Alcohol Consumption Moderated the Association Between Levels of High Blood Lead or Total Urinary Arsenic and Bone Loss

Metal exposure and lifestyle are important risk factors for osteoporosis. Our study aimed to investigate the association between red blood cell lead and cadmium, total urinary arsenic, and plasma selenium levels and bone mineral density (BMD). In addition, we explored whether alcohol and coffee consumption modified the association between BMD and metals and metalloids. In total, 437 participants who underwent adult or senile physical examinations were recruited. Bone loss was defined as a calcaneus BMD T-score of <-1. Blood cadmium and lead and plasma selenium levels were measured using inductively coupled plasma mass spectrometry. Levels of urinary arsenic species were determined using high-performance liquid chromatography-hydride generator-atomic absorption spectrometry. The total urinary arsenic level was defined as the sum of the levels of urinary arsenic species. The BMD T-scores decreased significantly with increasing blood lead levels. The BMD T-scores also showed a downward trend with increasing total urinary arsenic levels. The odds ratio (OR) and 95% confidence interval (CI) for bone loss in patients with blood lead levels >57.58 versus 35.74 μg/dL were 1.98 and 1.17-3.34. In addition, the greater the lead or arsenic exposure and alcohol intake was the higher the OR for bone loss with multivariate ORs of 2.57 (95% CI 1.45-4.56) and 2.96 (95% CI 1.67-5.22), respectively. To the best of our knowledge, this study is the first to demonstrate that high total urinary arsenic or blood lead levels and frequent or occasional alcohol consumption had a significant multiplicative interaction for increasing the OR for bone loss.

Use of calcimimetics in children with normal kidney function

The calcium-sensing receptor (CaSR) plays an important role in the homeostasis of serum ionized calcium by regulating parathyroid hormone (PTH) secretion and tubular calcium handling. Calcimimetics, which act by allosteric modulation of the CaSR, mimic hypercalcemia resulting in suppression of PTH release and increase in calciuria. Mostly used in children to treat secondary hyperparathyroidism associated with advanced renal failure, we have shown that calcimimetics can also be successfully used in children with bone and mineral disorders in which elevated PTH plays a detrimental role in skeletal pathophysiology in the face of normal kidney function. The current review briefly discusses the role of the CaSR and calcimimetics in calcium homeostasis, and then addresses the potential applications of calcimimetics in children with normal kidney function with disorders in which suppression of PTH is beneficial.

Association of Dietary Carotenoids Intake with Skeletal Fluorosis in the Coal-burning Fluorosis Area of Guizhou Province

OBJECTIVE

To explore whether the intake of dietary carotenoids could protect against skeletal fluorosis in Guizhou province in which coal-burning fluorosis is endemic.

METHODS

A case-control study of 196 patients with skeletal fluorosis and 196 age and gender-matched controls was conducted in Zhijin, Guizhou Province. Face-to-face interviews were conducted to assess habitual dietary intake using a 75-item food frequency questionnaire and various covariates with structured questionnaires. Urinary fluoride was measured using an ion-selective electrode method. The genotype of superoxide dismutase 2 (SOD2) rs11968525 was detected by TaqMan method.

RESULTS

We observed significant dose-dependent inverse associations of skeletal fluorosis with intake of β-carotene, lutein/zeaxanthin, lycopene, and total carotenoids (P-trend = 0.002 to 0.018), whereas α-carotene and β-cryptoxanthin intakes were not found to be related to skeletal fluorosis, after adjustment for potential confounders. The adjusted ORs and 95% CI of skeletal fluorosis for the highest versus lowest quartile were 0.30 (0.10, 0.86) for β-carotene, 0.23 (0.08, 0.66) for lycopene, 0.26 (0.10, 0.75) for lutein/zeaxanthin and 0.34 (0.14, 0.74) for total carotenoids (all P-trend < 0.05). Stratified analyses showed that the protective effects of lutein/zeaxanthin and total carotenoids on skeletal fluorosis were more evident for individuals with the AG+AA genotypes of SOD2 (rs11968525).

CONCLUSION

Increased intakes of β-carotene, lutein/zeaxanthin, lycopene, and total carotenoids are independently associated with a lower risk of coal-burning skeletal fluorosis. SOD2 (rs11968525) polymorphisms might modify the inverse associations between dietary carotenoids and skeletal fluorosis.

FRZB1 rs2242070 polymorphisms is associated with brick tea type skeletal fluorosis in Kazakhs, but not in Tibetans, China

Skeletal fluorosis is a metabolic bone and joint disease caused by excessive accumulation of fluoride in the bones. Compared with Kazakhs, Tibetans are more likely to develop moderate and severe brick tea type skeletal fluorosis, although they have similar fluoride exposure. Single nucleotide polymorphisms (SNPs) in frizzled-related protein (FRZB) have been associated with osteoarthritis, but their association with the risk of skeletal fluorosis has not been reported. In this paper, we investigated the association of three SNPs (rs7775, rs2242070 and rs9288087) in FRZB1with brick tea type skeletal fluorosis risk in a cross-sectional case-control study conducted in Sinkiang and Qinghai, China. A total of 598 individuals, including 308 Tibetans and 290 Kazakhs, were enrolled in this study, in which cases and controls were 221 and 377, respectively. The skeletal fluorosis was diagnosed according to the Chinese diagnostic criteria of endemic skeletal fluorosis (WS192-2008). The fluoride content in tea water or urine was detected using the fluoride ion electrode. SNPs were assessed using the Sequenom MassARRAY system. Binary logistic regressions found evidence of association with rs2242070 AA genotype in only Kazakh participants [odds ratio (OR) 0.417, 95% CI 0.216-0.807, p = 0.009], but not in Tibetans. When stratified by age, this protective effect of AA genotype in rs2242070 was pronounced in Kazakh participants aged 46-65 (OR 0.321, 95% CI 0.135-0.764, p = 0.010). This protective association with AA genotype in rs2242070 in Kazakhs also appeared to be stronger with tea fluoride intake > 3.5 mg/day (OR 0.396, 95% CI 0.182-0.864, p = 0.020). Our data suggest there might be differential genetic influence on skeletal fluorosis risk in Kazakh and Tibetan participants and that this difference might be modified by tea fluoride intake.

Acid retention with reduced glomerular filtration rate increases urine biomarkers of kidney and bone injury

Diets high in acid of developed societies that do not cause metabolic acidosis in patients with chronic kidney disease nevertheless appear to cause acid retention with associated morbidity, particularly in those with reduced glomerular filtration rate. Here we used a rat 2/3 nephrectomy model of chronic kidney disease to study induction and maintenance of acid retention and its consequences on indicators of kidney and bone injury. Dietary acid was increased in animals eating base-producing soy protein with acid-producing casein and in casein-eating animals with added ammonium chloride. Using microdialysis to measure the kidney cortical acid content, we found that nephrectomized animals had greater acid retention than sham-operated animals when both ate the soy diet. Each increment in dietary acid further increased acid retention more in nephrectomized than in sham rats. Nephrectomized and sham animals achieved similar steady-state daily urine net acid excretion in response to increments in dietary acid but nephrectomized animals took longer to do so, contributing to greater acid retention that was maintained until the increased dietary acid was stopped. Acid retention was associated with increased urine excretion of both N-acetyl-β-D-glucosaminidase and deoxypyridinoline, greater in nephrectomized than control rats, consistent with kidney tubulointerstitial and bone matrix injury, respectively. Greater acid retention in nephrectomized than control animals was induced by a slower increase in urinary net acid excretion rate in response to the increment in dietary acid and also maintained until the dietary acid increment was stopped. Thus, acid retention increased biomarkers of kidney and bone injury in the urine, supporting untoward consequences to these two tissues.

Association between urinary lead and bone health in a general population from Taiwan

Lead accumulates in adult bones for many decades; previous studies have shown lead's detrimental effects on osteoblast and osteoclast activity in association with bone remodeling. Osteoporosis is a disease of the bones resulting in low bone mass that induces fragile bones and hence susceptibility of fracture. We estimated the association between urinary lead (U-Pb) levels and bone health in adults participating in the third Nutrition and Health Survey in Taiwan (NAHSIT) from 2005 to 2008. A total of 398 participants were divided into normal (T-score>-1), osteopenic (T-score between -1 and -2.5), or osteoporotic (T-score<-2.5) groups according to the results of bone mineral density (BMD) measurements. Heavy metals were measured in urine specimens using inductively coupled plasma-mass spectrometry. In the multivariable logistic regression analysis, age (OR=1.08; 95% CI=1.05-1.10), former smokers (OR=2.95; 95% CI=1.22-7.11) and higher U-Pb levels than upper tertile (OR=2.30; 95% CI=1.19-4.48) were associated with osteopenia/osteoporosis. Furthermore, age (OR=1.06; 95% CI=1.02-1.10) and higher U-Pb levels (OR=2.81; 95% CI=1.13-6.97) were significantly associated with osteopenia and osteoporosis in women. These results suggest that adults, particularly in women, with higher U-Pb levels may have increased odds of osteopenia and osteoporosis.

The protective effect of lycopene intake on bone loss in ovariectomized rats

Antioxidant lycopene supplementation has been shown to decrease oxidative stress and have beneficial effects on bone health. However, it remains unclear whether lycopene exerts its beneficial effect on bone metabolism through mitigation of oxidative stress in vivo. The aim of this study was to investigate whether lycopene intake protects against bone loss by reducing oxidative stress in ovariectomized rats. Female Sprague-Dawley 6-week-old rats were ovariectomized and randomly divided into four groups according to the lycopene content of their diet: 0, 50, 100, and 200 ppm. The tibial bone mineral density (BMD) in the 50, 100, and 200 ppm groups was significantly higher than that in the 0 ppm group. Serum and urinary bone resorption marker levels were significantly lower in the 50, 100, and 200 ppm groups than in the 0 ppm group. There was no significant difference in systemic oxidative stress markers among all groups. However, systemic oxidative stress levels were inversely correlated with the tibial BMD. Our findings suggest that lycopene intake significantly inhibits bone loss by suppressing bone resorption in ovariectomized rats. Further studies are necessary to clarify the effect of lycopene on oxidative stress in local tissues such as bone tissue.

Evaluation of the anti-osteoporotic effects of metformin and sitagliptin in postmenopausal diabetic women

Osteoporosis is the most important metabolic bone disease in patients with diabetes mellitus. Several studies have documented that metformin is osteogenic in vitro. In contrast, others showed no effect of metformin on the osteogenic differentiation of bone marrow-derived mesenchymal stem cells. Incretin hormones have received much attention because of their beneficial effects beyond glycemia, including on bone health. The study evaluated the anti-osteoporotic effect of metformin and sitagliptin in postmenopausal diabetic women. Forty postmenopausal diabetic women were randomly divided into two equal groups. Group 1 received metformin (Glucophage(®) 500 mg) 1 tablet twice daily, and group 2 received sitagliptin (Januvia(®) 100 mg) 1 tablet/day, for 12 weeks. Fasting blood and urine samples were collected for measurement of serum total alkaline phosphatase (ALP), osteocalcin, and urinary deoxypyridinoline (DPD). Laboratory tests were measured at baseline, after 4 and 8 weeks, and at the end of the study. Bone mineral density of the anterior posterior lumbar spine was measured by dual energy X-ray absorptiometry at baseline and after 12 weeks of the intervention. In the metformin-treated group, the mean values for all markers of bone turnover at 12 weeks of treatment were not significantly different from baseline. In group 2, the mean serum total ALP was significantly decreased, serum osteocalcin levels were non-significantly decreased gradually by 10% at 12 weeks, while urinary DPD decreased significantly and was then maintained at 28% decrease at 12 weeks. In conclusion, metformin is neither osteogenic nor has anti-osteoporotic effect, while sitagliptin could positively regulate bone metabolism.

The relationship between fibroblast growth factor 23 and osteoporosis in postmenopausal women

AIM

A lack of estrogen in postmenopausal women is an important factor causing the development of osteoporosis. Our purpose is to investigate the effects of Fibroblast Growth Factor 23 (FGF-23) on bone mineral metabolism and bone turnover.

METHODS

Twenty-eight patients with postmenopausal osteoporosis (PMO), 32 patients with postmenopausal osteopenia and 30 healthy control subjects (postmenopausal non-osteoporosis) were included in this study. In order to assess the bone mineral metabolism; FGF 23, parathyroid hormone, vitamin D, calcium, phosphate, osteocalcin, alkaline phosphatase and hydroxyproline levels were measured.

RESULTS

FGF 23 levels were found significantly higher in PMO group compared with postmenopausal osteopenia and control groups (P<0.01 and P<0.05 respectively). Urine hydroxyproline level was detected to be significantly lower in PMO patients compared with control group (P<0.01). Lomber and femur BMD levels were found to be significantly lower in PMO patients compared with postmenopausal osteopenia and control groups (P<0.001, P<0.001; P<0.001, P<0.001 respectively). On the other hand, when we categorized the PMO group subjects according to the age of menopause, the FGF 23 levels were found to be significantly higher in the group of menopausal age <5 years compared to the group of menopausal age >10 and to the group of menopausal age 5-10 years (P<0.05, P<0.05).

CONCLUSION

We think our findings indicate that serum FGF 23 level is a significant determinant of increased bone turnover at early periods in PMO patients.

Mitigation of oxidative damage by green tea polyphenols and Tai Chi exercise in postmenopausal women with osteopenia

BACKGROUND

Osteoporosis is a degenerative bone disease predominantly in postmenopausal women. Green tea polyphenols (GTP) and Tai Chi (TC) have been shown to be beneficial on human bone health. This study examined the efficacy of GTP and TC on mitigation of oxidative damage in postmenopausal women with osteopenia.

METHODS

A 6-month randomized and placebo-controlled clinical trial was conducted in 171 postmenopausal women with osteopenia, who were recruited from Lubbock County, Texas. These participants were treated with placebo, GTP (500 mg daily), placebo + TC (60-minute group exercise, 3 times/week), or GTP (500 mg daily) + TC (60-minute group exercise, 3 times/week), respectively. Their blood and urine samples were collected at the baseline, 1-, 3- and 6-months during intervention for assessing levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG), an oxidative DNA damage biomarker, and concentrations of serum and urine GTP components.

RESULTS

The elevated concentrations of serum and urinary GTP components demonstrated a good adherence for the trial. A significant reduction of urinary 8-OHdG concentrations was found in all three treated groups during 3-month (P<0.001) and 6-month (P<0.001) intervention, as compared to the placebo group. The significant time- and dose-effects on mitigation of the oxidative damage biomarker were also found for GTP, TC, and GTP+TC intervened groups.

CONCLUSION

Our study demonstrated that GTP and TC interventions were effective strategies of reducing the levels of oxidative stress, a putative mechanism for osteoporosis in postmenopausal women, and more importantly, working in an additive manner, which holds the potential as alternative tools to improve bone health in this population.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00625391.

The validity of biochemical markers in metabolic bone disease in preterm infants: a systematic review

To establish the validity of biochemical markers of metabolic bone disease (MBD) in preterm infants.

CONCLUSION

There is insufficient evidence that any of the frequently used serum measurements are valid biochemical markers of MBD in preterm infants. Increased urinary calcium concentration may be a valid biochemical marker, but more research is necessary to confirm this.

Urinary cadmium, osteopenia, and osteoporosis in the US population

SUMMARY

The association between cadmium and osteoporosis in a multiethnic population is unclear. We found that urinary cadmium is consistently associated with osteopenia and osteoporosis in the Third National Health and Nutrition Examination Survey, regardless of age, sex, race, and smoking status. Cadmium exposure may be an independent risk factor for osteoporosis.

INTRODUCTION

Our purpose was to test whether cadmium exposure is associated with a higher prevalence of osteopenia and osteoporosis in the general US population and selected subgroups.

METHODS

We used multinomial logistic regression to analyze data on 10,978 subjects (aged 30-90) from the Third National Health and Nutrition Examination Survey. We studied the association of urinary cadmium levels (adjusted for urinary creatinine) and the prevalence of osteopenia and osteoporosis as defined by the World Health Organization.

RESULTS

After adjustment for age, sex, ethnicity, body mass index, calcium intake, and physical inactivity, odds ratios (ORs) for osteopenia and osteoporosis increased dose dependently with two urinary cadmium levels (in micrograms of urinary cadmium per grams of urinary creatinine: level I, 1.00-1.99 mcg/g; level II, > or =2.00 mcg/g). Osteopenia results were as follows: level I OR, 1.49 (95% confidence interval [CI], 1.24-1.80); level II OR, 2.05 (95% CI, 1.52-2.78). Osteoporosis results were as follows: level I OR, 1.78 (95% CI, 1.26-2.52); level II OR, 3.80 (95% CI, 2.36-6.14). The association was consistent in all age, sex, race, and smoking status subgroups.

CONCLUSIONS

Cadmium exposure may be a potential risk factor for osteopenia and osteoporosis in the general US population.

Assessment of adherence to treatment of postmenopausal osteoporosis with raloxifene and/or alfacalcidol in postmenopausal Japanese women

Patients who are diagnosed with osteoporosis and beginning treatment often discontinue their osteoporosis medication relatively early after the start of treatment because of their poor recognition of fracture risk and the asymptomatic nature of osteoporosis. In this study we aimed to assess adherence to treatment with 1 microg alfacalcidol (D), 60 mg raloxifene (R) or a combination of both (D + R) for 1 year in postmenopausal Japanese women with osteoporosis or osteopenia. We defined persistence of D and R as continuing to take tablets for more than 7 of any 14 days immediately before the 1-year visit. A total of 137 subjects aged 49-81 years [64.9 +/- 7.0 years, 16.0 +/- 12.7 years since menopause (YSM)] were randomly assigned to each treatment group. The proportions persisting with each treatment group at 1 year were 61.4, 65.3, 55.1% for D, R and D + R groups, respectively whereas the compliance to each therapy as judged by the medical possession ratio (MPR) at 1 year were 77.5, 93.8, 78.4%, respectively. There were no significant differences in persistence, compliance and the number of subjects who discontinued treatment due to adverse events among each group. We found significant inverse correlations in percent changes at 1 year between compliance and serum BAP in R and D + R groups or urinary (u-) CTX in the R group. The changes in the level of serum BAP and u-CTX were significantly higher in high-compliance patients (MPR > 80%) treated with raloxifene alone or concomitantly with alfacalcidol compared to those in low-compliance patients.

Bone metabolic disorder in patients with prostate cancer receiving androgen deprivation therapy (ADT): impact of ADT on the growth hormone/insulin-like growth factor-1/parathyroid hormone axis

BACKGROUND

Although androgen deprivation therapy (ADT) has been associated with bone loss in patients with prostate cancer, its mechanism remains unclear. The growth hormone (GH)/insulin-like growth factor-1 (IGF-1)/parathyroid hormone (PTH) axis plays a critical role in bone synthesis, but its activity during ADT is also unknown.

METHODS

Seventy-one patients with localized prostate cancer, who received ADT, were prospectively studied based on their bone mineral density (BMD) and blood and urine samples at the baseline and after ADT for 6 months.

RESULTS

The IGF-1 level was correlated with BMD before ADT (rs = 0.325, P = 0.007), but such a relationship disappeared after ADT (P = 0.565). Following ADT, the serum IGF-1 level increased compared with that at the baseline (22 +/- 6 nmol/L vs. 19 +/- 5 nmol/L, respectively, P < 0.001). The serum PTH level was reduced after ADT (41 +/- 33 ng/L) compared with the baseline (55 +/- 44 ng/L) (P < 0.001), but no change was observed in the serum GH level (P = 0.691). Bone resorption markers such as blood N-telopeptide (NTx), urinary NTx, calcium, and inorganic phosphorus levels increased after ADT (P < 0.001 in all). The ratio of the IGF-1 level after ADT/before ADT was associated with the ratio of the value after ADT/before ADT of alkaline phosphatase (rs = 0.266, P = 0.025) and calcium (rs = 0.242, P = 0.042).

CONCLUSION

Despite the unaffected GH and upregulated bone resorption, the serum IGF-1 level was elevated by ADT. The IGF-1 level was correlated with BMD before ADT, but the relationship was disrupted after ADT. IGF-1 or its receptor in the bone may be functionally inactivated during ADT.

HLA-B27 rats develop osteopaenia through increased bone resorption without any change in bone formation

Osteopaenia is a common complication of inflammatory bowel diseases (IBD). However, the mechanisms of bone loss are still the subject of debate. The aims of this study were to investigate bone loss in HLA-B27 transgenic rats, a spontaneous model of colitis and to compare the results provided by the usual markers of bone remodelling and by direct measurement of bone protein synthesis. Systemic inflammation was evaluated in HLA-B27 rats and control rats from 18 to 27 months of age. Then bone mineral density, femoral failure load, biochemical markers of bone remodelling and protein synthesis in tibial epiphysis were measured. Bone mineral density was lower in HLA-B27 rats than in controls. Plasma osteocalcin, a marker of bone formation, and fractional protein synthesis rate in tibial epiphysis did not differ between the two groups of rats. In contrast, urinary excretion of deoxypyridinoline, a marker of bone resorption, was significantly increased in HLA-B27 rats. The present results indicate that bone fragility occurs in HLA-B27 rats and mainly results from an increase in bone resorption. Systemic inflammation may be the major cause of the disruption in bone remodelling homeostasis observed in this experimental model of human IBD.

[Vitamin status and bone mineral density at patients with diseases of gastroenteric tract]

It has been shown that among patients suffering from diseases of a gastroenteric tract and osteopenia the calcium insufficiency estimated on daily calcium urinary excretion and the lowered level of the transport form of vitamin D in blood serum take place more often, than among patients with the same pathologies, but without osteopenia. The most significant risk factors of bone mass decrease at the patients who have transferred operations on organs of digestion are insufficient supply with calcium and vitamin D and the body weight loss.

Clinical application of biochemical markers of bone turnover

With the ageing population in most countries, disorders of bone and mineral metabolism are becoming increasingly relevant to every day clinical practice. Consequently, the interest in, and the need for effective measures to be used in the screening, diagnosis and follow-up of such pathologies have markedly grown. Together with clinical and imaging techniques, biochemical tests play an important role in the assessment and differential diagnosis of metabolic bone disease. In recent years, the isolation and characterisation of cellular and extracellular components of the skeletal matrix have resulted in the development of molecular markers that are considered to reflect either bone formation or bone resorption. These biochemical indices are non-invasive, comparatively inexpensive and, when applied and interpreted correctly, helpful tools in the diagnostic and therapeutic assessment of metabolic bone disease. This review provides an overview of the current evidence regarding the clinical use of biochemical markers of bone remodelling in bone disease, with an emphasis on osteoporosis.

An update on biomarkers of bone turnover and their utility in biomedical research and clinical practice

BACKGROUND

Maintenance of the structural and functional integrity of the skeleton is a critical function of a continuous remodeling driven by highly associated processes of bone resorption and synthetic activities driven by osteoclasts and osteoblasts, respectively. Acceleration of bone turnover, accompanied with a disruption of the coupling between these cellular activities, plays an established role in the pathogenesis of metabolic bone diseases, such as osteoporosis. During the past decades, major efforts have been dedicated to the development and clinical assessment of biochemical markers that can reflect the rate of bone turnover. Numerous studies have provided evidence that serum levels or urinary excretion of these biomarkers correlate with the rate of bone loss and fracture risk, proving them as useful tools for improving identification of high-risk patients.

OBJECTIVE

The aim of the present review is to give an update on biomarkers of bone turnover and give an overview of their applications in epidemiological and clinical research.

DISCUSSION

Special attention is given to their utility in clinical trials testing the efficacy of drugs for the treatment of osteoporosis and how they supplement bone mass measurements. Recent evidence suggests that biochemical markers may provide information on bone age that may have indirectly relates to bone quality; the latter is receiving increasing attention. A more targeted use of biomarkers could further optimize identification of high-risk patients, the process of drug discovery, and monitoring of the efficacy of osteoporosis treatment in clinical settings.

Effect of vitamin K2 treatment on carboxylation of osteocalcin in early postmenopausal women

OBJECTIVE

We examined the serum level of undercarboxylated osteocalcin (uc OC), which is a sensitive marker of vitamin K status, and levels of bone turnover markers in early postmenopausal women receiving vitamin K2 treatment with or without vitamin D3.

METHODS

Thirty-four postmenopausal women with a mean age of 53 years whose bone mineral density (BMD) was less than 0.809 g/cm2 (osteopenia and osteoporosis) were treated with vitamin K2 or with a combination of vitamin K2 and vitamin D3. Seventeen women received daily oral administration of 45 mg vitamin K2 and 17 women received daily oral administration of 45 mg vitamin K2 plus 0.75 microg 1alpha-hydroxyvitamin D3. Serum levels of uc OC, intact osteocalcin (OC) and bone alkaline phosphatase (BAP), urinary deoxypyridinoline (DPD) levels and BMD at the lumbar spine were measured before and at 1 and 2 years after the start of treatment.

RESULTS

Serum uc OC levels in women treated with vitamin K2 alone and with both vitamin K2 and vitamin D3 decreased significantly (p < 0.05). Serum levels of intact OC and BAP in women treated with vitamin K2 did not show significant changes, while those in women who received the combined treatment decreased significantly (p < 0.05). On the other hand, urinary DPD level in women treated with vitamin K2 did not change, while that in women who received the combined treatment tended to decrease (p < 0.1).

CONCLUSION

Serum uc OC levels in early postmenopausal women who received vitamin K2 decreased due to carboxylation of uc OC. Combined treatment with vitamin K2 and vitamin D3 may be effective for sustaining BMD in early postmenopausal women whose bone turnovers are highly activated.

Altered levels of biochemical indices of bone turnover and bone-related vitamins in patients with Crohn's disease and ulcerative colitis

BACKGROUND

The pathogenesis of inflammatory bowel disease-associated osteopenia may be related to pathological rates of bone turnover; however, the literature shows mixed results.

AIM

To compare bone biomarkers in inflammatory bowel disease patients (Crohn's disease: n = 68, and ulcerative colitis: n = 32, separately) with age- and sex-matched healthy controls.

SUBJECTS

Patients and controls were recruited from Cork University Hospital and Cork City area, respectively.

RESULTS

Relative to that in their respective controls, Crohn's disease (n = 47) and ulcerative colitis (n = 26) patients (i.e. excluding supplement users) had significantly (P < 0.05-0.001) higher serum undercarboxylated osteocalcin (by 27% and 63%, respectively) and bone-specific alkaline phosphatase (by 15% and 21%, respectively) and urinary Type I collagen cross-linked N-telopeptides concentrations (by 87% and 112%, respectively). Relative to that in their respective controls, Crohn's disease and ulcerative colitis patients had significantly (P < 0.01) lower serum total osteocalcin (by 20% and 42%, respectively) and 25-hydroxyvitamin D (by 37% and 42%, respectively), while serum parathyroid hormone levels were similar. In the combined patient group (n = 100), undercarboxylated osteocalcin was positively associated with bone markers.

CONCLUSIONS

Both Crohn's disease and ulcerative colitis patients have altered bone turnover relative to that in healthy controls.

Insulin-like growth factor-I and mineral metabolism markers in children with idiopathic decrease in bone mass

OBJECTIVE

The aim of the study was to determine whether the serum concentration of insulin-like growth factor-I (IGF-I) and its binding protein-3 (IGFBP-3) correlates with the mineral metabolism markers in children with idiopathic decrease in bone mass.

PATIENTS AND METHODS

The study comprised 62 patients aged 6-18 years, including 42 with idiopathic decrease in bone mineral density (20 with osteoporosis and 22 with osteopenia) and 20 control children. Osteoporosis and osteopenia were diagnosed on the basis of complex clinical, densitometric and biochemical examinations (in all patients secondary causes of the decreased bone mass were excluded). Serum concentration of IGF-I was determined with radioimmunoassay and IGFBP-3 using immunoradiometry.

RESULTS

The children with osteoporosis and osteopenia were found to have mean IGF-I concentration statistically significantly lower than the controls (548 and 645 v. 819 ng/ml, respectively; p<0.05). Moreover, IGF-I correlated positively with total and spinal bone mineral density. In children with osteoporosis there was also a significant relationship between IGF-I and pyridinoline and deoxypyridinoline in urine.

CONCLUSIONS

Lower serum IGF-I concentration together with higher bone resorption and low bone mineral density reveal involvement of this growth factor in the development of idiopathic decrease of bone mass in children.

Reference values for urinary calcium and phosphorus to prevent osteopenia of prematurity

The prevention of osteopenia of prematurity is an important issue in the care of preterm infants. Fetal bone mineral accretion has been achieved in preterm infants by establishing and maintaining a simultaneous slight excretion of calcium (Ca) and phosphorus (P) (urine concentrations of 1-2 mmol/l) by means of an individual supplementation with Ca and/or P, resulting in a slight surplus supply (SSS). In this issue, Aladangady et al. present associations between urinary Ca/Cr and PO(4)/Cr ratios of preterm infants and biochemical variables of bone mineral metabolism. However, to date it has not been proven that these variables are a reliable substitute for direct measurement of bone mineral content (BMC). Before Ca/Cr and PO(4)/Cr ratios can be recommended as a new reference for improving BMC, the following steps are required: (1) direct measurement of BMC, (2) a prospective interventional trial to test and compare this new reference with the existing one (SSS, urinary Ca and P of 1-2 mmol/l) investigating BMC as primary outcome, and (3) adequate proof that Ca and P/Cr ratios are superior to simple urinary Ca and P concentrations.

Bones and Crohn's: risk factors associated with low bone mineral density in patients with Crohn's disease

Previous studies have confirmed that the prevalence of decreased bone mineral density is elevated in patients with inflammatory bowel disease. The objective of the current study was to determine the prevalence of osteopenia and osteoporosis in a cross-sectional outpatient population of 242 adult patients with Crohn's disease and to determine which clinical characteristics and serum and urine biochemical factors might be predictive of bone loss. Thirty-seven percent had normal bone density, 50.0% were osteopenic, and 12.9% were osteoporotic. Among the sites used to diagnose low bone mineral density, the femoral neck demonstrated the highest prevalence of osteopenia and the ultra-distal radius the highest prevalence of osteoporosis. However, low bone mineral density at one site was always predictive of low bone mineral density at the other. Corticosteroid use during the year before assessment was found to be consistently predictive of low bone mineral density in males but not in females. In contrast, low body mass index and high platelet counts were consistently predictive of low bone mineral density in females but not in males. Disease location, smoking, and age were not predictive of changes in bone mineral density.

Conditional estimation for generalized linear models when covariates are subject-specific parameters in a mixed model for longitudinal measurements

The relationship between a primary endpoint and features of longitudinal profiles of a continuous response is often of interest, and a relevant framework is that of a generalized linear model with covariates that are subject-specific random effects in a linear mixed model for the longitudinal measurements. Naive implementation by imputing subject-specific effects from individual regression fits yields biased inference, and several methods for reducing this bias have been proposed. These require a parametric (normality) assumption on the random effects, which may be unrealistic. Adapting a strategy of Stefanski and Carroll (1987, Biometrika74, 703-716), we propose estimators for the generalized linear model parameters that require no assumptions on the random effects and yield consistent inference regardless of the true distribution. The methods are illustrated via simulation and by application to a study of bone mineral density in women transitioning to menopause.

Urine products of bone breakdown as markers of bone resorption and clinical usefulness of urinary hydroxyproline: an overview

PURPOSE

The purpose of this study is to review the urine products of bone breakdown as markers of bone resorption and usefulness of urinary hydroxyproline.

DATA

Related researches published in 1985 - 2000 were systematically reviewed.

RESULTS

Bone markers could be used for early diagnosis of bone metabolic diseases. Biochemical markers of bone resorption that reflect osteoclast activity and/or collagen degradation provide a new and potentially important clinical tool for the assessment and monitoring of bone metabolism. Assessment of bone resorption can be achieved with measurement of urinary hydroxylysine glycosides, urinary excretion of the collagen pyridinium cross-links, urinary excretion of type I collagen telopeptide breakdown products (cross-linked telopeptides) and urinary hydroxyproline.

CONCLUSION

Urinary hydroxyproline has been in use as a marker of bone resorption, but it lacks sensitivity and specificity. It is a modified amino acid that is a metabolic product of collagen breakdown. Hydroxyproline may be released either free or with fragments of the collagen molecule attached during bone resorption, and it is also liberated by the breakdown of complement and nonskeletal collagen.

Alendronate reduces serum TNFalpha and IL-1beta, increases neutrophil counts, and improves bone mineral density and bone metabolism indices in patients with chronic idiopathic neutropenia (CIN)-associated osteopenia/osteoporosis

The current study was undertaken to investigate the effect of alendronate on bone mineral density (BMD), bone metabolism markers, and serum bone-resorbing cytokines in patients with chronic idiopathic neutropenia (CIN)-associated osteopenia/osteoporosis. Sixteen randomly selected women, 7 with CIN-associated osteoporosis and 9 with CIN-associated osteopenia, and 14 age- and menopausal status-matched healthy volunteers, were enrolled in the study. Patients received 10 mg alendronate daily per os for 360 days and studies were done before treatment (day 0) and at varying time points during the study. We found that patients' BMD measurements increased by 5.32% after treatment, and that the elevated serum osteocalcin (OC), a bone formation marker, decreased by day 30, normalized by day 90, and increased again by day 270 of treatment. Elevated values of patients' urine deoxypyridinoline (Dpd) and N-telopeptide of type I of collagen (NTx), two bone resorption markers, returned to the control range by day 30 and decreased thereafter. Increased levels of patients' serum tumor necrosis factor-alpha (TNFalpha) and interleukin-1beta (IL-1beta), two bone resorbing cytokines, returned to the control range by day 30 and decreased thereafter. Peripheral blood neutrophil counts increased by day 30 and continued to rise thereafter, reaching a mean value higher than 2650 neutrophils per microl of blood on day 360. Interestingly, alendronate-induced changes in the levels of both cytokines correlated inversely with the respective changes in neutrophil counts and BMD measurements, and positively with the changes in the respective means of urine NTx and Dpd values. All these findings indicate that alendronate is effective in treating CIN-associated osteopenia/osteoporosis, and that the beneficial effect of the compound may lie, at least in part, in its property to inhibit the production of TNFalpha and IL-1beta by cells of the monocyte/macrophage system, in which osteoclasts are included.

Cyclosporine A-induced hypercalciuria in calbindin-D28k knockout and wild-type mice

BACKGROUND

It is known that cyclosporine A (CsA) treatment induces high bone-turnover osteopenia and hypercalciuria. It has been proposed that down-regulation of renal calbindin-D28k by CsA results in renal calcium wasting. We investigated the role of the kidney and bone in CsA-induced hypercalciuria in calbindin-D28k knockout (KO) and wild-type (WT) mice.

METHODS

Two sets of experiments were performed. In experiment 1, KO and WT mice were treated with CsA 20 mg/kg/day intraperitoneally (IP) for 7 days. In experiment 2, to eliminate the CsA effect on bone resorption, pamidronate (APD) 2.5 mg/kg IP was given every 4 days with the first dose given 4 days prior to the 7-day course of CsA. Serum levels of creatinine, calcium, and osteocalcin, as well as renal calcium excretion were measured to assess CsA's effects on calcium homeostasis. Effects of CsA on the expression of calbindin-D28k, and two calcium channels in the apical membrane of the distal tubule, epithelial calcium channel (ECaC) and alpha1G-subunit of a voltage-dependent Ca channel (alpha1G), in the kidney were examined by semiquantitative reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

KO mice had a threefold increase in renal calcium excretion when compared with WT mice at the baseline. This difference disappeared when calcium load was reduced by overnight fasting. After the CsA treatment, both WT and KO mice had a significant increase of renal calcium excretion (urine Ca/Cr ratio in WT, 0.11 +/- 0.01 to 1.29 +/- 0.17; in KO, 0.39 +/- 0.04 to 1.18 +/- 0.13; both P < 0.01). CsA treatment decreased renal calbindin-D28k mRNA by 61%, but did not affect the expression of ECaC and alpha1G. Baseline serum osteocalcin level of KO mice was significantly lower than that of WT mice. After CsA treatment, both groups had a 50% increase in the serum osteocalcin level, indicating increased bone turnover. When mice were treated with both CsA and APD, the increase in serum osteocalcin level was prevented, and renal calcium excretion was significantly lower than that in mice treated with CsA alone. However, there was still a significant increase in the urine Ca/Cr ratio in WT and KO mice compared with pretreatment levels (urine Ca/Cr in WT, 0.11 +/- 0.01 to 0.76 +/- 0.05, P < 0.01; in KO, 0.39 +/- 0.05 to 0.79 +/- 0.06; P < 0.01).

CONCLUSION

Calbindin-D28k KO mice have diet-dependent hypercalciuria and a lower bone turnover rate. CsA treatment suppresses the expression of calbindin-D28k in mice, but has no effects on ECaC and alpha1G gene expression at the mRNA level. The pathogenesis of CsA-induced hypercalciuria involves both down-regulation of calbindin-D28k with subsequent impaired renal calcium reabsorption and CsA-induced high turnover bone disease. Additionally, our results suggest that mechanism(s) independent of calbindin-D28k within the kidney also may contribute to the CsA-induced calcium leak.

Prevention of spinal bone loss by potassium citrate in cases of calcium urolithiasis

PURPOSE

We determine if potassium citrate treatment stabilizes spinal bone density among patients with recurrent calcium oxalate nephrolithiasis.

MATERIALS AND METHODS

We studied a group of 16 men and 5 women with stones taking potassium citrate from 11 to 120 months. They represented all patients from the Stone Clinic who took potassium citrate alone for at least 11 months. L2-L4 bone mineral density data before and after potassium citrate treatment were retrieved retrospectively and analyzed.

RESULTS

In the combined group L2-L4 bone mineral density increased significantly by 3.1% over mean duration of 44 months. Z score, corrected for age matched normal values, increased significantly by 3.8%. Urinary pH, citrate and potassium increased significantly during treatment but urinary calcium did not change.

CONCLUSIONS

Potassium citrate, a commonly used drug for the prevention of recurrent nephrolithiasis, may avert age dependent bone loss. Spinal bone density increased in most patients when it normally decreases.

Spot urine analysis: acidification does not increase calcium recovery

INTRODUCTION

We investigated the effects of acidification and storage on calcium recovery in spot urine samples.

METHODS

In a retrospective study, 43 spot urine samples from patients with metabolic bone disease, which had been previously analysed fresh for calcium and creatinine, were acidified and incubated for 2 h at room temperature and re-analysed. In a prospective study, fresh spot urine samples from 15 volunteers were split into two aliquots--one left unacidified and the other acidified with 6 mol/L HCl to pH < 2. Both aliquots were analysed immediately and after storage at 4 degrees C for 24 h.

RESULTS

In both studies, the calcium creatinine ratios obtained on acidified and non-acidified spot urine samples were not different, both when measured immediately as well as after storage at 4 degrees C for 24 h.

CONCLUSIONS

The acidification of spot urine samples would thus appear to be unnecessary for calcium/creatinine measurements in metabolic bone disease if they were undertaken within at least 24 h.

Bone resorption in post-menopausal women with normal and low BMD assessed with biochemical markers specific for telopeptide derived degradation products of collagen type I

Biochemical markers of bone resorption can be used clinically to predict the risk of osteoporosis-related fractures (prognostic tool) and to assess the response of an osteoporotic patient to an antiresorptive therapy (monitoring tool). Our aim was to assess the ability of four currently marketed biochemical markers of bone resorption, based on the measurement of degradation products from collage type I telopeptides to monitor the elevated resorption associated with menopause. Women (846) were stratified for menopause, age, and bone mineral density and the following markers were measured: urinary cross-linked N-telopeptides of type I collagen (NTx), the levels of breakdown products of type I collagen C-telopeptides in serum (S-CTx), and in urine, by ELISA (U-CTx-E), and RIA (U-CTx-R). Furthermore, the ratio (alpha/beta) between the alphaL form of CTx measured in the CTx RIA and the betaL form measured in the ELISA was calculated. The mean difference was calculated for each marker in women with osteopenia (Op) or osteoporosis (PMO) (WHO definition) compared with healthy premenopausal (Pre) women and postmenopausal (N Post) women with normal bone mass. Serum CTx showed the highest elevation in post- compared with premenopausal women. All marker values were significantly higher in Op and PMO subjects compared with both Pre and to N Post women. Compared with premenopausal values, the largest elevation in both Op and PMO women was observed for serum CTx. Compared with N Post, urine NTx showed the highest increase in OP subjects. The alpha/beta CTx ratio was elevated in post- compared with Pre women, but there was no difference in the ratio among N Post, Op, or PMO women. In conclusion, postmenopausal women showed elevated turnover with all bone resorption markers, but with substantial individual variation in resorption levels. Furthermore, the turnover process in postmenopausal women appears to be quantitatively different from the premenopausal stage, apparent as altered alpha/beta CTx ratios.

The effects of nandrolone decanoate on bone mass and metabolism in ovariectomized rats with osteopenia

The effects of nandrolone decanoate (ND) treatment on bone mass and metabolism were studied in ovariectomized (OVX) rats with osteopenia. The 6-month-old rats were divided into Sham (n = 12) and OVX (n = 24). The OVX rats were allowed to lose bone for 6 weeks. At 6 weeks post ovariectomy, the OVX rats were divided into two groups: (1) OVX + Vehicle and (2) OVX + ND. The effects of ND on bone mineral density (BMD), bone mineral content (BMC), and bone metabolism were studied by dual-energy X-ray absorptiometry (DXA) and biochemical markers including urinary pyridinoline (Pyr), deoxypyridinoline (Dpyr), and serum osteocalcin. After 24 weeks of treatment, histomorphometry of the right tibiae and the wet weight of the gastrocnemius and soleus skeletal muscles were also examined. Ovariectomy resulted in a significant increase in biochemical markers and a significant decrease in spine BMD (0.221+/-0.016g/cm2 in OVX group vs 0.239+/-0.008g/cm2 in Sham group) and BMC (0.550+/-0.055g in OVX group vs 0.605+/-0.042g in Sham group) at 6 weeks post ovariectomy. Spine BMD (0.227+/-0.017g/cm2), femoral BMD (0.263+/-0.012g/ cm2), and bone density of femur (1.035+/-0.036g/cm3) in the OVX + ND group were significantly greater than those in the OVX + Vehicle group (0.204+/-0.013g/cm2 for spine BMD, 0.243+/-0.009g/cm2 for femoral BMD, 0.938+/-0.06g/cm3 for bone density of femur) after 24 weeks of treatment. ND treatment decreased urinary Pyr and Dpyr significantly in OVX rats. Histomorphometric findings indicated that ND-treated rats had greater cancellous bone volume, greater trabecular number, greater trabecular thickness, and less trabecular separation than vehicle-treated OVX rats. OVX rats had greater wet weight of the gastrocnemius and soleus muscles than rats treated with ND. The data suggest that the effect of ND on bone mass is not influenced by the condition of the muscles in OVX rats. Our findings indicate that ND blocks further bone loss by inhibition of bone resorption in OVX rats with osteopenia.

Serum concentrations of interleukin 6, osteocalcin, intact parathyroid hormone, and markers of bone resorption in patients with rheumatoid arthritis

OBJECTIVE

To analyze serum concentrations of interleukin 6 (IL-6), osteocalcin, intact parathyroid hormone (PTH), and type 1 collagen carboxyterminal telopeptide (ICTP) as well as the urinary concentrations of crosslinked N-telopeptides of type 1 collagen (NTx) and deoxypyridinoline (Dpd) in patients with rheumatoid arthritis (RA) to investigate their role in the etiology of the osteopenia in this disease.

METHODS

Using ELISA and radioimmunoassay methods, we estimated serum concentrations of IL-6, osteocalcin, ICTP, intact PTH, and spot urine concentrations of NTx and Dpd in 25 female patients with active RA, 25 female patients with suppressed disease, and 25 age matched healthy female controls.

RESULTS

Patients with active RA had significantly higher (p < 0.001) concentrations of IL-6 (94.0+/-12.1 pg/ml) compared to patients with suppressed disease (13.2+/-0.8 pg/ml) and healthy controls (12.3+/-0.8 pg/ml). Serum osteocalcin was significantly lower (p < 0.001) in patients with active RA (1.9+/-0.2 ng/ml) compared to patients with suppressed disease (2.7+/-0.2 ng/ml) and the controls (2.9+/-0.2 ng/ml). Similarly, serum intact PTH was significantly lower (p < 0.001) in patients with active disease (29.9+/-1.5 ng/ml) compared to patients with suppressed RA (38.0+/-1.6 ng/ml) and controls (49.8+/-2.4 ng/ml). Serum ICTP was also significantly higher (p < 0.01) in patients with active RA (9.5+/-0.3 microg/l) versus patients with suppressed disease (4.1+/-0.2 microg/l) and controls (3.4+/-0.2 microg/l). In patients with active disease, spot urine concentrations of NTx (123.1+/-5.1 nmol bone collagen equivalent/mmol creatinine) and Dpd (15.1+/-0.7 nmol/mmol creatinine) were significantly higher (p < 0.001) than in patients with suppressed disease (58.4+/-2.5 nmol bone collagen equivalent/mmol creatinine and 10.1+/-0.5 nmol/mmol creatinine, respectively) and healthy controls (53.4+/-2.1 nmol bone collagen equivalent/mmol creatinine and 9.7+/-0.5 nmol/mmol creatinine, respectively). There were no significant correlations between serum IL-6 and serum ICTP (r = 0.2357, p = 0.257) or urinary NTx (r = 0.1436, p = 0.494) or between serum intact PTH and ICTP (r = 0.0206, p = 0.922) in patients with active RA.

CONCLUSION

There are no significant correlations between bone resorption markers and serum IL-6 and intact PTH in patients with RA.

Bone turnover in preterm infants

Total parenteral nutrition is associated with osteopenia in preterm infants. Insufficient calcium and phosphate are likely causes: aluminum contamination is another possible contributing factor as this adversely affects bone formation and mineralization. The study was designed to evaluate changes in biochemical markers of bone turnover in 22 preterm infants receiving total parenteral nutrition in comparison with 19 term infants. We collected urine and serum samples from 22 preterm infants, mean gestational age 29 wk, within 48 h and again at 3 wk of life. We also collected urine samples from 19 term infants, mean gestational age 39 wk, during the first day of life. Bone resorption was assessed by the measurement of urinary pyridinium cross-links by HPLC and ELISA and the N-telopeptide of type I collagen by ELISA. Bone formation was assessed in premature infants by the measurement of serum osteocalcin. The N-telopeptide of type I collagen was higher in the preterm infants compared with term at baseline (p < 0.01). There was no difference between the pyridinium cross-links in the preterm and term infants. All the biochemical markers of bone turnover increased significantly in the preterm infants during the first 3 wk of life, e.g. N-telopeptide was a 153% change from baseline (p < 0.001). Aluminum in the total parenteral nutrition solutions did not cause a decrease in bone formation at the level administered (3-6 microg, 0.1-0.2 micromol x kg(-1) x d(-1)).

Treatment effects of bisphosphonates on ovariectomy-induced osteopenia in rats: comparison between clodronate and etidronate

We studied the effects of clodronate and etidronate on bone loss induced by ovariectomy (OVX) in rats. Drug administration was initiated 8 weeks after the surgery and continued for 12 weeks (twice per week, s.c.). Lumbar (L4-L5) bone mineral density (BMD) and femoral BMD in the sham-operated group were increased to 113% and 114%, respectively, whereas those in OVX group were suppressed to 98.8% and 105%. Clodronate significantly restored the suppressed BMD over the entire dose range used (4-25 mg/kg). Etidronate restored BMD only at 4 mg/kg. In a histomorphometric analysis of lumbar vertebrae, both bisphosphonates depressed the amount of labeled surface, which was increased by OVX, to 11.9%-20.1% of the OVX group value for clodronate and to 0.23%-9.7% of the OVX group value for etidronate. The osteoid area was significantly increased by etidronate treatment over the entire dose range (OS/BS, 175%-295%). On the other hand, the osteoid area in the clodronate group did not increase at any dose tested (OS/BS, 38.1%-49.9%). Urinary excretion of deoxypyridinoline and plasma level of osteocalcin were elevated in the OVX group (162%-182% and 123%, respectively), suggesting that OVX enhanced bone turnover. Both bisphosphonates suppressed the bone turnover accelerated by OVX, and the data indicated that both bisphosphonates recovered BMD by means of inhibition of bone resorption. These data suggested that clodronate and etidronate reversed osteopenia induced by ovariectomy in rats. As judged from the dose response of BMD and histomorphometric findings, clodronate showed a wider safety margin than etidronate.

Femoral neck osteopenia in patients with inflammatory bowel disease

OBJECTIVE

The mechanism of bone loss in patients with inflammatory bowel disease (IBD) is not completely understood. The aim of this study was to assess indices of bone turnover and bone mineral density (BMD) in the lumbar spine and femoral neck in IBD patients.

METHODS

Sixty-three patients with Crohn's disease and 41 with ulcerative colitis were studied. Serum bone-specific alkaline phosphatase (B-ALP), osteocalcin, parathyroid hormone (PTH), 25 hydroxyvitamin D, interleukin-6 (IL-6), and urinary N-telopeptide cross linked type 1 collagen (NTX) were determined. BMD of the lumbar spine and femoral neck was determined by dual x-ray absorptiometry in 59 patients.

RESULTS

In the femoral neck 42% of the patients had osteopenia (-2.5 SD < BMD T score < -1 SD) and another 41% had osteoporosis (BMD T score < -2.5). In the spine 34% of the patients had osteopenia and additional 42% had osteoporosis. BMD T scores were lower in the femoral neck compared to the spine. Reduced BMD was unrelated to gender, disease type, lifetime corticosteroid dose, but inversely correlated with disease duration (r = -0.36, p < 0.05). Serum IL-6 was higher in IBD patients compared to controls. A reduced level of osteocalcin, a marker of bone formation, was present in 7% of patients and an increase in NTX, a marker of bone resorption, in 25% of them. Osteoporotic IBD patients (spine or hip BMD T score < -2.5) had increased serum IL-6, osteocalcin and PTH level compared to nonosteoporotic patients.

CONCLUSIONS

There is a high prevalence of reduced BMD at the spine and femoral neck in IBD patients, which is more severe in the hip. Bone turnover in osteoporotic IBD patients is associated with an increase in osteocalcin, PTH and IL-6. IL-6 may play a role in the pathogenesis of bone loss in IBD.

Markers of bone remodelling in metabolic bone disease

New specific markers of bone remodelling have been developed that allow the evaluation of bone formation (plasma levels of osteocalcin and bone alkaline phosphatases) or bone resorption (collagen crosslink levels in urine). These markers can be used to evaluate bone disease. Their best application is currently in renal osteodystrophy, where there is a broad spectrum of bone abnormalities. In patients with this disease, bone markers can obviate the need for bone biopsy. So far, bone alkaline phosphatase is the most sensitive and specific marker for predicting the type of bone disease and therefore for deciding treatment in dialysed patients, although it is not ideal. Bone markers have also allowed a dramatic improvement in the comprehensive approach to bone loss with aging in women. Monitoring of the marked increase in bone turnover, and its persistence, in older women after menopause may help in the design of treatment strategies for osteoporosis. There is some hope that the measurement of urinary levels of collagen crosslinks will help to predict the clinical outcome of osteoporosis with respect to fractures in postmenopausal women. Bone markers could, besides being a measurement of bone density, help to determine the optimal treatment of postmenopausal women. Bone markers could also be used to predict or ascertain the response to treatment of osteoporosis, but few data are currently available to judge the routine usefulness of these new applications.

Pathophysiology and treatment of idiopathic hypercalciuria

Nearly 50 years after its initial description by Dr. F. Albright, the term idiopathic hypercalciuria (IH) is still in use. The exact mechanism of hypercalciuria is still unknown despite extensive pathophysiologic investigations; recent advances represent the focus of this review. A precise definition of true IH is proposed, taking into account the various nutritional conditions influencing calcium excretion. The potential pathogenic mechanisms are discussed, and the limits of the classical Pak's pathophysiological classification are recalled. The evidence supporting the role of an increased intestinal calcium absorption, a defect in renal tubular calcium reabsorption, or an increased bone loss as a primary mechanism in IH are successively examined. Since overall available human data indicates that all three mechanisms may be found in IH, the hypothesis that a broader disorder encompassing all these various abnormalities may be involved in IH is discussed. Three global hypotheses to account for IH physiopathology are examined: a diffuse defect in fatty acid content of cell membranes, an increased expression of the vitamin D receptor of the 25(OH) vitamin D 1 alpha-hydroxylase, or of the calcium sensor receptor and a monocyte disease. Finally, the available clinical data justifying the therapeutic approaches are reviewed, and guidelines for dietary recommendations regarding calcium and also animal protein, sodium chloride, alcohol, carbohydrate, phosphate, and potassium intakes are proposed, and drug therapy indications are discussed.

Changes in biochemical markers and bone mass after withdrawal of ibandronate treatment: prediction of bone mass changes during treatment

The study was a 1 year randomized, double-blind, placebo-controlled study of ibandronate treatment in postmenopausal, osteopenic women. Participants were followed for 1 year after withdrawal of treatment. All women were at least 10 years past menopause and had a baseline bone mineral density (BMD) at the distal forearm at least 1.5 standard deviations below the premenopausal mean peak value. A total of 141 women (78%) completed the first year, and 119 women (66%) the second year of the study. The dose-response data of the first year have been published previously (Ravn et al. Bone 19:527-533;1996). In this study, we analyzed the biochemical markers as predictors of response in bone mass during ibandronate treatment, and report withdrawal data from the last year of the study, when ibandronate was discontinued. The relative change in the biochemical markers was significantly correlated to the response in BMD. At 12 months, the r values ranged from -0.29 to -0.47 (p < 0.01) and were highest for CrossLaps (uCL) and osteocalcin (OC(N-MID)). The quartiles of women with the most reduced concentrations of uCL and OC(N-MID) during treatment showed a 360-430% higher response in BMD compared to quartiles with less reduced concentrations (p < 0.01). During the withdrawal period, uCL and alkaline phosphatase (AP) returned to baseline values 12 months after discontinuation of treatment in all groups, whereas OC(N-MID) and bone-specific AP were still reduced 10%-25% in the groups previously treated with the highest doses of ibandronate (1.0-5.0 mg) (p < 0.01). In the withdrawal period, BMD decreased equally in all groups (analysis of variance; not significant); with a linear rate of 2%/year on average (p < 0.05 to < 0.001) at the spine and femur. In conclusion, uCL and OC(N-MID) can be used to predict the response in bone mass during ibandronate treatment. The bone loss that resumes after withdrawal of ibandronate treatment is of a magnitude similar to that of normal postmenopausal bone loss.

High-turnover osteopenia in preterm infants: determination of urinary pyridinium cross-links of collagen

Osteopenia is a frequent condition in preterm infants, but its pathogenesis is uncertain. In the present study, we measured longitudinal changes in the excretion of pyridinium cross-links of collagen (specific markers of bone resorption) and evaluated the relationship between collagen cross-links and other indexes of bone and renal function in preterm infants. In these infants, urinary collagen cross-links were markedly increased on day 7 and day 30 of life and at estimated full-term gestation. The values were several times higher than those of older children and almost comparable to those of healthy full-term infants. Cross-link excretion did not correlate with beta2-microglobulin (B2M) or N-acetyl-beta-D-glucosaminidase (NAG) activity (markers of renal function), indicating that cross-link excretion is not influenced directly by infantile renal function. High serum osteocalcin and low bone mineral density (BMD) in the lumbar spine were also observed at estimated full-term gestation. There was no significant correlation between collagen cross-link excretion and either serum osteocalcin or spine BMD. We conclude that a state of high bone turnover underlies the development of osteopenia in preterm infants.

Characteristics of biochemical markers in patients with metabolic bone disorders

Biochemical markers of bone turnover are expected to have some different characteristics among bone metabolic disorders. We compared bone formation markers: serum total alkaline phosphatase (s-Alp), serum osteocalcin (s-OC) and serum carboxy-terminal propeptide of type I collagen (s-PICP); and bone resorption markers: serum carboxy-terminal telopeptide of type I collagen (s-ICTP), urinary pyridinoline (u-Pyr) and urinary deoxypyridinoline (u-Dpyr) to examine which marker is the most suitable and reliable to evaluate bone turnover in patients with osteoporosis (n = 29), osteomalacia (n = 10), primary hyperparathyroidism (n = 6) and renal osteodystrophy (n = 21). The value of s-Alp in the osteomalacia group was significantly higher than those in the normal control group and the osteoporosis group (p < 0.001), and T-score of s-Alp was significantly higher than those of s-OC and s-PICP in the osteomalacia group. The values of u-Pyr and u-Dpyr in the primary hyperparathyroidism group were significantly higher than those in the other groups (p < 0.001). S-PICP, which are not dependent upon renal function, was much higher in the renal osteodystrophy group than in all other groups. In the osteoporosis group, T-score of s-ICTP was significantly higher than those of s-OC. Thus, s-Alp was a good marker in osteomalacia, u-Pyr and u-Dpyr in primary hyperparathyroidism, s-PICP in renal osteodystrophy, and s-ICTP in osteoporosis.

Microalbuminuria as an early indicator of osteopenia in male insulin-dependent diabetic patients

Reduced bone mineral density (BMD), termed diabetic osteopenia, has been reported in patients with insulin-dependent (Type 1) diabetes mellitus (IDDM). To examine BMD in long-term IDDM patients with normal kidney function, but with different degrees of urinary albumin excretion rate (UAER), compared to that of patients with elevated plasma creatinine, 36 IDDM male patients (mean duration 27 years) were subdivided according to UAER (<30, 30-300, >300, >300 mg 24 h(-1) and plasma creatinine 0.120-0.350 mmol l(-1)) and 15 controls were recruited. BMD was measured by dual energy X-ray absorptiometry and UAER by enzyme linked immunosorbent assay. BMD was normal in IDDM patients with normal UAER and reduced in the femoral neck, the trochanter major, and the Wards triangle in patients with increased UAER (p < 0.01, p < 0.05, p < 0.02). BMD correlated to creatinine clearance in both cortical and cancellous bone sites (p < 0.001, p < 0.0001), and inversely to the levels of plasma PTH (p < 0.0005). We conclude that BMD is normal in long-term IDDM male patients with normal kidney function and normal UAER and reduced in patients with increased UAER. Diabetic osteopenia seems to be a progressive phenomenon related to diabetic nephropathy and associated with the decrease in creatinine clearance and with the resulting rise in plasma PTH.

Urinary N-telopeptide levels discriminate normal, osteopenic, and osteoporotic bone mineral density

BACKGROUND

The level of urinary, type I collagen, crosslinked N-telopeptides (NTX) is a new marker of bone resorption. To our knowledge, no population-based studies of older adults have determined whether this measure can identify individuals with osteoporosis.

OBJECTIVES

To measure the levels of NTX in a cross-sectional study of ambulatory, older, white adults and to evaluate whether this measure of bone resorption could identify individuals with osteoporosis.

PATIENTS AND METHODS

The subjects, aged 50 to 98 years, formed 3 groups: 374 men, 223 women currently using estrogen, and 364 women not currently using estrogen. A standard medical history and validated record of medication use were obtained. Height and weight were measured. Bone mineral density (BMD) was measured at the hip and lumbar spine using dual energy x-ray absorptiometry. The levels of NTX were measured by enzyme-linked immunosorbent assay.

RESULTS

Overall, the levels of NTX increased slightly with age in men and in estrogen users and more dramatically in nonestrogen users. In a model adjusted for all major risk factors for osteoporosis, there was a significant decrease in BMD levels by increasing quintiles of NTX levels at the hip and spine in women with and without estrogen use and at the hip in men. Using sex-specific, peak bone mass criteria and age-adjusted analyses, the levels of NTX discriminated between normal (< or = -1.0 SD), osteopenic (> -1.0 and < -2.5 SD), and osteoporotic (> or = -2.5 SD) BMD levels in all groups except the spine in men.

CONCLUSIONS

The levels of NTX uniquely discriminated between older adults with normal, osteopenic, or osteoporotic BMD levels. If confirmed, these data suggest that NTX levels could be used to predict current osteoporosis in older men and women.

Altered hydroxylation of estrogen in patients with postmenopausal osteopenia

To study the possible contributions of the differences in estrogen metabolism to bone mass in postmenopausal osteopenia, spinal and femoral bone mineral densities (BMD) were measured, and 18 urinary metabolites of estrogen were analyzed by a gas chromatography-mass spectrometry assay system in 59 postmenopausal women (5-10 yr after menopause). The BMD of the spine and femoral neck showed positive correlations with body weight, height, and body mass index as we expected. Compared to nonosteopenic subjects, there were no significant differences in serum estrone (E1) and estradiol (E2) levels in patients with osteopenia. However, the urinary 16 alpha-hydroxyestrone [16 alpha-(OH)E1] level was significantly lower in patients with spinal osteopenia (P < 0.001). Among the 18 urinary metabolites of estrogen, the 16 alpha-(OH)E1 and 16 alpha-(OH)E1/2-hydroxyestrone [2-(OH)E1) ratio showed positive correlations with spinal BMD (P < 0.05), whereas 2-(OH)E2 showed a negative correlation with femoral neck BMD (P < 0.05). The urinary 16 alpha-(OH)E1 level also revealed a positive correlation with the age-matched z score of BMD in the spine (P < 0.05). In multiple stepwise regression analysis, weight, 16 alpha-(OH)E1, interaction between 16 alpha-(OH)E1 and 2-(OH)E2, 2-(OH)E2, and years after menopause were statistically significant for spinal BMD (r2 = 0.4968). For femoral neck BMD and weight, 16 alpha-(OH)E1 and 2-(OH)E2 were the independent determinants (r2 = 0.3369). In conclusion, the activity of estrogen 16 alpha-hydroxylase was decreased and/or the activity of estrogen 2-hydroxylase was enhanced in post-menopausal osteopenia. We speculated that these derangements may serve as contributing factors for the acceleration of bone loss in post-menopausal osteoporosis.

Osteoporosis and bone mineral metabolism disorders in cirrhotic patients referred for orthotopic liver transplantation

The purpose of this study was to determine the prevalence of osteoporosis, to estimate the bone turnover and hormonal status, and to identify the factors associated with bone disease in patients with end-stage liver disease who were referred for orthotopic liver transplantation. A prospective study was performed on 58 cirrhotic patients (6 with primary biliary cirrhosis, 14 with alcoholic cirrhosis, and 38 with posthepatitic cirrhosis), who were referred for orthotopic liver transplantation. Patients, excluding those with primary biliary cirrhosis, were classified in Child-Pugh groups according to the severity of liver disease (class B [28 patients], class C [24 patients]). Biochemical parameters of bone mineral metabolism and standard liver function tests were measured in all patients. Additionally, serum osteocalcin, urinary hydroxyproline/creatinine ratio, serum intact parathyroid hormone, serum 25-hydroxyvitamin D, serum 1,25-dihydroxyvitamin D, follicle-stimulating hormone, and luteinizing hormone levels were determined in patients and controls within the same age range. Plasma testosterone, sex hormone-binding globulin levels, and free testosterone index were obtained for all men included in the study. Bone mass of the lumbar spine and femur were measured by dual X-ray absorptiometry (DPX-L), and were expressed as a standard deviation of mean values (Z-score) from a sex and age-matched control group. Spinal X-rays were obtained to assess vertebral fractures. Osteoporosis was considered as a factor in spinal bone mineral density with a Z-score below 2 or at least one vertebral fracture. Twenty-five patients (43%) had osteoporosis, with lower bone mass measurements in the lumbar spine than in the femoral neck (P < 0.005). Alcoholic and Child-Pugh C patients showed the lowest femoral bone mineral density values. Cirrhotic patients showed lower osteocalcin levels than controls (14.3 +/- 5.9 vs. 18.2 +/- 8.1 ng/ml; P < 0.05) and showed increased urinary hydroxyproline (125.1 +/- 51.5 vs. 107.9 +/- 26.6 nM/mg creatinine; P < 0.05). Serum 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D and parathyroid hormone levels were significantly lower in cirrhotic patients than in controls (10.3 +/- 9.1 vs. 23.1 +/- 26.6 ng/ml; P = 0.000), (12.9 +/- 9.1 vs. 48.3 +/- 11.5 pg/ml; P = 0.000), (16.6 +/- 9.2 vs. 27.9 +/- 8.2 pg/ml; P = 0.000), with no differences between Child-Pugh groups. Alcoholic Child-Pugh C patients showed the lowest 25-hydroxyvitamin D serum values (4.5 +/- 2.2 ng/ml; P < 0.05). Male patients had lower testosterone levels than controls (302.5 +/- 229.4 vs. 556.7 +/- 146.5 ng/dl; P = 0.000), with increased sex hormone-binding globulin values. Levels of testosterone and gonadotropin were related to Child-Pugh classification. No correlation was found between bone mass and hormonal values. A significant decrease in bone mass, particularly in the lumbar spine, is seen in end-stage cirrhotic patients. Reduced bone formation and significant disorders of bone mineral metabolism, such as vitamin D deficiency, reduced parathyroid hormone levels, and hypogonadism are involved. Moreover, severity and etiology of the liver disease are the main risk factors for developing bone loss and mineral metabolism disorders in patients referred for orthotopic liver transplantation.

Aminohexane bisphosphonate suppresses bone turnover in postmenopausal women more rapidly than oestrogen-gestagen therapy

Although animal studies suggest that there may be major differences between the effects of bisphosphonates and ovarian hormones on skeletal metabolism, whether this also holds for their actions in patients is unknown. To address this question, we compared the effects of 12 weeks treatment with HRT on bone turnover markers in osteopenic postmenopausal women with those of an amino-bisphosphonate. Women within 15 yr of the menopause, with a lumbar and/or femoral neck bone mineral density 1 S.D. below the predicted value, received either oestradiol valerate 2 mg and dydrogesterone 5 mg (E/D; n = 16) or aminohexane bisphosphonate 400 mg (AHBP; n = 9). Urine and serum samples were collected on two separate occasions before starting treatment, and 1, 2, 4, 8 and 12 weeks afterwards. To assess bone resorption, we measured the urinary deoxypyridinoline/creatinine ratio (DPD/crea), while serum alkaline phosphatase (ALP), osteocalcin and C-terminal propeptide of type I collagen (CICP) were analysed to assess bone formation. Repeated measures analysis of variance revealed a highly significant decrease in DPD/crea over the treatment period. Furthermore, this pattern of response differed significantly between the two treatment groups, since DPD/crea was maximally suppressed within 2 weeks of starting AHBP, while E/D showed little decrease until 8 weeks. AHBP was also found to suppress ALP, osteocalcin and CICP more rapidly than E/D, the former reducing these markers by 8 weeks, while E/D caused little inhibition even by 12 weeks. We conclude that, in the doses used in this study, AHBP appears to suppress bone turnover significantly more rapidly than E/D, suggesting that clinically important differences may exist in the effects of bisphosphonates and ovarian hormones on bone metabolism.

Assessment of urinary pyridinoline excretion with a specific enzyme-linked immunosorbent assay in normal adults and in metabolic bone diseases

Pyridinoline (Pyr), a specific bone resorption marker, is usually assessed in urine by high-performance liquid chromatography (HPLC) after acid hydrolysis and a prepurification step. Immunoassays have been developed to measure urinary Pyr directly. Here we developed and evaluated an enzyme-linked immunosorbent assay (ELISA), specific for the urinary free Pyr form, in normal adults and in patients with metabolic bone diseases. Urinary Pyr excretion increased significantly with age for men (r = 0.288; p < 0.001) and for women (r = 0.362; p < 0.001). An average 55% increase was noted between premenopausal (n = 41) and early postmenopausal (n = 42) women (mean +/- 1 SD; 22.4 +/- 6.3 nmol Pyr/mmol creatinine and 34.7 +/- 16.8 nmol Pyr/mmol creatinine, respectively; p < 0.001). High Pyr levels were found in patients with hyperthyroidism (n = 29; 126.5 +/- 84.2 nmol Pyr/mmol creatinine), Paget's disease of bone (n = 30; 61.8 +/- 45.8 nmol Pyr/mmol creatinine), and primary hyperparathyroidism (n = 10; 57.4 +/- 23.9 nmol Pyr/mmol creatinine). In patients with Paget's disease, urinary free Pyr excretion was correlated with urinary hydroxyproline, the conventional bone resorption marker (r = 0.87; p < 0.001), and with total alkaline phosphatase, a marker of bone formation (r = 0.55; p < 0.005). Free Pyr measured by ELISA was highly correlated with total Pyr and with total deoxypyridinoline HPLC measurements in postmenopausal women (n = 35; r = 0.94 and 0.91, respectively) and in patients with metabolic bone diseases (n = 22; r = 0.91 and 0.88, respectively; p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

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.