Indices of calcium metabolism in women with hip fractures

Bone metabolism subgroups identified as hip fracture patients via clustering

PURPOSE

The aim of the study was to describe the bone metabolism status that underlies a hip fracture.

METHODS

Estimated glomerular filtration rate (e-GFR), calcium (Ca), phosphorus (P), total (ALP) and bone specific alkaline phosphatase (b-ALP), intact parathyroid hormone (i-PTH), 25-hydroxy-vitamin D (25OHD), total procollagen type I amino-terminal propeptide (PINP), and N-terminal peptide of collagen I (NTx), measured at admission in 272 hip fracture patients, were ex post analyzed by K-means clustering and principal component analysis and were evaluated by a clinician.

RESULTS

Four components, mainly consisting of b-ALP, PINP, ALP, and NTx; e-GFR and P; i-PTH and 25OHD; and Ca explained about 70% of the variability. A total of 184 patients clustered around a centroid (A) with low 25OHD (13.2 ng/ml), well-preserved kidney function (e-GFR=67.19 ml/min/1.73m²), normal Ca, P, i-PTH and bone markers, with the exception of slightly increased NTx (24.82nMBCE). Cluster B (n=70) had increased i-PTH (93.38 pg/ml), moderately decreased e-GFR, very low 25OHD (8.68 ng/dl), and high bone turnover (b-ALP 28.46 U/L, PINP 69.87 ng/ml, NTx 31.3nMBCE). Cluster C (n=17) also had hyperparathyroidism (80.35 pg/ml) and hypovitaminosis D (9.15 ng/ml), low e-GFR(48.89 ml/min/1.73m²), and notably high ALP (173 U/L) and bone markers (b-ALP 44.64 U/L, PINP 186.98 ng/ml, NTx 38.28nMBCE). According to the clinician, 62 cases clearly had secondary hyperparathyroidism.

CONCLUSIONS

Based on serum measurements, the dominant patterns of bone metabolism were normal bone turnover with high normal NTx, and secondary hyperparathyroidism related to chronic kidney disease and hypovitaminosis D. The bone formation markers, e-GFR, NTx, and P composed the most important factors.

Is there a role for vitamin D in supporting cognitive function as we age?

Globally, an estimated 46 million people are currently living with dementia and this figure is projected to increase 3-fold by 2050, highlighting this major public health concern and its substantial associated healthcare costs. With pharmacological treatment yet to reach fruition, the emphasis on evidence-based preventative lifestyle strategies is becoming increasingly important and several modifiable lifestyle factors have been identified that may preserve cognitive health. These include good cardiovascular health, physical activity, low alcohol intake, smoking and a healthy diet, with growing interest in vitamin D. The aim of the present paper is to review the evidence supporting the potential roles of vitamin D in ageing and cognitive health in community-dwelling older adults. Furthermore, to describe the utility and challenges of cognitive assessments and outcomes when investigating vitamin D in this context. Evidence indicates that serum 25-hydroxyvitamin D (25(OH)D) may impact brain health. There is a biological plausibility from animal models that vitamin D may influence neurodegenerative disorders, through several mechanisms. Epidemiological evidence supports associations between low serum 25(OH)D concentrations and poorer cognitive performance in community-dwelling older populations, although an optimal 25(OH)D level for cognitive health could not be determined. The effect of raising 25(OH)D concentrations on cognitive function remains unclear, as there is a paucity of interventional evidence. At a minimum, it seems prudent to aim to prevent vitamin D deficiency in older adults, with other known common protective lifestyle factors, as a viable component of brain health strategies.

The biochemical and histological analysis of subcutaneous calcitonin and intramedullary methylprednisolone on bone repair after bone marrow ablation: an experimental comparative study in rats

Background

Although, glucocorticoid (GC) and calcitonin-induced changes in bone repair have been studied previously, the exact effects of these on fracture healing remain controversial. Hence, the purpose of this experimental study is to determine biochemical and histological effects of locally administrated GC and systemically administrated calcitonin on the kinetics of healing response after bone marrow ablation in rats.

Methods

After having undergone marrow ablation, a steroid-treated group of rats (n = 24) received a single dose of intramedullary methylprednisolone (2 mg/kg), a calcitonin-treated group (n = 24) received intermittently administrated subcutaneous salmon calcitonin (16 IU/kg), and a control group (n = 24) received intramedullary saline (25 μl).

Results

Blood samples taken on days 1, 3, 7, 9, and 15 after ablation showed an increase in serum calcium, alkaline phosphatase (ALP), and phosphate levels in the Calcitonin and Control groups. Levels of calcium and ALP peaked on day 7 after ablation. However, an increase in phosphate levels indicated a biphasic reaction that peaked on the third and ninth day after ablation. Hypercalcemia was not observed in Steroid group because of the inhibition of osteoclastic bone resorption. In that group, the serum levels of ALP and phosphate were lower than baseline levels. The levels of urinary calcium excretion peaked 3 to 7 days after marrow ablation in the control group and 7 to 9 days after that procedure in the steroid group. Histologic evaluation showed that the rats in the control group demonstrated the expected healing period according to the histological grades and that a delay in healing occurred in the calcitonin group after day 9 because of the inhibition of osteoclastic bone resorption. All rats in the steroid group exhibited a decrease and delayed healing response.

Conclusion

Total serum calcium, phosphate, and ALP levels increased after bilateral tibial bone marrow ablation and urine calcium and hydroxyproline excretion also increased as a factor of bone resorption. Subcutaneously administrated salmon calcitonin did not affect biochemical changes after marrow ablation. Single-dose intramedullary methylprednisolone inhibited extra-tibial bone resorption induced by cytokines after bone marrow ablation.

Efficacy of optimization of vitamin D in preventing osteoporosis and osteoporotic fractures: A systematic review

Increased intake or supplementation of vitamin D is often recommended for normal bone health; however, its preventive effect on osteoporosis has not been fully evaluated. The aim of this review is to gather evidence of the efficacy of the optimization of vitamin D nutrition in preventing osteoporosis and osteoporotic fractures. PubMed was used for searching the relevant literature using the MeSH terms "Bone Density (limited to "human", "female", and "English" literature)" or "Fractures (limited to "human", "age ≥45 years", and "English" literature)", and "Vitamin D". The searches yielded 19 randomized controlled trials (RCTs), nine cohort studies, 19 case-control studies, 19 cross-sectional studies, and one meta-analysis. We attempted to answer three questions: 1) does increased vitamin D intake prevent bone loss in peri- and postmenopausal women?, 2) does increased vitamin D intake prevent osteoporotic fractures in the elderly?, and 3) does increased vitamin D in take positively affect peak bone mass attainment in young women? The answer to questions 1 and 2 is that a vitamin D intake of 10-17.5 μg/day (400-700 IU/day) or more is effective in preventing bone loss in late postmenopausal women and an intake of 17.5-20 μg/day (700-800 IU/day) or more together with a calcium supplement reduces the risk of osteoporotic fractures. For question 3, some lines of evidence support the negative effect of low vitamin D nutrition on the attainment of peak bone mass in young women. Further studies are needed to clarify the effect of vitamin D in this age group.

Vitamin D and osteoporosis-related fracture

The age-related decline in mass and quality of bone (osteoporosis) and muscle (sarcopenia) leads to an exponential increased risk for osteoporosis-related fracture with advancing age in older adults. As vitamin D inadequacy plausibly causally contributes to these declines, optimization of vitamin D status might reduce the deterioration of bone and muscle function with age. Putative mechanisms by which vitamin D inadequacy may increase fracture risk include both direct and indirect effects on bone and muscle. However, controversy currently clouds the role(s) of vitamin D in osteoporosis-related fracture, the amount of vitamin D required and the optimal 25-hydroxyvitamin D level. This review provides an overview of current knowledge and suggests a clinical approach to vitamin D status in older adults with, or at risk for, osteoporosis-related fracture. These recommendations are likely to evolve as additional data becomes available.

[Vitamin D and bone health: is there a need to review supplementation in osteoporosis risk population?]

Vitamin D is an essential hormone for achieving an optimal bone physiology. There is no universal consensus nowadays on the definition of hypovitaminosis D and cut-off values have been refined in the last years. The aim of this review is to analyze vitamin D deficiency among osteoporosis risk populations, including elderly and postmenopausal women, in Spain and other countries. We also review vitamin D supplementation: current clinical guidelines, last clinical studies, safety, and prescription schemes.

Vitamin D and the elderly

This review summarizes current knowledge on vitamin D status in the elderly with special attention to definition and prevalence of vitamin D insufficiency and deficiency, relationships between vitamin D status and various diseases common in the elderly, and the effects of intervention with vitamin D or vitamin D and calcium. Individual vitamin D status is usually estimated by measuring plasma 25-hydroxyvitamin D (25OHD) levels. However, reference values from normal populations are not applicable for the definition of vitamin D insufficiency or deficiency. Instead vitamin D insufficiency is defined as the lowest threshold value for plasma 25OHD (around 50 nmol/l) that prevents secondary hyperparathyroidism, increased bone turnover, bone mineral loss, or seasonal variations in plasma PTH. Vitamin D deficiency is defined as values below 25 nmol/l. Using these definitions vitamin D deficiency is common among community-dwelling elderly in the developed countries at higher latitudes and very common among institutionalized elderly, geriatric patients and patients with hip fractures. Vitamin D deficiency is an established risk factor for osteoporosis, falls and fractures. Clinical trials have demonstrated that 800 IU (20 microg) per day of vitamin D in combination with 1200 mg calcium effectively reduces the risk of falls and fractures in institutionalized patients. Furthermore, 400 IU (10 microg) per day in combination with 1000 mg calcium or 100 000 IU orally every fourth month without calcium reduces fracture risk in individuals over 65 years of age living at home. Yearly injections of vitamin D seem to have no effect on fracture risk probably because of reduced bioavailability. Simulation studies suggest that fortification of food cannot provide sufficient vitamin D to the elderly without exceeding present conventional safety levels for children. A combination of fortification and individual supplementation is proposed. It is argued that all official programmes should be evaluated scientifically. Epidemiological studies suggest that vitamin D insufficiency is related to a number of other disorders frequently observed among the elderly, such as breast, prostate and colon cancers, type 2 diabetes, and cardiovascular disorders including hypertension. However, apart from hypertension, causality has not been established through randomized intervention studies. It seems that 800 IU (20 microg) vitamin D per day in combination with calcium reduces systolic blood pressure in elderly women.

Vitamin D status and bone turnover in women with acute hip fracture

Hypovitaminosis D is common in elderly women. Few data are available on vitamin D status and bone turnover in women with acute hip fracture. The aims of this study were to determine whether elderly Italian women with an acute hip fracture also had low vitamin D levels and an increase of bone turnover compared with elderly women with osteoporosis but without fractures. Seventy-four women with acute osteoporotic hip fracture and 73 women with postmenopausal osteoporosis were studied. All women were self-sufficient and had adequate sunlight exposure. To exclude the effect of trauma on serum 25-hydroxycolecalciferol levels and bone markers (bone alkaline phosphatase and C-terminal telopeptides of Type I collagen as indices of bone formation and bone resorption), blood samples were drawn within 24 hours of the fracture. Current data indicated that in our patients the prevalence of hypovitaminosis D is common although to a lesser extent than in women who are housebound. Women with acute hip fractures had a higher prevalence of vitamin deficiency defined as serum 25-hydroxycolecalciferol lower than 12 ng/mL, compared with women with osteoporosis. Moreover, the presence of fracture did not influence the rate of bone formation, whereas the increase in bone resorption could be attributed to an older age of women with acute hip fracture because of similar values of parathyroid hormone levels in the two groups.

Vitamin D deficiency and secondary hyperparathyroidism in the elderly: consequences for bone loss and fractures and therapeutic implications

Vitamin D deficiency is common in the elderly, especially in the housebound and in geriatric patients. The establishment of strict diagnostic criteria is hampered by differences in assay methods for 25-hydroxyvitamin D. The synthesis of vitamin D3 in the skin under influence of UV light decreases with aging due to insufficient sunlight exposure, and a decreased functional capacity of the skin. The diet contains a minor part of the vitamin D requirement. Vitamin D deficiency in the elderly is less common in the United States than elsewhere due to the fortification of milk and use of supplements. Deficiency in vitamin D causes secondary hyperparathyroidism, high bone turnover, bone loss, mineralization defects, and hip and other fractures. Less certain consequences include myopathy and falls. A diet low in calcium may cause an increased turnover of vitamin D metabolites and thereby aggravate vitamin D deficiency. Prevention is feasible by UV light exposure, food fortification, and supplements. Vitamin D3 supplementation causes a decrease of the serum PTH concentration, a decrease of bone turnover, and an increase of bone mineral density. Vitamin D3 and calcium may decrease the incidence of hip and other peripheral fractures in nursing home residents. Vitamin D3 is recommended in housebound elderly, and it may be cost-effective in hip fracture prevention in selected risk groups.

Serum and urine markers of bone metabolism during the year after hip fracture

OBJECTIVE

As part of a larger study to describe indices of recovery during the year after hip fracture, the current prospective study investigated longitudinal changes in serum and urine markers of bone metabolism for the year after hip fracture and related them to bone mineral density (BMD).

DESIGN

A representative subset of participants provided serum and urine samples and had bone density measured at 3, 10, 60, 180, and 365 days postfracture.

SETTING

Two Baltimore hospitals.

PARTICIPANTS

The subjects were 205 community-dwelling, white women age 65 and older with fresh proximal femur fractures.

MEASUREMENTS

Samples were assayed for specific bone-related proteins and bone turnover markers, including serum osteocalcin (OC), procollagen type 1 carboxy-terminal extension peptide (PICP), bone-specific alkaline phosphatase (BAP), and urinary deoxypyridinoline (DPD) cross-links. Selected hormonal regulators of bone metabolism, including parathyroid hormone (PTH), calcitonin (CT), 1,25-dihydroxy vitamin D(3) (1,25 (OH)(2)D), and estrone (E(1)) were measured from serum samples. Repeated measures analyses were used to evaluate postfracture changes in each of the markers.

RESULTS

BAP, OC, and PICP were most active during the early postfracture period (3-60 days). BAP and OC remained elevated at 365 days compared with 3 days. DPD rose 48% from 3 days to 60 days, but this difference was not statistically significant. PTH and 1,25 (OH)(2)D increased steadily and significantly from 3 to 365 days. E(1) was highest at baseline and decreased at each time point, whereas CT showed no significant changes. When subjects were stratified into high-, medium-, and low-BMD groups based on their measurement at 3 days, both osteoclastic and osteoblastic markers in the low-BMD group displayed exaggerated and different patterns over time compared with the other groups.

CONCLUSION

Currently, the standard treatment of care for hip fractures still results in high morbidity and mortality and failure to regain prefracture quality of life. Gaining an understanding of bone cell activity in these patients after hip fracture, derived by measuring markers longitudinally during recovery, provides a baseline by which to measure the effectiveness of new interventions to improve recovery from hip fracture.

Hyperparathyroidism is augmented by ovariectomy in Nagase analbuminemic rats

The role of albumin in bone metabolism was studied in Nagase analbuminemic (NA) rats. Serum calcium (Ca), inorganic phosphate (Pi) and magnesium (Mg) concentrations did not differ between female NA and control Sprague-Dawley (SD) rats at the time of ovariectomy (ovx), although serum ionized Ca was significantly lower in NA rats than in SD rats. Serum parathyroid hormone (PTH) and osteocalcin (OC) concentrations and urinary Ca excretion were significantly greater in NA rats than in SD rats, suggesting hyperparathyroidism and the resultant enhanced bone turnover in NA rats. Paradoxically, ovx increased serum PTH and OC in NA rats but not in SD rats. Ovx-induced exacerbation of hyperparathyroidism was confirmed by significantly greater conversion of 25-hydroxyvitamin D to 1, 25-dihydroxyvitamin D in ovx NA rats even after normalization to vitamin D-binding protein. Bone mineral density (BMD) in proximal tibia increased similarly in a time-dependent manner in sham-operated NA and SD rats. However, ovx ablated the time-dependent increase of BMD in SD rats and significantly decreased BMD in NA rats by 2 wk after ovx, resulting in a significantly lower BMD in ovx NA rats than in ovx SD rats. In summary, NA rats, which are analbuminemic with compensatory increases in lipid and protein synthesis, developed hyperparathyroidism, possibly due to an increase in serum Pi and a reduction of ionized Ca, and ovx induced a greater BMD reduction in NA rats than in SD rats, probably by exacerbating hyperparathyroidism.

Calcium, dairy products and osteoporosis

Osteoporosis is a multifactorial disorder in which nutrition plays a role but does not account for the totality of the problem. 139 papers published since 1975 and describing studies of the relationship of calcium intake and bone health are briefly analyzed. Of 52 investigator-controlled calcium intervention studies, all but two showed better bone balance at high intakes, or greater bone gain during growth, or reduced bone loss in the elderly, or reduced fracture risk. This evidence firmly establishes that high calcium intakes promote bone health. Additionally, three-fourths of 86 observational studies were also positive, indicating that the causal link established in investigator-controlled trials can be found in free-living subjects as well. The principal reason for failure to find an association in observational studies is the weakness of the methods available for estimating long-term calcium intake. While most of the investigator-controlled studies used calcium supplements, six used dairy sources of calcium; all were positive. Most of the observational studies were based on dairy calcium also, since at the time the studies were done, higher calcium intakes meant higher dairy intakes. All studies evaluating the issue reported substantial augmentation of the osteoprotective effect of estrogen by high calcium intakes. Discussion is provided in regard to the multifactorial complexity of osteoporotic response to interventions and to the perturbing effect in controlled trials of the bone remodeling transient, as well as about how inferences can validly be drawn from the various study types represented in this compilation.

Down-regulation of the serum stimulatory components of the insulin-like growth factor (IGF) system (IGF-I, IGF-II, IGF binding protein [BP]-3, and IGFBP-5) in age-related (type II) femoral neck osteoporosis

Both a decrease in bone formation and an increase in bone resorption have been implicated in the pathogenesis of age-related (type II) femoral neck osteoporosis. While the increase in the bone resorption rate has been shown to be partially related to secondary hyperparathyroidism, the mechanisms underlying the decline in bone formation have not yet been identified. The aim of the present study was to test the hypothesis that the bone formation deficit associated with type II osteoporosis might be due to secondary hyperparathyroidism and/or to a deficiency of the insulin-like growth factor (IGF) system. Circulating concentrations of IGF-I, IGF-II, IGF binding protein (IGFBP)-3, IGFBP-4, IGFBP-5, 25-hydroxycholecalciferol (25(OH)D3), and intact parathyroid hormone (PTH) were measured in 50 elderly women after sustaining a hip fracture and in 50 healthy age-matched controls. In addition, serum levels of osteocalcin (OC), skeletal alkaline phosphatase, and N-terminal procollagen peptide and urinary pyridinium cross-links were determined as markers of bone remodeling, and bone mineral density (BMD) was assessed at the proximal femur. In the patient group, serum was drawn within 18 h of the fracture and prior to surgery. Circulating protein concentrations did not change over this time frame. No difference was found between mean IGFBP-4 serum levels in the two groups studied, while mean levels of IGF-I, IGF-II, IGFBP-3, IGFBP-5, 25(OH)D3, and markers of bone formation were significantly lower (p < 0.006) in patients as compared with healthy subjects. Serum PTH and urinary pyridinium cross-links, however, were markedly increased (p < 0.001) in the osteoporotic group. In pooled data from the normal and osteoporotic populations, age-adjusted multiple regression models based on IGF-I, IGF-II, IGFBP-3, and IGFBP-5 were found to be highly predictive of serum OC (R2 = 19%, p < 0.001) and BMD of femoral neck (R2 = 49%, p < 0.0001), consistent with an effect of the anabolic IGF components on overall bone formation rate. Similar models based on 25(OH)D3 and PTH, however, were statistically unrelated to OC. To address further the potential impact of trauma on circulating IGF system components, we measured IGF system component levels in 10 male patients within 18 h following tibial fracture and in 10 age-matched normal male subjects. There was no significant difference in serum level of any of the IGF system components between the two groups. Although limited by its cross-sectional design, the present study suggests that, in addition to bone resorption resulting from secondary hyperparathyroidism, impaired bone formation associated with deficiency of the IGF system might predispose elderly women to fragility fracture of the proximal femur.

Endogenous hormones and the risk of hip and vertebral fractures among older women. Study of Osteoporotic Fractures Research Group

BACKGROUND AND METHODS

In postmenopausal women, the serum concentrations of endogenous sex hormones and vitamin D might influence the risk of hip and vertebral fractures. In a study of a cohort of women 65 years of age or older, we compared the serum hormone concentrations at base line in 133 women who subsequently had hip fractures and 138 women who subsequently had vertebral fractures with those in randomly selected control women from the same cohort. Women who were taking estrogen were excluded. The results were adjusted for age and weight.

RESULTS

The women with undetectable serum estradiol concentrations (<5 pg per milliliter [18 pmol per liter]) had a relative risk of 2.5 for subsequent hip fracture (95 percent confidence interval, 1.4 to 4.6) and subsequent vertebral fracture (95 percent confidence interval, 1.4 to 4.2), as compared with the women with detectable serum estradiol concentrations. Serum concentrations of sex hormone-binding globulin that were 1.0 microg per deciliter (34.7 nmol per liter) or higher were associated with a relative risk of 2.0 for hip fracture (95 percent confidence interval, 1.1 to 3.9) and 2.3 for vertebral fracture (95 percent confidence interval, 1.2 to 4.4). Women with both undetectable serum estradiol concentrations and serum sex hormone-binding globulin concentrations of 1 microg per deciliter or more had a relative risk of 6.9 for hip fracture (95 percent confidence interval, 1.5 to 32.0) and 7.9 for vertebral fracture (95 percent confidence interval, 2.2 to 28.0). For those with low serum 1,25-dihydroxyvitamin D concentrations (< or =23 pg per milliliter [55 pmol per liter]), the risk of hip fracture increased by a factor of 2.1 (95 percent confidence interval, 1.2 to 3.5).

CONCLUSIONS

Postmenopausal women with undetectable serum estradiol concentrations and high serum concentrations of sex hormone-binding globulin have an increased risk of hip and vertebral fracture.

Bilateral tibial marrow ablation in rats induces a rapid hypercalcemia arising from extratibial bone resorption inhibitable by methylprednisolone or deflazacort

The goals of this study were to quantitate biochemical markers of bone metabolism on days 1-15 after bilateral tibial marrow ablation surgery in young adult rats and to determine the effect of a single dose of methylprednisolone (2 mg/kg) or deflazacort (2.5 mg/kg) given at the time of ablation. Unexpectedly, serum calcium levels rose to a maximum of 15.9 mg/dl on day 7 after marrow ablation and remained above normal through day 15. This increase was blocked by a single intramedullary injection of methylprednisolone or deflazacort immediately following ablation; however, the fact that both drugs produced a characteristic rapid 3- to 10-fold increase in the serum alpha 2-macroglobulin level demonstrates that the drugs rapidly reached the circulation. Both methylprednisolone and deflazacort also inhibited intramedullary deposition of collagen by 40-60% on day 7, a time near which operated control animals achieved maximal accumulation of new bone in this model. Histological comparisons among the three experimental groups were largely consistent with biochemical results. The urinary hydroxyproline/creatine ratio for the operated control group doubled on day 3 and then returned to presurgical levels on day 7 and later. The timing and size of the hydroxyproline/creatinine peak, as well as the fact that the intratibial osteoclastic response peaks on days 8-10 after ablation, suggests it results from extratibial bone resorption induced by marrow ablation. Consistent with this rationale, urinary calcium excretion in operated controls rose 9-fold from day 0 to day 3 and appeared to plateau over the period from day 3 to day 9, before returning to a near presurgical level on day 15. Elevated excretion of calcium noted on days 9-15 in deflazacort-treated animals, which occurs in the absence of a detectable increase in resorption marker hydroxyproline, may however be due to the known action of glucocorticoids in increasing kidney filtration of calcium. In summary, this is the first report to show that bilateral tibial marrow ablation in rats causes a rapid hypercalcemia and calciuria which is accompanied initially by a peak of bone resorption marker urinary hydroxyproline. We speculate that the source of calcium and hydroxyproline is extratibial osteoclastic bone resorption induced by circulating cytokines whose release from ablated tibias or osteoclastogenic action is inhibitable by methylprednisolone and deflazacort.

Lack of in vitro evidence for storage of 1,25-dihydroxycholecalciferol (1,25(OH)2D3) and 1,25(OH)2D3 binding protein in skeletal matrix

A few studies have reported on the measurement of 1, 25-dihydroxycholecalciferol (1,25(OH)2D3) in bone, using chloroform/methanol extraction and radioreceptor assay. As the significance of bone 1,25(OH)2D3 content was not defined in any of these reports, the objective of the current investigation was to determine whether 1,25(OH)2D3 may be stored in skeletal matrix. Bone powder samples from the iliac crest were extracted in ethylacetate/cyclohexane and 1,25(OH)2D3 isolated from the extract by means of Sephadex LH-20 and high pressure liquid chromatographic separation and subsequently measured by radioimmunoassay (RIA). Within the detection range of the RIA, no 1,25(OH)2D3 could be measured, suggesting that 1,25(OH)2D3 is not stored in skeletal matrix. Vitamin D bone concentrations previously measured may therefore have reflected plasma contamination. Consistent with this hypothesis, only traces of skeletal 1,25(OH)2D3 binding protein were measured when compared with serum values. Although 1,25(OH)2D3 may act as a potential local determinant of bone remodeling, there is no evidence supporting a delayed paracrine function by matrix-derived 1, 25(OH)2D3.

Age-related bone loss and senile osteoporosis: evidence for both secondary hyperparathyroidism and skeletal growth factor deficiency in the elderly

Aging is characterized by a decrease in bone volume, implying that net bone resorption exceeds net bone formation. This age-related bone loss can be regarded as the main determinant of hip fracture risk in the elderly. In the concept of senile osteoporosis, a key role has been attributed to vitamin D deficiency. Lack of vitamin D activity may affect femoral strength through impaired mineralization as well as through a hyperparathyroidism-mediated increase in bone resorption. In addition to vitamin D-related mechanisms, recent evidence has indicated a decline in the skeletal content of anabolic growth factors--such as insulin-like growth factor-I (IGF-I)--in femoral (cortical) bone, suggesting that skeletal growth factor deficiency may contribute to the age-related bone loss in the proximal femur as well. It is tempting to speculate that skeletal IGF-I loss might, at least partially, be accounted for by growth hormone deficiency. However, critical evidence does not yet support the concept that the decreased activity of the growth hormone-IGF-I-axis alters bone remodeling, and the extent to which serum concentrations of growth factors are reflective of skeletal activity remains to be clarified.

Increased bone resorption and decreased bone formation in Chinese patients with hip fracture

Biochemical markers of bone formation (bone-specific alkaline phosphatase and osteocalcin) and bone resorption (hydroxyproline excretion and bone isoenzyme of acid phosphatase) were measured in 30 patients (15 M and 15 F) with hip fracture and 30 healthy subjects matched for age and sex. Bone isoenzyme of tartrate-resistant acid phosphatase (TRACP) was measured by a recently developed specific immunoassay. Serum osteocalcin concentration and bone-specific alkaline phosphatase activity were significantly lower and serum TRACP concentration and urinary hydroxyproline excretion were elevated in patients compared with healthy subjects. We suggest that there is reduced bone formation and increased bone resorption in patients with hip fracture.

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)

Serum osteocalcin and fracture susceptibility in elderly women

The purpose of this investigation was to evaluate the bone turnover by using bone metabolic markers in relation to previous fracture history and independent of bone mass. Patients and controls were recruited from a population-based study of 193 women, all living in the same city and aged 60, 70, and 80 years. The bone mineral content (BMC) was measured bilaterally in the distal forearm by single-photon absorptiometry (SPA). At the same time, serum samples were obtained for biochemical analysis. Of the 193 women, we identified 26 with at least one major fracture during the past few years. Each of these 26 women with a certified recent previous fracture was individually matched with a woman from the same study group of equal BMC and age but without a fracture history. In the two groups, the serum samples were analyzed for osteocalcin, C-terminal procollagen peptide (P1CP), alkaline phosphatase, bone-specific alkaline phosphatase, calcium, phosphate, and albumin. The serum concentration of osteocalcin was 20% lower in the women with a previous fracture than in the controls (P = 0.03). The other markers of bone formation gave similar values in the two groups. There was a significant correlation between the osteocalcin and P1CP concentrations (P = 0.001). Our findings indicate that the susceptibility to fractures independent of factors such as age and BMC may be related to a decreased bone turnover.

Biochemical markers of nutrition in osteoporosis

Thirty-six women with vertebral osteoporosis showed significantly decreased levels of biochemical markers of nutrition, transferrin (P < 0.001), prealbumin (P < 0.001), retinol binding-protein (P < 0.001), and fibronectin (P < 0.001), compared with 40 healthy women of similar age. Multiple regression analysis showed a significant (R2 = 0.509; P = 0.0068) correlation between bone mineral content and biochemical markers of nutrition in the osteoporotic patients but not in the control group. These data suggest that postmenopausal osteoporosis may be associated with a nutritional deficiency.

Serum intact parathyroid hormone levels in elderly Chinese females with hip fracture

Serum intact parathyroid hormone (PTH), 25 hydroxyvitamin D(25OHD), 1,25 dihydroxyvitamin D (1,25(OH)2D), albumin, and ionized calcium were measured in 61 Chinese female patients with hip fracture and 61 control subjects. Hip fracture patients had low albumin, ionized calcium, and 250HD levels. Serum PTH and 1,25(OH)2D values were not different between the two groups. We conclude that although 250HD level in hip fracture patients is low, there is no evidence of secondary hyperparathyroidism, suggesting that the low 250HD levels may be a secondary phenomenon in response to the fracture.

Crush fracture syndrome in senile osteoporosis: a nutritional consequence?

Osteoporosis is a very important age-related health problem. The body's composition changes with age, and these changes are a true reflection of aging and of the individuals's nutritional status. Mineral content changes have been reported in vertebral osteoporosis. Interestingly, enough, there have not been reports on concomitant water, fat, and fat-free mass changes associated with this condition. In this report, changes in the latter parameters are compared between patients with osteoporosis and controls. The four components (water, mineral, fat, and fat-free mass) were found significantly reduced (p less than 0.001) in osteoporosis. Serum albumin and protein mass were also reduced (p less than 0.001).

Preferential low bone mineral density of the femoral neck in patients with a recent fracture of the proximal femur

Bone mass is an important determinant of resistance to fractures. Whether bone mineral density (BMD) in subjects with a fracture of the proximal femur (hip fracture) is different from that of age-matched controls is still debated. We measured BMD of the femoral neck (FN) on the opposite side to the fracture, as well as femoral shaft (FS) and lumbar spine (LS) BMD by dual-photon absorptiometry in 68 patients (57 women and 11 men, mean age 78.8 +/- 1.0) 12.4 +/- 0.8 days after hip fracture following a moderate trauma. These values were compared with BMD of 93 non-fractured elderly control subjects (82 women and 11 men), measured during the same period. As compared with the controls, FN BMD was significantly lower in fractured women (0.592 +/- 0.013 v. 0.728 +/- 0.014 g/cm2, P less than 0.001) and in fractured men (0.697 +/- 0.029 v. 0.840 +/- 0.052, P less than 0.05). Expressed as standard deviations above or below the mean BMD of age and sex-matched normal subjects (Z-score), the difference in FN BMD between fractured women and controls was highly significant (-0.6 +/- 0.1 v. +0.1 +/- 0.1, P less than 0.001). As compared with mean BMD of young normal subjects, BMD was decreased by 36.9 +/- 1.4 and 22.4 +/- 1.5% (P less than 0.001) in fractured and control women, respectively. There was no significant difference between FN BMD of 33 women with cervical and 24 with trochanteric hip fractures (0.603 +/- 0.017 v. 0.577 +/- 0.020). FN BMD was lower than 0.705 g/cm2 in 90% of fractured women.(ABSTRACT TRUNCATED AT 250 WORDS)

Osteocalcin: diagnostic methods and clinical applications

Osteocalcin is a small (Mr 5800), very interesting bone specific protein, synthesized by osteoblasts and measured in plasma as a biochemical indicator of bone formation. Many immunoassays for osteocalcin have been developed, including radio- and enzymoimmunoassays, with the use of monoclonal and polyclonal antibodies. These are used in many different clinical settings, including bone, kidney, and liver diseases. However, there is a wide range of published values for plasma osteocalcin concentrations in control and patient samples and this has hindered a more widespread adoption of osteocalcin measurement by clinicians. This review discusses how various immunoassays for osteocalcin may contribute to the wide variation of published values and suggests approaches for the development of standardized assays. For example, epitope specificity and immunoreactivity with multiple forms of osteocalcin and osteocalcin peptides in plasma are discussed. It also includes a recent update on interesting clinical applications of osteocalcin.