Bone Turnover In Elderly Women Research Articles

Differences in exposure to stimulatory and inhibitory components of the insulin-like growth factor (IGF) system in patients with femoral neck versus trochanteric fracture

SIR—Bone loss, the major determinant of hip fracture risk in the elderly [1], results from an increased rate of bone turnover [2] that will amplify the imbalance at the level of the individual remodelling unit. However, while the increase in bone turnover in elderly women results in part from secondary hyperparathyroidism [3], the mechanisms responsible for the age-related decline in bone formation have not yet been identified.

Effects of vitamin D metabolites on intestinal calcium absorption and bone turnover in elderly women

The relative importance of vitamin D metabolites in the regulation of gut calcium absorption has not been well studied in elderly women living in an environment with abundant sunlight. The objective was to examine the determinants of active gut calcium absorption ( +/- SD: 42 +/- 11%) after an overnight fast with the use of a low (10 mg) calcium load. One hundred twenty elderly women aged 74.7 +/- 2.6 y underwent an active calcium absorption test with a radioactive calcium tracer, dietary analysis, and measurement of markers of bone turnover and calcium metabolism. The mean serum 25-hydroxyvitamin D [25(OH)D] concentration at the time of the calcium absorption test was 68 +/- 29 nmol/L. Gut calcium absorption was correlated with 25(OH)D but not 1,25-dihydroxyvitamin D (calcitriol), the free calcitriol index, or dietary calcium intake. After adjustment for age, calcitriol concentration, and dietary calcium intake, the significant determinant of fractional calcium absorption was the 25(OH)D concentration (r = 0.34, P = 0.001). When body weight was included in the regression, both 25(OH)D (beta = 1.20 x 10(-3)) and calcitriol (beta = 1.00 x 10(-3)) were significantly correlated with calcium absorption. Despite the strong relation between 25(OH)D and gut calcium absorption, there was no relation with other aspects of bone turnover or calcium metabolism. These data suggest that at low calcium loads, 25(OH)D is a more important determinant of gut calcium absorption than is calcitriol in elderly women exposed to abundant sunlight, but that this relation has little effect on overall calcium metabolism.

Effects of age and estrogen status on serum parathyroid hormone levels and biochemical markers of bone turnover in women: a population-based study.

Although estrogen deficiency is responsible for the increase in bone turnover in early postmenopausal women, age-related factors, such as the progressive increase in serum PTH levels, are believed to be responsible for the increase in bone turnover in elderly women. Whether estrogen deficiency continues to play a role, either directly or indirectly, in the pathogenesis of the increased bone turnover in elderly women remains unclear. Thus, we measured serum PTH, markers of bone turnover, and serum sex steroid levels in a population-based sample of 351 women (age range, 21-94 yr), which included 47 postmenopausal women who were receiving long term estrogen replacement therapy. Serum PTH increased as a function of age when the premenopausal women and the estrogen-deficient postmenopausal women were analyzed together (r = 0.35; P < 0.001). By contrast, this age-related increase in serum PTH was eliminated in the postmenopausal women receiving long term estrogen therapy, which also resulted in a similar suppression of markers of bone formation and resorption in both the early (< or = 20 yr) and late (> 20 yr) postmenopausal women. By multivariate analysis, serum 25-hydroxyvitamin D levels were highly predictive of serum PTH levels regardless of menopausal status, whereas serum estrone levels were predictive of markers of bone resorption in the postmenopausal women. We conclude that estrogen deficiency may be responsible not only for the increase in bone turnover in early postmenopausal women, but also indirectly for the secondary hyperparathyroidism and increase in bone turnover found in late postmenopausal women. Residual serum estrogen levels are important determinants of bone resorption in postmenopausal women.

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 TM corrected for urinary creatinine (Cross-Laps TM/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 TM/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 TM/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 TM/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.

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

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

Impairment of bone turnover in elderly women with hip fracture

Hip fracture is one of the most severe consequences of osteoporosis affecting aged women. However, abnormalities of bone turnover responsible for bone loss in this condition have not been clearly defined. To further evaluate the bone metabolic status of women sustaining hip fracture, we have prospectively measured serum osteocalcin as a marker of bone formation and urinary excretion of pyridinoline (Pyr) and deoxypyridinoline (D-pyr) cross-links as markers of bone collagen degradation in 174 independently living women (80 +/- 8 years) within a few hours after a hip fracture. Comparison was made with 77 age-matched controls (80 +/- 5 years) and 17 premenopausal women (39 +/- 3 years). In addition 15 of the patients were followed with daily measurements during the first postoperative week. At the time of admission osteocalcin was 20% lower in the fractured women compared to the elderly controls (7.6 +/- 3.8 vs. 9.5 +/- 4.5 ng/ml, P = 0.001). Pyr and D-pyr were 36% and 40% higher, respectively (P = 0.0001), than in elderly controls and 85% and 76% higher than in premenopausal controls (P = 0.0001). Serum osteocalcin did not correlate with the cortisol level measured at the same time (r = 0.03, ns), nor with serum albumin and creatinine. Serum osteocalcin remained unchanged within 18 hours after fracture, whereafter it progressively decreased until the third postoperative day. No correlation was noted between the excretion of pyridinoline cross-links and the time elapsed from fracture.(ABSTRACT TRUNCATED AT 250 WORDS)

Biochemical markers of bone turnover for the clinical investigation of osteoporosis.

The non-invasive assessment of bone turnover has received increasing attention over the past few years because of the need for sensitive markers in the clinical investigation of osteoporosis. Markers of bone formation include the serum measurement of total and bone-specific alkaline phosphatase, osteocalcin, and type I collagen extension peptides. Assessment of bone resorption can be achieved by measurement of urinary hydroxyproline, urinary excretion of the pyridinium crosslinks (pyridinoline and deoxypyridinoline), and by measurement of plasma tartrate-resistant acid phosphatase activity. For the screening of bone turnover in women at the menopause, and for the assessment of the level of bone turnover in elderly women with vertebral osteoporosis, serum osteocalcin and urinary pyridinoline appear to be the most sensitive markers, so far. Programs combining bone mass measurement and assessment of bone turnover by several markers in women at the time of menopause are being developed in an attempt to improve the assessment of the risk for osteoporosis. Efforts are made to develop more convenient assays and to identify other markers of bone turnover. In future a battery of various specific markers is likely to improve the assessment of the complex and subtle abnormalities of bone metabolism that characterize the various aspects of osteoporosis.

3 What do we know about biochemical bone markers?

The non-invasive assessment of bone turnover has received increasing attention over the past few years because of the need for sensitive markers in the clinical investigation of osteoporosis. Markers of bone formation include serum total and bone-specific alkaline phosphatase, serum osteocalcin, and measurement of serum type I collagen extension peptides. Assessment of bone resorption can be achieved with measurement of urinary hydroxyproline, urinary excretion of the pyridinium crosslinks (Pyr and D-Pyr), and by measurement of plasma TRAP activity. For the screening of bone turnover in women at the menopause, and for the assessment of the level of bone turnover in elderly women with vertebral osteoporosis, serum osteocalcin and urinary Pyr and D-Pyr appear to be the most sensitive markers so far. Programmes combining bone mass measurement and assessment of bone turnover in women at the time of the menopause have been developed in an attempt to improve the assessment of the risk for osteoporosis. Efforts are being made to develop more convenient assays and to identify other markers of bone turnover. In the future a battery of various specific markers is likely to improve the assessment of the complex aspects of bone metabolism, especially in osteoporosis.

Urinary excretion of pyridinoline crosslinks correlates with bone turnover measured on iliac crest biopsy in patients with vertebral osteoporosis

Vertebral osteoporosis, a common disorder in elderly women, is characterized by a wide spectrum of bone turnover abnormalities on iliac crest biopsy. The level of bone formation can be assessed noninvasively by measuring serum osteocalcin, whereas conventional biochemical markers of bone resorption lack specificity and do not reflect bone resorption assessed from histology. We measured the urinary excretion of pyridinoline crosslinks Pyr and D-Pyr, a specific marker of bone and cartilage collagen degradation, along with serum osteocalcin and urinary hydroxyproline, in 36 elderly women with vertebral osteoporosis who had a simultaneous iliac crest biopsy. Urinary pyridinoline crosslinks, but not hydroxyproline, correlated significantly with histologic resorption, assessed by the osteoclast surface (r = 0.35, p less than 0.05 for Pyr; r = 0.46, p less than 0.01 for D-Pyr). In addition, Pyr and D-Pyr were correlated with the bone formation rate as well as serum osteocalcin, with correlation coefficients ranging from 0.69 to 0.80, p less than 0.0001. These data indicate that Pyr and D-Pyr are sensitive markers of bone turnover in elderly women with vertebral osteoporosis. The poor correlation between the level of urinary collagen crosslinks and histological assessment of bone resorption indicates the low sensitivity of iliac crest histomorphometry in the measurement of resorption rate of the skeleton.