Early treatment with zoledronic acid prevents bone loss at the hip following acute spinal cord injury

Osteoporosis after spinal cord injury is common. Reductions in bone density are rapid and fracture rates are higher after injury. Early treatment with 4 mg zoledronic acid significantly reduced bone loss at the hip compared to untreated individuals in the first year. Treatment appeared safe and well tolerated.

INTRODUCTION

Bone mineral density (BMD) is lost rapidly following spinal cord injury (SCI), predominantly in the lower limbs. Bone turnover markers suggest an early increase in resorption.

METHODS

A randomised, open-label study of 14 patients with acute SCI randomised to receive 4 mg IV zoledronic acid or standard treatment. BMD was measured by dual-X-ray absorptiometry at the lumbar spine and hip (femoral neck, total and trochanter) at baseline, 3, 6 and 12 months. Bone turnover markers (serum C-terminal telopeptide and Procollagen I N-terminal peptide and urinary N-terminal telopeptide/Cr ratio) were also measured.

RESULTS

After 12 months, there was a significant difference in BMD between the groups at the total hip (12.4%, p = 0.005), trochanter (13.4%, p = 0.028) and lumbar spine (2.7%, p = 0.033). However, the difference between groups at the femoral neck was not significant (4.8%, p = 0.741). In the treated group, bone resorption was reduced and remained reduced up to 12 months. Other than flu-like symptoms immediately after the infusion, no adverse events were observed.

CONCLUSION

IV zoledronic acid is an effective and well-tolerated treatment to prevent bone mineral density loss at the total hip and trochanter for up to 12 months following SCI.

Vitamin D deficiency in patients with osteoarthritis undergoing total hip replacement: a cause for concern?

We measured the plasma 25-hydroxyvitamin D(3) (25(OH)D(3)) levels in 62 consecutive Caucasian patients undergoing total hip replacement for osteoarthritis. The patients were divided into two groups based on whether they were vitamin D sufficient or deficient. The groups were matched for age, gender and the American Society of Anaesthesiologists (ASA) grade. The prevalence of vitamin D deficiency in our patients was comparable with recent population-based studies performed in the United Kingdom. Patients with vitamin D deficiency had lower pre-operative Harris hip scores (Mann-Whitney test, p = 0.018) and were significantly less likely to attain an excellent outcome from total hip replacement (chi-squared test, p = 0.038). Vitamin D levels were found to positively correlate with both pre- and post-operative Harris hip scores. These results warrant further study of vitamin D deficiency in patients undergoing joint replacement as it is a risk factor for a suboptimal outcome which is relatively simple and cheap to correct.

The genetic causes of basal ganglia calcification, dementia, and bone cysts: DAP12 and TREM2

BACKGROUND

Polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy (PLOSL), or Nasu-Hakola disease, is a presenile dementia associated with loss of myelin, basal ganglia calcification, and bone cysts. It is caused by recessively inherited mutations in two genes encoding subunits of a cell membrane-associated receptor complex: TREM2 and DAP12. The clinical course of PLOSL has not been characterized in a series of patients with TREM2 mutations.

METHODS

The authors compare neurologic and neuroradiologic follow-up data of six patients carrying TREM2 mutations with PLOSL due to defective DAP12 genes. The authors review the known mutations in these two genes.

RESULTS

Mutations in DAP12 and TREM2 result in a uniform disease phenotype. In Finnish and Japanese patients with PLOSL, DAP12 mutations predominate, whereas TREM2 is mutated more frequently elsewhere.

CONCLUSIONS

Polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy should be considered in adult patients under age 50 years with dementia and basal ganglia calcification. Radiographs of ankles and wrists, and DNA test in uncertain cases, confirm the diagnosis.

Size at birth, adult intestinal calcium absorption and 1,25(OH)(2) vitamin D

BACKGROUND

Adult bone mineral status is modified by early environmental influences, but the mechanism of this phenomenon is unknown. Intestinal calcium absorption and vitamin D metabolism are integrally involved in bone metabolism and may be programmed during early life.

AIM

To examine the early-life influences on calcium absorption and its control in 322 post-menopausal female twins.

METHODS

Intestinal calcium absorption was assessed by the stable strontium (Sr) method. Serum PTH, 25(OH) and 1,25(OH)(2) vitamin D were measured and recalled birth weight recorded.

RESULTS

Fractional intestinal Sr absorption (alpha Sr) was correlated with serum 1,25(OH)(2) vitamin D (p<0.001), but not with 25(OH) vitamin D. Birth weight was inversely associated with serum 1,25(OH)(2) vitamin D (p=0.04), the association being independent of serum calcium, phosphate, creatinine and PTH. Birth weight was inversely correlated with alpha Sr (p=0.03), this association being independent of age, season, customary calcium intake and serum 25(OH) vitamin D; however, when serum 1,25(OH)(2) vitamin D was added into the model, the association became non-significant, suggesting that the association was partially mediated via serum 1,25(OH)(2) vitamin D.

DISCUSSION

We found a significant inverse association between birth weight and intestinal calcium absorption that is partially explained by an association between serum 1,25(OH)(2) vitamin D and birth weight. This suggests a mechanism whereby the intra-uterine environment might affect adult skeletal status.

Osteoporosis in systemic lupus erythematosus: prevention and treatment

The patient with systemic lupus erythematosus (SLE) is at risk of osteoporosis through several factors: the inflammatory disease itself, disease-related co-morbidity, and its treatment. Bone loss is apparent early in the disease and this may be confounded primarily by treatment with corticosteroids. Patients should be assessed for additional risk factors for osteoporosis and general lifestyle measures adopted. Bone mineral density measurement should be considered in SLE patients at high risk of osteoporosis, particularly those starting corticosteroids and in postmenopausal women. Calcium and vitamin D supplementation provide general prophylaxis and are a suitable first-line option. Hormone replacement should be used in hypogondal subjects unless contra-indicated. In subjects at high fracture risk, particularly in postmenopausal women, bisphosphonate therapy should be considered as these agents have been shown to significantly reduce vertebral fracture risk. These measures should reduce the burden of osteoporosis and fracture in patients with lupus.

Birthweight, vitamin D receptor genotype and the programming of osteoporosis

Studies of the association between polymorphisms of the gene for the vitamin D receptor (VDR) and adult bone mass have been inconsistent, pointing to the possibility that gene--environment interactions may vary in different populations. We have demonstrated previously an association between weight in infancy (a marker of the intrauterine and early post-natal environment) and each of adult bone mass and VDR genotype. We therefore sought to extend these observations in an elderly UK cohort and to investigate the possibility of an interaction between these genetic and early environmental markers of later osteoporosis risk. One hundred and sixty-five men and 126 women aged 61--73 years for whom birth records were available underwent bone mass measurements at baseline and follow-up 4 years later. Whole-blood samples were obtained, DNA extracted using standard techniques and polymorphisms in the VDR and collagen type I alpha 1 (Col IA1) genes identified. In the cohort as a whole, there were no significant associations between either birthweight or VDR genotype and bone mineral density (BMD) or bone loss rate at either site. However, the relationship between lumbar spine BMD and VDR genotype varied according to birthweight. Among individuals in the lowest third of birthweight, spine BMD was higher (P = 0.01) in individuals of genotype 'BB' after adjustment for age, sex and weight at baseline. In contrast, spine BMD was reduced (P = 0.04) in individuals of the same genotype who were in the highest third of the birthweight distribution. A significant (P = 0.02) statistical interaction was also found between VDR genotype and birthweight as determinants of BMD. Similar but slightly weaker associations were seen between lumbar spine bone mineral content (BMC) and VDR genotype in the lowest birthweight tertile. When examining the relationship between Col1A1 genotype and bone mass, lumbar spine BMC was higher in individuals of genotype 'Ss' or 'ss' in the lowest birthweight tertile (P = 0.02) after adjustment for age, sex and weight at baseline. These results suggest that genetic influences on adult bone size and mineral density may be modified by undernutrition in utero.

Evidence of association and linkage disequilibrium between a novel polymorphism in the transforming growth factor beta 1 gene and hip bone mineral density: a study of female twins

OBJECTIVE

Bone mineral density (BMD) in later life is a major determinant of osteoporotic fracture risk and has been shown to be under strong genetic influence. Transforming growth factor beta 1 (TGF-beta 1) is an important regulatory cytokine, is found in high concentrations in the bone matrix, and is a plausible candidate for the genetic regulation of BMD.

METHODS

This study investigated whether a novel polymorphism within the TGF-beta 1 gene is associated with BMD in a large normal female population of 1706 dizygotic (DZ) twins (age range 18-76 yr).

RESULTS

A C--->T [corrected] polymorphism was identified in intron 5, the T [corrected] allele having a frequency of 0.25. Subjects homozygous for the presence of the TGF-beta 1 T [corrected] allele had a 4% reduction in femoral neck BMD compared with the other two genotype groups (P<0.025). No effect was seen at the lumbar spine or ultradistal radius, or with calcaneal ultrasound measurements. Results were unaffected after adjustment for potential confounders. These findings were predominantly seen in pre-menopausal subjects, suggesting that this locus has an effect on the attainment of peak BMD. In pre-menopausal women, subjects who were homozygous for the T [corrected] allele had a 5-fold excess risk of having osteoporosis at the femoral neck compared with the other genotype groups. A within-pair analysis using the sibling transmission disequilibrium test confirmed these findings in pre-menopausal women and supported the candidacy of the TGF-beta 1 locus in the genetic regulation of hip BMD.

CONCLUSIONS

These results indicate that allelic variation at the TGF-beta 1 gene contributes to the development of osteoporosis at the hip. The study also highlights the power of candidate gene analysis in twins, in whom loci having modest effects on disease risk can be identified.

Association of polymorphism at the type I collagen (COL1A1) locus with reduced bone mineral density, increased fracture risk, and increased collagen turnover

OBJECTIVE

To examine the relationship between a common polymorphism within intron 1 of the COL1A1 gene and osteoporosis in a nested case-control study.

METHODS

We studied 185 healthy women (mean +/- SD age 54.3+/-4.6 years). Bone mineral density (BMD) was measured using dual x-ray absorptiometry, and fractures were determined radiographically. The COL1A1 genotype was assessed using the polymerase chain reaction and Bal I endonuclease digestion.

RESULTS

Genotype frequencies were similar to those previously observed and in Hardy-Weinberg equilibrium: SS 61.1%, Ss 36.2%, and ss 2.7%. Carriage of at least one copy of the "s" allele was associated with a significant reduction in lumbar spine BMD (P = 0.02) and an increased risk of total fracture (P = 0.04). Urinary pyridinoline levels were significantly elevated in those with the risk allele (P < 0.05).

CONCLUSION

These data support the findings that the COL1A1 gene polymorphism is associated with low BMD and fracture risk, and suggest a possible physiologic effect on total body turnover of type I collagen.

Family history of appendicular fracture and risk of osteoporosis: a population-based study

Family and twin studies demonstrate a strong genetic component to osteoporosis, suggesting that a positive family history for this disease may be an important clinical risk factor. We have therefore explored the extent to which a history of wrist fracture in a female first-degree relative was associated with an increased risk of prevalent fracture at both appendicular and vertebral sites in a cross-sectional study design. One thousand and three Caucasian women (age range 45-64 years) were studied from a UK population cohort. Bone mineral density (BMD) was measured at the lumbar spine and femoral neck using dual-energy X-ray absorptiometry. Appendicular fractures (wrist and hip) were recorded by questionnaire and validated from radiographs and hospital records. Vertebral fractures were assessed using radiologic survey of the thoracolumbar spine and semi-automated morphometric analysis. A positive family history of osteoporotic fracture (hip and/or wrist) in either a mother and/or sister was reported in 138 of the 1003 women. When compared with those with a negative family history of fracture, BMD was significantly reduced in those with a positive history at both the spine (p = 0.02) and the hip (p = 0.02). In total, there were 63 validated fragility fractures found in the 1003 women (16 wrist, 6 hip and 41 vertebral). Family history of osteoporotic fracture was associated with an increased total risk for osteoporotic fracture, with an odds ratio (95% confidence interval) of 2.02 (1.02, 3.78). Site-specific analysis showed that a positive family history of wrist fracture was associated with a considerably elevated risk of wrist fracture, with an odds ratio of 4.24 (1.44, 12.67). These increases in risk remained after adjustment for BMD, suggesting that other genetic factors account for the familial risk of osteoporosis and fracture.

Allelic variation at the interleukin-1 receptor antagonist gene is associated with early postmenopausal bone loss at the spine

Genetic factors play an important role in determining bone mineral density (BMD) in later life, with the genetic influence mediated through effects on both peak mass and on age- and menopause-related bone loss. At menopause there is an increase in the production and activity of various cytokines and growth factors within the bone microenvironment. The activity of interleukin-1 (IL-1), a powerful stimulant of osteoclastic bone resorption, is increased in estrogen-deficient states with increased production of IL-1 and inhibition of the IL-1 receptor antagonist (IL-1ra). Treatment with IL-1ra blocks the bone loss associated with ovariectomy in animals and the IL-1 receptor antagonist gene (IL-1RN) is therefore a potential candidate gene for the regulation of postmenopausal bone loss. We examined the relationship between annual rates of change in BMD over 5 years and an 86 bp variable number tandem-repeat polymorphism of the IL-1RN gene in 108 early postmenopausal women. All women were within 5 years of a natural menopause at the study's onset, healthy, and not on hormone replacement therapy or other medication known to affect bone metabolism. BMD was measured annually over the 5 year study period at the lumbar spine and femoral neck using dual-energy X-ray absorptiometry. Three alleles were identified (A1 = 4 repeats, A2 = 2 repeats, A3 = 5 repeats), with five genotypes observed: A1A1 (41.7%), A1A2 (45.4%), A2A2 (6.5%), A1A3 (2.8%), and A2A3 (3.7%). For analysis, alleles were collapsed into a biallelic system grouping the A1 and A3 alleles. There was no significant relationship between the IL-1RN genotypes and baseline bone mass at either the spine or hip. IL-1RN genotype was significantly associated with annual rates of change in spinal bone mass (p < 0.05), and this finding remained significant after adjustment for age, weight, and baseline BMD. Carriage of at least one copy of the A2 allele was associated with reduced bone loss at the spine (mean change in BMD +/- SD: -0.81 +/- 1.46%/year) when compared with noncarriage of the A2 allele (mean change -1.38 +/- 1.48%/year), p = 0.05. We therefore conclude that allelic variation at the IL-1RN locus is associated with differential rates of early postmenopausal bone loss at the spine. Further research will be required to clarify the mechanisms underlying these findings and to determine whether this association translates into a significant long-term effect on BMD and fracture in later life.

Effects of cyclical etidronate combined with calcitriol versus cyclical etidronate alone on spine and femoral neck bone mineral density in postmenopausal osteoporotic women

OBJECTIVES

Few data are available on the effects of combination therapy for the treatment of osteoporosis. The aim of this study was to compare the effects of intermittent cyclical etidronate (E) therapy alone with a combination of cyclical etidronate and calcitriol (E + C) on spine and femoral neck bone mineral density (BMD) at one year.

METHODS

Postmenopausal women with at least one non-traumatic vertebral fracture or z score < -1.5 were randomly allocated to an E group (each cycle = oral etidronate 400 mg daily for 14 days followed by calcium 500 mg daily for 76 days) or an E + C group (as for E plus oral calcitriol 0.5 microgram daily). Lumbar spine and femoral neck BMDs were measured by dual energy x ray absorptiometry at baseline and at one year. The study design did not contain a placebo group.

RESULTS

The mean % increase in lumbar spine BMD was 5.2% (95% CI = 3.4 to 7.0) in the E + C group (n = 24), which was significantly greater than the 2.7% (95% CI = 1.3 to 4.1) increase in the E group (n = 23) (p < 0.05). The femoral neck BMD in the E + C group increased by 2.0% (95% CI = 0.8 to 3.2), which was significantly different from the E group where there was a -0.4% (95% CI = -2.4 to 1.6) change (p = 0.046).

CONCLUSIONS

These data show that a combination of cyclical etidronate and calcitriol is better than cyclical etidronate alone in terms of changes in BMD at both spine and femoral neck sites. Although further data are needed on fracture efficacy, this study suggests that combination therapies have additive therapeutic potential that may exceed that expected from their theoretical mode of action.

Genetic factors in osteoporosis. What are the implications for prevention and treatment?

Osteoporosis is a common disease that affects 1 in 3 women. Family and twin studies have demonstrated that there is a strong genetic component to this condition. Potential candidate genes examined for their regulatory effect on bone mass include those for collagen type I, estrogen and vitamin D receptors, and various cytokines and growth factors. To date, most work has focused on the vitamin D receptor (VDR) gene, and experience with this locus will probably act as a model for many future studies. There is increasing evidence, from population studies that have examined the relationship between VDR genotype and bone mineral density, of genetic heterogeneity and gene-environment interactions. Response to therapeutic agents may also be affected by an individual's underlying genotype, partly explaining the range of responses that are commonly observed in clinical practice. Knowledge of a person's genotype could, therefore, allow current therapies to be targeted to those most likely to benefit, with a possible reduction in adverse effects. Largescale genomic studies of osteoporosis may also identify novel genes, and this may lead to both a better understanding of disease pathophysiology and to the discovery of potential targets for drug development.

Association of early osteoarthritis of the knee with a Taq I polymorphism of the vitamin D receptor gene

OBJECTIVE

To determine whether a polymorphism of the vitamin D receptor (VDR) gene, already associated with osteoporosis, might also relate to the risk of osteoarthritis (OA).

METHODS

A population cohort of 351 postmenopausal women (ages 45-64 years) was studied using anteroposterior radiographs of the knee, which were graded for OA according to the Kellgren and Lawrence classification system. The VDR genotype was determined by using polymerase chain reaction and by digestion with the restriction enzyme Taq I.

RESULTS

The VDR allele "T" was associated with an increased risk of knee OA compared with the "t" allele, with an odds ratio of 2.82 (95% confidence interval 1.16-6.85; P = 0.02). A dominant pattern of risk was suggested. The frequency of the VDR genotype differed significantly between OA cases and controls (P = 0.03 by Fisher's exact test).

CONCLUSION

A Taq I polymorphism of the VDR gene appears to be associated with an increased risk of knee OA. This is the first genetic locus that has been shown to influence the risk of early knee OA within the general population.

Polymorphisms of the vitamin D receptor, infant growth, and adult bone mass

Family and twin studies have demonstrated a strong genetic component to the development of peak bone mass. Early fetal and infant environment has also been shown to influence bone mass through an effect on skeletal size and mineral content. We report a retrospective study that has examined whether early infant growth is regulated by genetic factors shown to be associated with bone mass. We have determined the vitamin D receptor (VDR) gene alleles for 66 women (mean age 65.5 years) on whom detailed birth records were available. There was a statistically significant trend (P = 0.04) for VDR genotype against weight at the age of 1 year, with the "tt" homozygote group having 7% higher weight. We conclude that early fetal or infant environment may interact with an individual's underlying genotype to program early skeletal growth, and that this may track through later life to influence adult characteristics. Further prospective studies are required, however, to fully clarify the precise environmental and genetic mechanisms underlying these findings.

Alendronate: a new bisphosphonate for the treatment of osteoporosis

Alendronate is a drug with considerable potential. It is likely to work best in elderly patients with moderate to severe osteoporosis. Long-term studies and comparison with other therapeutic agents are needed before its exact role is established.

Polymorphisms of the vitamin D receptor gene do not predict quantitative ultrasound of the calcaneus or hip axis length

Quantitative ultrasound of the calcaneus and hip axis length are independent predictors of hip fracture and have a major genetic component. Polymorphisms of the vitamin D receptor gene (VDR) have been associated with variations in bone density in a number of studies. The aim of this study was to examine the role of VDR on other parameters associated with the risk of fracture. One hundred and eighty-nine pairs of healthy female dizygous twins were genotyped and had calcaneal ultrasound (broadband ultrasound attenuation and velocity of sound) and hip axis length measurements performed. Twin analysis using intraclass correlation coefficients and intrapair differences failed to find an association between the VDR polymorphisms and hip axis length or calcaneal ultrasound. Analysing the twins as a population, irrespective of twinning, also failed to find any association. The search for alternative genes influencing bone fragility should continue as a research priority.

Can biochemical markers predict bone loss at the hip and spine?: a 4-year prospective study of 141 early postmenopausal women

A number of recent studies have suggested that non-invasive measures of bone turnover are associated with bone loss at the forearm in postmenopausal women. Whether bone turnover markers are predictive of bone loss from the clinically important sites of lumbar spine and femoral neck remain unclear, and was the aim of this 4-year prospective study. One hundred and forty-one normal, postmenopausal women (mean age 52.0 +/- 3.3 years, mean menopause duration 20.4 +/- 5.7 months) were recruited for the study in 1988. Fasting early morning samples of blood and urine were collected at the baseline visit and stored at -20 degrees C prior to analysis. Serum was assayed for osteocalcin, oestradiol, oestrone, oestrone sulphate, testosterone, sex hormone binding globulin, dehydroepiandrosterone sulphate and total alkaline phosphatase. Urine was assayed for calcium, hydroxyproline, oestrone glucuronide and the collagen cross-links pyridinoline and deoxypyridinoline using high-performance liquid chromatography. Bone density was measured at the lumbar spine and femoral neck using dual photon absorptiometry at time 0, 12, 24 and 48 months. The mean annual percentage change in bone density (SE) was -1.41% (0.18) at the lumbar spine and -0.86% (0.22) at the femoral neck. There was no evidence of bimodality or a fast loser subgroup as the rates of change were normally distributed. Both simple and multiple stepwise regression analyses revealed no significant correlation between the rates of change in bone density with any biochemical marker, either individually or in combination, despite the study having sufficient power (80%) to detect a correlation of 0.5 between any biochemical marker levels and bone loss. We conclude that single measurements of these markers of bone turnover and endogenous sex hormones appear unlikely to be clinically useful in predicting early postmenopausal bone loss from either the spine or the hip.

Influence of vitamin D receptor genotype on bone mineral density in postmenopausal women: a twin study in Britain

OBJECTIVES

To investigate the possible association between vitamin D receptor genotype and bone mineral density in a large group of postmenopausal twins.

DESIGN

Cross sectional twin study.

SETTING

Twin population based in Britain.

SUBJECTS

95 dizygotic (non-identical) pairs of twins and 87 monozygotic (identical) pairs of twins aged 50-69 years, postmenopausal, and free of diseases affecting bone, recruited from a national register of twins and with a media campaign.

MAIN OUTCOME MEASURES

Bone mineral density measured at the hip, lumbar spine, forearm, and for the whole body by dual energy x ray absorptiometry in relation to differences in the vitamin D receptor genotype.

RESULTS

At all sites the values of bone density among dizygotic twins were more similar in those of the same vitamin D receptor genotype than in those of differing genotype, and the values in the former were closer to the correlations seen in monozygotic twins. Women with the genotype that made them at risk of osteoporotic fracture had an adjusted bone mineral density that was significantly lower by SD 0.5 to 0.6 at the hip, lumbar spine, and for the whole body. The results could not be explained by differences in age, weight, years since menopause, or use of hormone replacement therapy.

CONCLUSIONS

The findings that in postmenopausal women in Britain bone density-particularly at the hip and spine-is genetically linked and specifically associated with the vitamin D receptor genotypes should lead to novel approaches to the prevention and treatment of osteoporosis.

Indian herbal remedies for diabetes as a cause of lead poisoning

Herbal remedies from the Indian subcontinent have been found to have high concentrations of heavy metals and unsupervised treatment may result in toxicity. We report the case of an Indian patient with hepatitis who was found to have lead poisoning where the source was traced to ethnic remedies he had been taking for diabetes.