Effect of immobilization on vitamin D status and bone mass in chronically hospitalized disabled stroke patients

Molecular insights into the pathogenic impact of vitamin D deficiency in neurological disorders

Neurological disorders are the major cause of disability, leading to a decrease in quality of life by impairing cognitive, sensorimotor, and motor functioning. Several factors have been proposed in the pathogenesis of neurobehavioral changes, including nutritional, environmental, and genetic predisposition. Vitamin D (VD) is an environmental and nutritional factor that is widely distributed in the central nervous system's subcortical grey matter, neurons of the substantia nigra, hippocampus, thalamus, and hypothalamus. It is implicated in the regulation of several brain functions by preserving neuronal structures. It is a hormone rather than a nutritional vitamin that exerts a regulatory role in the pathophysiology of several neurological disorders, including Alzheimer's disease, Parkinson's disease, epilepsy, and multiple sclerosis. A growing body of epidemiological evidence suggests that VD is critical in neuronal development and shows neuroprotective effects by influencing the production and release of neurotrophins, antioxidants, immunomodulatory, regulation of intracellular calcium balance, and direct effect on the growth and differentiation of nerve cells. This review provides up-to-date and comprehensive information on vitamin D deficiency, risk factors, and clinical and preclinical evidence on its relationship with neurological disorders. Furthermore, this review provides mechanistic insight into the implications of vitamin D and its deficiency on the pathogenesis of neurological disorders. Thus, an understanding of the crucial role of vitamin D in the neurobiology of neurodegenerative disorders can assist in the better management of vitamin D-deficient individuals.

What is the Current Role for Vitamin D and the Risk of Stroke?

INTRODUCTION

Increasing evidence supports the relationship between vitamin D and stroke. Vitamin D has now been proposed as a prognostic biomarker also for functional outcome in stroke patients.

METHODS

A revision of the data suggests that low vitamin D is associated more with ischemic than with haemorrhagic stroke, even if the role of optimal vitamin D levels for vascular wall is still unclear. Vitamin D deficiency induces with different mechanisms an alteration of vascular wall.

RESULTS

However, to date, the research supporting the effectiveness of vitamin D supplementation in stroke and in post-stroke recovery is still inadequate and conclusive evidences have not been published.

CONCLUSION

In this review, we provide a better understanding of the role of vitamin D in stroke.

Decrement of Serum Vitamin D Level After Stroke

Objective

To investigate the serum vitamin D level and its determinant factors in stroke patients.

Methods

Fifty-one stroke patients who had documented serum level of 25-hydroxyvitamin D(25(OH)D) were included. Patients were divided into subacute (n=23) and chronic groups (n=28). The mean levels of 25(OH)D of the two groups were compared. Correlations between each 25(OH)D level and post-stroke duration were also analyzed. To assess other possible influencing factors, patients were subdivided by ambulation ability and feeding methods for comparison of 25(OH)D level.

Results

The mean level of 25(OH)D was significantly lower in the chronic group than in the subacute group (12.3 vs. 16.3 ng/mL; p<0.05). The serum 25(OH)D level decreased according to the duration after stroke (r=−0.52, p=0.01). Patients with a history of total parenteral nutrition had lower 25(OH)D levels than subjects who had enteral nutrition in the subacute group (7.3 vs. 18.8 ng/mL; p<0.01). However, the levels of 25(OH)D were not different between the oral feeding and tube feeding groups. Among the chronic group subjects, patients who could walk without assistance had higher 25(OH)D levels than non-ambulatory patients (ambulatory vs. non-ambulatory group; 18.3 vs. 11.3 ng/mL; p<0.05).

Conclusion

After stroke onset, serum vitamin D level decreases with time regardless of feeding methods, and total parenteral nutrition may aggravate its deficiency. In terms of long-term care, non-ambulatory patients might be at a higher risk of vitamin D deficiency. Supplementation of vitamin D should be considered especially for stroke patients who are non-ambulatory and on total parenteral nutrition.

Prevalence of and risk factors for osteoporosis in adults with acquired brain injury

BACKGROUND

Low bone mineral density (BMD) is common in older people with stroke, particularly in the paretic limb. Younger people with acquired brain injury (ABI), of all causes, are at increased risk of low BMD.

AIMS

To examine prevalence of low BMD, based on World Health Organisation diagnostic criteria, in patients with ABI.

METHODS

This is a cross-sectional study of 112 ABI patients. All completed a questionnaire, had laboratory investigations and DXA assessment of lumbar spine and one or both hips.

RESULTS

Mean age ± SD of participants was 45.7 ± 13.7 years. Risk of vitamin D deficiency (25-OHD < 30 nmol/L) occurred in 27.7 %, 34.3 % had adequate levels (30-50 nmol/L) and 36.6 % had levels in excess of this. Based on T-scores, 41.1 % had osteopenia and 21.4 % had osteoporosis. A Z score of -1 or less but greater than -2 occurred in 25 %; a further 21.4 % had a Z score of -2 or less. Patients who could walk outdoors had significantly higher BMD at the neck of femur than those who walked indoors only and those who could not walk at all (p < 0.001). On multiple linear regression analysis, ambulatory ability and duration of disability were independent predictors of BMD at sound neck of femur and total proximal femur.

CONCLUSIONS

Osteopenia and osteoporosis are common in young adults with ABI compared with the general population. Bone heath monitoring should form part of the long-term follow-up of this patient group.

Bone mineral density and incidence of stroke: European prospective investigation into cancer-norfolk population-based study, systematic review, and meta-analysis

BACKGROUND AND PURPOSE

The prospective link between osteoporosis and future risk of stroke requires evidence from large-scale population-based long-term studies.

METHODS

Calcaneum broadband ultrasound attenuation was measured in the Norfolk cohort of the European Prospective Investigation into Cancer-Norfolk between 1997 and 2000. Incident strokes were ascertained by hospital record linkage and death certificates in March 2009 and December 2011, respectively. A search of MEDLINE and EMBASE was performed to evaluate the relationship between bone mineral density and incident stroke. After data extraction of relevant studies, pooled risk of stroke was estimated using meta-analysis.

RESULTS

In 14 290 participants (mean follow-up of 9.3 years; total person-years 132 574), there were 599 incident strokes. Participants in the lowest 10% of the calcaneum broadband ultrasound attenuation distribution had an increased stroke risk (hazard ratio 1.41; 95% confidence intervals, 1.02-1.94) compared with those in the top 30% of the distribution after adjustments. A decrease of ~1 standard deviation in broadband ultrasound attenuation (20 db/MHz) was associated with a 17% increase in relative risk of stroke (95% confidence intervals, 5%-30%). Meta-analysis of 4 studies (25 760 participants, 1237 cases of stroke) found that for every decrease in 1 standard deviation in bone mineral density, there was an increased risk of incident stroke among women (pooled relative risk 1.22; 95% confidence intervals, 1.09-1.37; I2=0%, 3 studies) but not in men (pooled relative risk 1.05; 95% confidence intervals, 0.94-1.17; I(2)=0%, 2 studies).

CONCLUSIONS

Bone mineral density predicts total stroke risk. The evidence is stronger in women with regard to the continuous relationship.

Denosumab for treatment of immobilization-related hypercalcaemia in a patient with advanced renal failure

We describe the case of a young adult with immobilization-related hypercalcaemia and advanced renal insufficiency. Because of the uncertain safety profile of bisphosphonates in such patients, only a low dose of pamidronate was administered twice. This did not result in a sufficient decrease in the serum calcium concentration nor was the decrease sustained. We decided to administer a single dose of denosumab, a monoclonal antibody against the receptor activator of nuclear factor-κB ligand, a new antiresorptive agent registered for use in osteoporosis. This resulted in rapid and sustained decrease in the serum calcium concentration. Transient hypocalcaemia ensued with normalization after vitamin D supplementation. Furthermore, we summarize what is known about hypercalcaemia caused by immobilization.

Bone mineral density in adults disabled through acquired neurological conditions: a review

This article is a review of the changes in bone mineral density (BMD), which occur in a number of acquired neurological conditions resulting in disability. For each of spinal cord injury, stroke, multiple sclerosis, Parkinson's disease, and traumatic brain injury, the following aspects are discussed, where information is available: prevalence of low BMD according to World Health Organization diagnostic categories and recommended diagnostic method, prevalence based on other diagnostic tools, comparison of BMD with a control population, rate of decline of BMD following onset of the neurological condition, factors influencing decline; mechanism of bone loss, and fracture rates. The common risk factors of immobilization and vitamin D deficiency would appear to cross all disability groups, with the most rapid phase of bone loss occurring in the acute and subacute phases of each condition.

Bone loss with multiple sclerosis: effect of glucocorticoid use and functional status

BACKGROUND

Emerging data suggest a significantly increased prevalence of low bone mineral density (BMD) in men and women with multiple sclerosis (MS) compared to age matched controls. This study was performed to evaluate bone mineral mass in patients with MS in comparison to healthy age-and sex matched controls and to determine association of glucocorticoid use or ambulation ability with changing in bone mass in these individuals.

METHODS

Eighty two patients with MS and 328 age-sex matched healthy controls participated in the study. The Kurtzke expanded disability status scale (EDSS) was used to evaluate disability and functional capacity. Bone mineral density was measured using Dual X-ray absorptiometry. Serum calcium, phosphorus and 25(OH) vitamin D levels were assessed.

RESULTS

The MS patients had significantly lower BMD at the lumbar spines, neck and total femur compared to age-sex matched controls. EDSS scores were inversely correlated with total femur and spinal BMD. There was a negative correlation with cumulative steroid dose and BMD only for femoral neck.

CONCLUSION

BMD was significantly lower in MS patients. Decreased ambulatory status and glucocorticoid usage were associated with low BMD in MS patients. These patients should be encouraged to increase mobility and to have protective measures to maintain bone mass.

RETRACTED: Beneficial effect of etidronate therapy in chronically hospitalized, disabled patients with stroke

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editor-in-Chief due to data fabrication, systematic authorship misconduct, text duplication, concerns about data integrity, and scientific misconduct. In addition, several publications reporting non-randomized research by members of this group of investigators have been retracted.

Role of vitamin D in adults requiring nutrition support

The major and most well-known function of vitamin D is to maintain calcium and phosphorus homeostasis and promote bone mineralization. However, recent evidence suggests that vitamin D may be important for a variety of nonskeletal outcomes. The review synthesizes the available evidence for the role of vitamin D in skeletal health as well as its novel roles in medical conditions such as muscle function, falls, immunity, glucose homeostasis, and cardiovascular diseases. The article reviews methods for assessing vitamin D status and suggests strategies to restore vitamin D status in patients requiring enteral or parenteral nutrition who are at particularly high risk of hypovitaminosis D. Screening for hypovitaminosis D with plasma total 25-hydroxyvitamin D should be a routine part of the care of the patient requiring enteral or parenteral nutrition. Restoration of optimal vitamin D status with high-dose supplemental vitamin D is required in most cases, whereas exposure to sunlight or an ultraviolet B radiation-emitting device is most effective in patients with severe malabsorption or those requiring long-term parenteral therapy. Given the emerging role of vitamin D for a variety of acute and chronic conditions, the optimal vitamin D status in acutely ill patients as well as in patients requiring long-term nutrition therapy warrants further investigation.

Can early onset bone loss be effectively managed in post-stroke patients? An integrative review of the evidence

BACKGROUND

bone loss post-stroke can lead to an increased risk of fracture. Fractures compound the effects of a stroke, resulting in greater dependency for the individual and an increased burden for health and social care.

OBJECTIVES

to identify risk factors for bone loss post-stroke and appraise bone loss or fracture risk reduction interventions. To develop a research agenda that informs the design and development of risk reduction strategies.

DESIGN

an integrative review.

METHODS

the search strategies used in Medline, Embase, AMED and CINAHL from 1966 to July 2006 identified 530 records. Ninety-nine papers with a focus on risk factors or interventions to prevent bone loss or fractures post-stroke were identified. Hand searching and scoping grey literature produced 59 additional papers. Data analysis, including data reduction and data display using matrices, enabled patterns and themes to be derived from differing study designs.

RESULTS

risk factors for bone loss post-stroke are reduced mobility, vitamin D deficiency, gender and time since stroke. Early mobilisation post-stroke may reduce bone loss, and so avoid fractures, but evidence is needed. Providing vitamin D supplements and Bisphosphonates in post-stroke patients tends to reduce bone loss, but larger treatment trials are required.

CONCLUSIONS

the evidence base for bone loss management post-stroke is limited. Large, prospective, multi-centre, longitudinal studies are needed to clarify optimum treatments to reduce post-stroke bone loss, and test the effects on clinical outcomes. A 'skeletal health' checklist to aid implementation of treatments within stroke rehabilitation has been suggested but not yet developed.

Responses of parathyroid hormone to vitamin D supplementation: a systematic review of clinical trials

The beneficial bone effects of vitamin D supplementation have been attributed to suppression of secondary hyperparathyroidism by 25-hydroxyvitamin D (25-OHD) levels at least 50nmol/l. In this systematic review, we have analyzed the results of 52 clinical trials, including 72 intervention groups and 6290 patients, on vitamin D supplementation in order to evaluate the experimental evidence and the effects of age and chronic immobility on responses of parathyroid hormone (PTH). The papers for this systematic review were selected through a search in PubMed and through a review of the reference lists of articles. Negative logarithmic (R(2)=0.318, p<0.001) and linear (R(2)=0.294, p<0.001) correlations were found between 25-OHD and PTH levels, when all pre- and post-trial values were scattered. Negative linear (R(2)=0.385, p<0.001) and logarithmic (R(2)=0.406, p<0.001) correlations were also found between the changes in 25-OHD and PTH levels. Age correlated negatively with changes in PTH (r=-0.476, p<0.001). The vitamin D supplementation of the chronically immobile patients resulted in a smaller decrease in PTH levels (-8.4 vs. -17.4%, p<0.001) despite a larger increase in 25-OHD levels (187.2% vs. 109.8%, p<0.001). According to the multiple regression analysis the changes in PTH were independently predicted by pre-trial PTH, changes in 25-OHD, age and chronic immobility, explaining 53.2% (R(2)=0.532) of the variation. This meta-analysis shows that responses of PTH to vitamin D supplementation are not only determined by the baseline PTH levels and changes in vitamin D status, but also by age and mobility of the patients. Our results also suggest that PTH decreases quite linearly during vitamin D supplementation at any given 25-OHD level. Longitudinal vitamin D supplementation studies on populations with wide range of mobility and age are needed to further elucidate their confounding effects. In determining the sufficient doses of vitamin D supplementation and adequate 25-OHD levels, these confounding effects and the inter-individual variation in responses of PTH to vitamin D supplementation should be taken into account.

Vitamin D supplementation has minor effects on parathyroid hormone and bone turnover markers in vitamin D-deficient bedridden older patients

OBJECTIVES

to evaluate the effects of vitamin D supplementation on parathyroid function and bone turnover in aged, chronically immobile patients.

DESIGN

a randomised double-blind controlled trial.

SUBJECTS

two hundred and eighteen long-term inpatients aged over 65 years.

INTERVENTION

the patients were randomised into treatment groups of I-III, each receiving 0 IU, 400 IU and 1200 IU cholecalciferol per day, respectively. In case of inadequate consumption of dairy products, patients received a daily calcium substitution of 500 mg.

MEASUREMENTS

plasma concentrations of 25-hydroxyvitamin D (25-OHD), intact parathyroid hormone (PTH), amino-terminal propeptide of type I procollagen (PINP), a marker of bone formation, and carboxy-terminal telopeptide of type I collagen (ICTP), a marker of bone resorption, were measured at baseline and after 6 months.

RESULTS

the patients (age 84.5 years) were chronically bedridden. The baseline 25-OHD was low (23 nmol/l), correlated inversely with PINP, and tended to associate inversely with PTH. The prevalence of vitamin D deficiency (VDD) (25-OHD < 50 nmol/l) was 98% and PTH was elevated in 23% of the patients. Vitamin D supplementation significantly increased 25-OHD concentrations (124% group II, 204% group III) and decreased PTH (-7% group II, -8% group III). PINP tended to decrease, but ICTP tended to increase, and only their ratio decreased significantly. The tendency of ICTP to increase was inconsistent. Changes in 25-OHD correlated inversely with those in PTH and PINP.

CONCLUSIONS

vitamin D supplementation has minor effects on PTH and bone turnover in chronically immobilised aged patients with VDD. Further comparative studies and meta-analyses are warranted to elucidate the confounding effects of different mobility levels on the benefits of vitamin D supplementation in patients with differing baseline PTH levels.

Rapid long-term bone loss following stroke in a man with osteoporosis and atherosclerosis

Bone loss in humans has been reported where there is reduced mechanical loading such as in space flight, spinal cord injury, and stroke. Whether osteoporotic patients are susceptible to further bone loss in states of underloading such as hemiparesis is unknown. Here we report the case of a 64-year-old man with established idiopathic osteoporosis and atherosclerosis who presented with a right middle cerebral artery territory stroke. Annual bone mineral density measurements were made at the left hip and spine before and after left hemiparesis. The left total hip T-score was -3.2 before the stroke. Following stroke, there was rapid and sustained bone loss with a reduction in bone mineral density (BMD) of 21.6% over 3 years despite oral bisphosphonate therapy. There was also an unexpected decline in vertebral BMD after the stroke. This is the first report of the accelerated effect of hemiplegia on bone loss in an already osteoporotic skeleton.

Vitamin D deficiency and reduced bone mineral density in multiple sclerosis: effect of ambulatory status and functional capacity

Multiple sclerosis (MS) is a chronic disease and a major cause of disability in young adults. The aims of this study were to assess bone mass in patients with MS in comparison to healthy age- and sex-matched controls, and to evaluate factors influencing bone mineral density (BMD), and the relationship of the pain threshold at peripheral and axial sites with BMD in MS. Thirty-one patients with MS and 30 matched healthy controls participated in the study. The Kurtzke expanded disability status scale (EDSS) and the functional independence measure (FIM) were used to scale disability, mobility, and functional status. Serum 25(OH) vitamin D levels were measured. BMD was measured using dual X-ray absorptiometry (DXA). MS patients had significantly lower BMD at the lumbar spine (L2-L4) and femur trochanter compared to the matched controls. BMD of the lumbar spine was nearly 1 SD lower in MS patients compared with the healthy reference population (Z scores). MS patients had significantly lower vitamin D levels (17.3 ng/ml vs 43.1 ng/ml; P < 0.001) compared to controls, and 19 patients (61%) had a serum level of vitamin D that was less than 20 ng/ml. EDSS scores in the patients were inversely correlated with proximal femur BMD but not with spinal BMD. There was a negative correlation with the cumulative steroid dose and BMD only for femur trochanter BMD. Total myalgia scores for paravertebral muscles correlated significantly with spinal BMD. In conclusion, BMD is significantly lower in MS patients than in healthy controls, vitamin D deficiency is prevalent in MS, and ambulatory status is a determinative factor for osteoporosis in MS. Patients should be encouraged to have adequate sunlight exposure and to increase their mobility. Specific strengthening exercises for hip and back muscles in MS patients would have a substantial impact on bone density, osteoporosis, fracture risk, and mobility.

Increased Bone Resorption in the Proximal Femur in Patients with Hemiplegia

OBJECTIVES

To investigate the relationship between the proximal femoral bone mineral density and bone resorption markers, determinants of calcium metabolism and vitamin D levels in elderly stroke patients.

DESIGN

A total of 80 patients and 20 controls were enrolled in the study. Bone mineral density measurements were obtained at the proximal femur. In all subjects, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, intact parathyroid hormone, osteocalcin, deoxypyridinoline, and ionized calcium concentrations were measured. Barthel Index and Motricity Index Leg Score were recorded all patients.

RESULTS

The serum concentrations of deoxypyridinoline, intact parathyroid hormone, and the mean serum ionized calcium levels were significantly higher in patients with stroke than that of the control subjects. The mean serum 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D concentrations in patients were significantly lower than those of the control group (P < 0.05). The bone mineral density of proximal femurs of paretic limbs was decreased significantly compared with those of the control group (P < 0.05). There were significant correlations between the Z score of the hemiplegic side and the patients' Barthel Index, Motricity Index Leg Score, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, calcium, and deoxypyridinoline.

CONCLUSIONS

This study provides clear evidence that decreased mobility, vitamin D status, and bone turnover variables in patients after stroke are important factors in the greater bone loss in the paretic leg.

Abnormal calcium homeostasis in disabled stroke patients with low 25-hydroxyvitamin D

Disabled elderly stroke patients occasionally have very low serum 25-hydroxyvitamin D (25-OHD), which may be due to sunlight deprivation and malnutrition. Many of such patients have very low level of serum 1, 25-dihydroxyvitamin D (1, 25-[OH]2D; calcitriol), and immobilization-induced hypercalcemia may be responsible for inhibition of renal synthesis of calcitriol. To elucidate determinants of serum 1, 25-[OH]2D levels in elderly poststroke patients, we measured serum indices of bone and calcium metabolism and metacarpal bone mineral density (BMD). Patients whose serum 1, 25-[OH]2D concentration was below the mean-3 SD of normal control subjects were defined as the low 1, 25-[OH]2D group and the rest of the patients were designated as the normal group. Mean illness duration was 59 months in the normal group and 20 months in the low group. The Barthel index (BI), which predicts the degree of immobilization, was significantly lower in the low group than in the normal group. Mean serum 1, 25-[OH]2D and 25-OHD concentrations in the normal group were 36.7 pg/ml and 4.4 ng/ml, respectively; and those in the low group were 14.2 pg/ml and 1.8 ng/ml, respectively. Multiple regression analysis identified illness duration and calcium level as independent determinants of 1, 25-[OH]2D in both groups, and PTH in the normal group and 25-OHD in the low group were additional independent determinants. BMD in stroke patients was significantly lower than that in controls, and BMD in the normal group was lower as compared to the low group. BMD correlated negatively with 1, 25-[OH]2D and PTH in the normal group, and hyperparathyroidism may contribute to reduced BMD. These results suggest that treatment of decreased bone mass in stroke patients has to be individualized according to vitamin D status and calcium homeostasis.

Amelioration of osteoporosis by menatetrenone in elderly female Parkinson's disease patients with vitamin D deficiency

Significant reduction in bone mineral density (BMD) occurs in patients with Parkinson's disease (PD), correlating with immobilization and with vitamin D deficiency, and increasing the risk of hip fracture, especially in elderly women. As a biological indicator of compromised vitamin K status, an increased serum concentration of undercarboxylated osteocalcin (Oc) has been associated with reduced BMD in the hip and an increased risk of fracture in otherwise healthy elderly women. We evaluated treatment with vitamin K(2) (menatetrenone; MK-4) in maintaining BMD and reducing the incidence of nonvertebral fractures in elderly female patients with PD. In a random and prospective study of PD patients, 60 received 45 mg of MK-4 daily for 12 months, and the remaining 60 (untreated group) did not. At baseline, patients of both groups showed vitamin D and K(1) deficiencies, high serum levels of ionized calcium, and glutaminic residue (Glu) Oc, and low levels of parathyroid hormone (PTH) and 1,25-dihydroxyvitamin D [1,25-(OH)(2)D], indicating that immobilization-induced hypercalcemia inhibits renal synthesis of 1,25-(OH)(2)D and compensatory PTH secretion. BMD in the second metacarpals increased by 0.9% in the treated group and decreased by 4.3% in the untreated group (p < 0.0001). Vitamin K(2) level increased by 259.8% in the treated group. Correspondingly, significant decreases in Glu Oc and calcium were observed in the treated group, in association with an increase in both PTH and 1,25-(OH)(2)D. Ten patients sustained fractures (eight at the hip and two at other sites) in the untreated group, and one hip fracture occurred among treated patients (p = 0.0082; odds ratio = 11.5). The treatment with MK-4 can increase the BMD of vitamin D- and K-deficient bone by increasing vitamin K concentration, and it can also decrease calcium levels through inhibition of bone resorption, resulting in an increase in 1,25-(OH)(2)D concentration.

Falls, fractures, and osteoporosis after stroke: time to think about protection?

BACKGROUND

Osteoporosis is a significant complication of stroke. The clinical course of hemiplegic stroke predisposes patients to disturbed bone physiology. Sudden immobility and unilateral loss of function unload the skeleton at key areas such as the affected hip. This is manifest by an early reduction in bone density at this site. Stroke patients may also have motor, sensory, and visual/perceptual deficits that predispose them to falls. These factors result in an early but sustained increase in hip fractures after stroke.

SUMMARY OF COMMENT

Potential bone loss is often overlooked in stroke treatment. Morbidity and mortality from hip fractures might be reduced by preventing bone loss at an early stage. In the crucial first year after stroke, bone loss seems to be due to accelerated resorption. Bisphosphonates are the drugs of choice in preventing osteoclastic bone resorption, but oral administration soon after stroke may be impractical. Potent new intravenous bisphosphonates have been used in postmenopausal women with osteoporosis with good preliminary results. Effective dosing regimens for osteoporosis have included a single annual or semiannual injection of bisphosphonate as well as weekly oral dosing. This article reviews the current literature on osteoporosis and hip fractures after stroke, making a case for a trial of intravenous bisphosphonates early after stroke.

CONCLUSIONS

Hip fracture after stroke is an increasingly recognized problem. Measures to prevent bone loss and preserve bone architecture have not been part of stroke management thus far. Because rapid bone loss is a risk factor for fracture, we believe that a randomized, placebo-controlled trial of intravenous bisphosphonates given in the early phase of stroke rehabilitation is indicated.

Vitamin D deficiency and risk of hip fractures among disabled elderly stroke patients

BACKGROUND AND PURPOSE

Risk of hip fracture after stroke is 2 to 4 times that in a reference population. Osteomalacia is present in some patients with hip fractures in the absence of stroke, while disabled elderly stroke patients occasionally have severe deficiency in serum concentrations of 25-hydroxyvitamin D (25-OHD) (</=5 ng/mL). To determine the effects of vitamin D status on hip fracture risk, we prospectively studied a cohort of patients with hemiplegia after stroke who were aged at least 65 years.

METHODS

We compared baseline serum indices of bone metabolism, bone mineral density, and hip fracture occurrence in stroke patients with serum 25-OHD </=25 nmol/L (</=10 ng/mL; deficient group, n=88) with findings in patients from the same cohort who had 25-OHD levels 26 to 50 nmol/L (10 to 20 ng/mL; insufficient group, n=76) or >/=51 nmol/L (>/=21 ng/mL; sufficient group, n=72).

RESULTS

Over a 2-year follow-up interval, hip fractures on the paretic side occurred in 7 patients in the deficient group and 1 patient in the insufficient group (P<0.05; hazard ratio=6.5), while no hip fractures occurred in the sufficient group. The 7 hip fracture patients in the deficient group had an osteomalacic 25-OHD level of <5 ng/mL. Higher age and severe immobilization were noted in the deficient group. Serum 25-OHD levels correlated positively with age, Barthel Index, and serum parathyroid hormone.

CONCLUSIONS

Elderly disabled stroke patients with serum 25-OHD concentrations </=12 nmol/L (</=5 ng/mL) have an increased risk of hip fracture. Immobilization and advanced age cause severe 25-OHD deficiency and consequent reduction of BMD.

Abnormal bone and calcium metabolism in patients after stroke

OBJECTIVE

To review how mineral stores and endocrine factors affect bone mass in poststroke patients immobilized by hemiparesis.

DATA SOURCES

Computer databases and published indexes.

STUDY SELECTION

Case-control studies of hemiparetic poststroke patients examined regarding bone metabolism.

DATA EXTRACTION

References were obtained from MEDLINE; all data concerning the objective were used.

DATA SYNTHESIS

Bone loss occurs in affected extremities after stroke. Immobilization from hemiplegia causes hypercalcemia. Insufficiency or deficiency of 25-hydroxyvitamin D (25-OHD) is very common in stroke patients and may be caused by poor dietary intake, decreased sunlight exposure, or both. Compensatory hyperparathyroidism may not occur because hypercalcemia inhibits the parathyroid glands even when 25-OHD is in the insufficient range. However, hyperparathyroidism does occur when 25-OHD is in the deficient range, in which case the parathyroid response to hypovitaminosis D overrides effects of hypercalcemia. Increased bone resorption was observed during the first year after stroke, declining to normal during the second year. During the first year, determinants of bone mineral density (BMD) in hands affected by hemiplegia were age, severity of hemiplegia, duration of paralysis, serum calcium concentration, and 25-OHD concentration. In the second year, BMD determinants on the hemiplegic side were severity of hemiplegia and 25-OHD concentration, whereas 25-OHD concentration was the only BMD determinant on the intact side. Administering 1alpha-hydroxyvitamin D3, vitamin K2, or ipriflavone ameliorated osteopenia on both sides and decreased the frequency of hip fracture on the hemiplegic side.

CONCLUSIONS

Bone remodeling and determinants of bone mass for the affected and unaffected sides after stroke differ between the first and subsequent years.