude that both assays for B-AP reflect bone turnover in postmenopausal women with and without HRT. Under controlled conditions they did not show any advantage of osteocalcin in diagnosing increased bone turnover or monitoring the effect of an anti-resorptive therapy in postmenopausal women.

Creatinine clearance at menopause is not related to bone mass in later life

OBJECTIVE

To investigate whether creatinine clearance (Ccr) at menopause is related to bone mass later in life.

METHODS

Ccr was measured within 5 years after natural menopause in two groups of normal women. Bone mineral content (BMC) of the distal forearm, lumbar spine, and proximal femur were measured by photon absorptiometry and dual energy X-ray absorptiometry in these women 6 years (n = 47) and 14 years later (n = 98).

RESULTS

Ccr corrected for body surface area just after the menopause did not correlate with BMC, 6.5 years and 14.5 years later.

CONCLUSION

Low Ccr within the normal range at menopause is not an independent risk factor for osteopenia in later life.

The response to treatment of overweight in postmenopausal women is not related to fat distribution

OBJECTIVE

To investigate whether fat distribution or sex hormone status in overweight postmenopausal women do influence the response to treatment of overweight.

DESIGN

Longitudinal, clinical intervention study of a 4.2 MJ diet daily with or without exercise.

SUBJECTS

98 healthy, overweight, postmenopausal women (age: 49-58 y, BMI: 25-42 kg/m2).

MEASUREMENTS

Various fatness and fat distribution parameters (by dual-energy x-ray absorptiometry and anthropometry), sex hormone-binding globulin (SHBG), sex hormones, and the resting energy expenditure (REE) at baseline and after 3 months.

RESULTS

Reductions in weight and fat were independent of the initial fat distribution and the REE, but were significantly associated with high initial SHBG levels. Furthermore, loss of fat was significantly and independently associated with increases in SHBG and reductions in central fat distribution.

CONCLUSION

Postmenopausal women with an android and gynoid fat distribution respond with similar weight loss to treatment of overweight. Furthermore, a more healthy, less android, fat distribution and sex hormone status may be achieved with increasing weight loss.

Changes in the carboxyl-terminal propeptide of type I procollagen and other markers of bone formation upon five days of bed rest

This study was performed in order to investigate the influence of skeletal unloading on the serum concentration of the carboxyl-terminal propeptide of type I procollagen (sPICP) and other markers of bone formation. Blood samples were taken every third hour from nine healthy premenopausal women (22-29 years) in two 24 h studies, before and at the end of five days of bed rest. Furthermore, a set of samples were taken 12 h apart after three days of bed rest. We measured sPICP, the serum concentration of intact and N-terminal-Mid fragment osteocalcin (sOC), and the serum concentration of alkaline phosphatase (sAP). During the five days of bed rest a gradual increase in sOC was observed, while sPICP gradually decreased. sAP was unchanged. Five days of best rest resulted in the following overall changes in the 24 h mean values: sPICP: -14% (p = 0.002); sOC: +9% (p = 0.009); sAP: -1% (not significant). The circadian patterns did not change significantly after bed rest. It is puzzling that the changes in the bone formation markers are of different magnitude, and for sPICP and sOC even in opposite directions. The increase in sOC may be caused by an increase in OC secretion by the osteoblasts or a release of bone-incorporated OC from resorbing sites; the accompanying decrease in sPICP may indicate that bone formation is actually transiently decreased after short term bed rest.

Impact of soft tissue on in vivo accuracy of bone mineral measurements in the spine, hip, and forearm: a human cadaver study

The impact of soft tissue in vivo on accuracy of bone mineral density (BMD) measurements of the spine and hip by dual energy X-ray absorptiometry and of the forearm by single photon absorptiometry was assessed by use of 14 human cadavers. The in vivo accuracy errors (SEE%) were: forearm 3-5%, anteroposterior spine 5.3%, lateral spine 10-12%, and femoral greater trochanter, neck, total, intertrochanteric, and Ward's triangle 3%, 6.5%, 6.7%, 8%, and 11-13%, respectively. Except from the lateral spine and the greater trochanter, the slopes of the linear regressions of in vivo BMD against in vitro BMD were not significantly different from 1 (p > 0.05). The calculated random accuracy error of BMD measurements due to fat inhomogeneity was estimated to 3-4% for the anteroposterior spine and 9-14% for the lateral spine (from abdominal computed tomography in 26 healthy women). In conclusion, acceptable accuracy errors below 6-7% (of soft tissue in vivo) of BMD measurements were obtained in the anteroposterior spine, the forearm, and the neck, greater trochanter, and total proximal femur.

Age- and menopause-associated variations in body composition and fat distribution in healthy women as measured by dual-energy X-ray absorptiometry

To assess the variation with age and menopause, 407 healthy normal women aged 18 to 75 years had body composition and fat distribution measured by dual-energy x-ray absorptiometry (DEXA). The mean +/- SD are given for different age decades. Postmenopausal women had significantly more fat, a more central fat distribution, and less lean tissue mass (LTM) than premenopausal women. In premenopausal and postmenopausal women, age only correlated with the abdominal to total-body fat tissue ratio (r approximately .24, P < .05), whereas the years since onset of menopause correlated with fat tissue mass (FTM), fat%, abdominal fat%, and the abdominal to total-body fat tissue ratio (r approximately .2, P < .05). To assess the independent impact of age, menopausal status, and years since menopause, multiple linear regressions were performed. FTM, fat%, and abdominal fat% were significantly related to menopausal status and years since menopause independently of age. The abdominal to total-body fat tissue ratio was statistically significantly related to age, but tended also to be independently related to years since menopause. LTM was statistically significantly related to menopausal status independently of age and years since menopause. In summary, we suggest that in healthy women total-body and abdominal fat may increase and LTM may decrease in the years after menopause, primarily in the perimenopausal years, without significant changes before menopause.

Dual energy X-ray absorptiometry of the spine--decubitus lateral versus anteroposterior projection in osteoporotic women: comparison to single energy X-ray absorptiometry of the forearm

We investigated the discriminatory ability of dual energy X-ray absorptiometry (DXA) of the lumbar spine in the anteroposterior vs. decubitus lateral projection in 53 elderly women with at least one vertebral fracture and 63 age-matched women without fracture. Twenty-three premenopausal healthy women served as a reference group. Spine measurements were compared to forearm measurements by single energy X-ray absorptiometry (SXA). Bone mineral density (BMD) of the women with fractures was 16% lower in the AP projection and 17% lower in the decubitus lateral projection compared to age-matched women without fractures. t-Scores (deviation from normal premenopausal values in SDs) were -2.1 to -2.3 in the women without fractures, and -3.9 (AP projection), -3.1 (lateral projection) and -3.8 (forearm) in the women with vertebral fractures. t-Scores as well as z-scores for bone mineral content of the vertebral body and the vertebral posterior elements (both measured with the lateral projection) were similar. ROC analysis showed no significant difference between the AP and the lateral projection of the spine. When subjects with vertebral endplate sclerosis (about 25% in each group, with considerably elevated spinal BMD) were excluded, it did not significantly change the diagnostic abilities for fractures. We found no diagnostic advantage of the lateral projection as compared to the AP projection or forearm measurement. Future studies will reveal whether absorptiometry in the lateral projection can be improved by supine lateral scanning.

Circadian rhythm in type I collagen formation in postmenopausal women with and without osteopenia

A circadian rhythm in the serum concentration of the procollagen type I carboxyl-terminal propeptide (sPICP) has previously been demonstrated in premenopausal women. This study was performed to investigate the circadian rhythm in sPICP in healthy and osteopenic postmenopausal women. Blood samples were taken every third hour for 27 h from three groups of women: 12 early postmenopausal women (aged 55 +/- 2 years; mean +/- SD); 12 late postmenopausal women (aged 73 +/- 1 years); and 12 osteopenic but otherwise healthy late postmenopausal women (aged 73 +/- 1 years). A circadian rhythm in sPICP was found in all three groups, as shown by cosinor analysis (p = 0.000003-0.03). The circadian rhythm in sPICP was significantly different between the osteopenic group and the age-matched healthy group (p < 0.008). The amplitude of the circadian rhythm in sPICP was about twice as high in the osteopenic group, and the time of the maximum tended to be about 3 h later, as compared with the age-matched healthy group. The plasma concentration of osteocalcin, as measured by a recently developed two-site enzyme-linked immunosorbent assay, also showed a circadian rhythm in all three groups (p = 0.0001-0.05), with no significant differences between groups. In conclusion, we have found a significant circadian rhythm in sPICP in both early and late postmenopausal women. In osteopenic women the nightly peak in sPICP is larger and persists later into the night as compared with non-osteopenic women.

Early postmenopausal diminution of forearm and spinal bone mineral density: a cross-sectional study

Diminution of bone mineral density (BMD) in the spine and forearm was studied cross-sectionally in 363 women who were 6 months to 10 years postmenopausal. BMD was determined by dual-energy X-ray absorptiometry (DXA) (Hologic QDR-2000) in the lumbar spine, in both the supine lateral (LAT) and anteroposterior (AP) projections, and in the distal third of the forearm. The postmenopausal diminution of BMD was best described by an exponential fit. The initial rate of postmenopausal diminution of BMD was highest in the most trabecular sites (LAT > AP > forearm), but 10-year diminution was similar at all sites (12%-13%, corresponding to about 1.0-1.5 SD), and extrapolation suggested reverse order of the rates of diminution thereafter (forearm > AP > LAT). When bone mineral content of the entire L3 vertebra (tBMC) was measured in vivo, AP tBMC could account for only 67% of the variation in LAT tBMC, compared with r2 = 0.997 in vitro. This observation suggests an accuracy problem in vivo in one of the spine measurement methods. We conclude that the initial rate of BMD diminution after the menopause seems to be highest in the spine, especially when measured laterally, but that this rate levels off within the first decade. The lower precision error of a forearm measurement (0.8% v 1.6 for AP and 3.1 for LAT) therefore implies that this method may require a shorter observation period than spine measurements for the detection of bone loss 5-10 years after menopause. Long-term longitudinal spine and forearm measurements are, however, needed to confirm these conclusions.

Posture, age, menopause, and osteopenia do not influence the circadian variation in the urinary excretion of pyridinium crosslinks

This study was performed to investigate whether the circadian variation in urinary pyridinium crosslinks is related to physical activity, age, the menopause, and asymptomatic osteopenia. We measured urinary pyridinoline/creatinine (Pyr/Cr) and deoxypyridinoline/creatinine (D-Pyr/Cr) in 9 healthy premenopausal women in two 27 h studies, before and at the end of 5 days of total bed rest. Both Pyr/Cr and D-Pyr/Cr showed highly significant circadian variations, with the peak at night and the nadir during the day (p < 0.001). The 5 days of complete bed rest produced no changes in the circadian pattern, but a general increase of 28% was observed in pyridinium crosslinks. A group of 12 healthy, early postmenopausal women (aged 55 +/- 2 years), 12 healthy, elderly postmenopausal women (aged 73 +/- 1 years), and 12 elderly osteopenic but otherwise healthy women (aged 73 +/- 1 years) were also studied for 27 h. All three groups showed highly significant (p < or = 0.001) circadian variations in the urinary excretion of pyridinium crosslinks. As expected, both Pyr/Cr (p < 0.05) and D-Pyr/Cr (p < 0.001) increased at the time of menopause, but the circadian variations in Pyr/Cr and D-Pyr/Cr were similar in all groups studied. We conclude that the circadian variation in the urinary excretion of pyridinium crosslinks is independent of physical factors. Furthermore, the circadian variation in pyridinium crosslinks was not related to age, menopausal status, or asymptomatic osteopenia.