Prediction of Fracture Risk II: Other Risk Factors

Bone loss after oophorectomy among high-risk women: an NRG oncology/gynecologic oncology group study

OBJECTIVE

Women undergoing premenopausal oophorectomy for a variety of reasons, including to reduce ovarian or breast cancer risk were evaluated for accelerated bone loss.

METHODS

The Gynecologic Oncology Group (GOG)-0215 randomized phase-II trial of zoledronic acid was initiated to determine if postoophorectomy bisphosphonate therapy could prevent this bone loss. The study was closed after slow accrual prevented evaluation of the primary study endpoint. We analyzed changes in bone mineral density (BMD) among the 80 women randomized to the observation arm of this study, as measured 3, 9, and 18 months postenrollment.

RESULTS

The mean change in BMD from baseline to 18 months was -0.09 (95% CI, -0.12 to -0.07), -0.05 (95% CI, -0.07 to -0.03), and -0.06 (95% CI, -0.07 to -0.05) g/cm across the lumbar spine, right hip, and left hip, respectively. This represents a BMD decrease of -8.5% for the lumbar spine and -5.7% for both the right and left hips from baseline to 18 months' observation.

CONCLUSIONS

These results demonstrate that premenopausal women undergoing oophorectomy clearly experience bone loss, an adverse effect of oophorectomy, which requires attention and active management. BMD should be monitored postoophorectomy, and treated per standard practice guidelines. Future studies will be required to determine if early treatment can mitigate fracture risk, and to test promising therapeutic interventions and novel prevention strategies, such as increased physical activity or alternative medications, in randomized trials.

Hipervitaminose D em animais

Por meio de revisão da literatura, são apresentados dados referentes ao metabolismo da vitamina D, bem como aos principais aspectos toxicológicos, clínicos, bioquímicos, macroscópicos, microscópicos, ultraestruturais, imuno-histoquímicos e radiográficos de animais intoxicados natural e experimentalmente por essa vitamina, em diferentes espécies. Este estudo objetiva demonstrar a existência de muitas lacunas no conhecimento sobre mineralização fisiológica e patológica, em especial na mediação hormonal do fenômeno, bem como alertar para os riscos de ocorrência dessa intoxicação.

Does inadequate diet during childhood explain the higher high fracture rates in the Southern United States?

SUMMARY

Southern states have the highest age-adjusted hip fracture rates among older adults in the United States. Regional hip fracture rates in the United States in 1986-1993 correlate with death rates from rickets in the 1940s. Historical patterns of bone nutrition early in life might explain contemporary geographic patterns in bone fragility.

INTRODUCTION

State of residence early in life is a better predictor of the risk of hip fracture after age 65 than state of current residence. Therefore, the geography of rickets mortality in the United States before 1950 was compared with the geography of hip fracture rates among older adults in the United States during 1986-1993.

METHODS

Vital statistics data for the US white population for 1942-1948 allowed calculation of the ratio of deaths from rickets to live births for each geographic division of the USA. These ratios were correlated with previously published, standardized hip fracture rates among whites 65-89 years old during 1986-1993 by census division.

RESULTS

During 1942-1948, the rickets mortality ratio among whites was 3.11 in the South, 1.91 in the Northeast, 1.75 in the Midwest, and 1.04 in the West. The correlation of mortality with risk of hip fracture was 0.71 (p = 0.03) for both sexes combined and 0.86 (p = 0.01) for women.

CONCLUSIONS

Inadequate nutrition during skeletal formation early in life might explain the higher incidence of hip fracture among older adults in the South.

Osteoporosis Preventive Behavior in Thai Older Adults: Feasibility and Acceptability

The authors used a one-group pre-test-post-test design to examine the feasibility and acceptability of an osteoporosis prevention program and the effects of the program on knowledge, health beliefs, self-efficacy; and osteoporosis preventive behaviors in older adults. Participants included 48 older adults who attended a health center in Thailand. Results revealed that the program was feasible and acceptable. A significant improvement in osteoporosis knowledge, health beliefs, self-efficacy, and osteoporosis preventive behaviors occurred. Findings suggest that the program helps older adults incorporate new knowledge and skills into their daily lives and helps them maintain bone health.

Age-related cortical bone loss in women from a 3rd–4th century AD population from England

Age-dependent cortical bone loss in adult females from a skeletal assemblage from 3rd-4th century AD England was studied using metacarpal radiogrammetry. Results showed reduced peak cortical bone thickness compared with modern subjects, and the magnitude of cortical bone loss in older females compared with their younger counterparts was greater than that documented for a modern reference population. An elevated prevalence of fractures classically associated with osteoporosis was also observed in the over-50-year cohort. The severity of osteoporosis in this group is difficult to explain in terms of extraneous factors relating to 3rd-4th century lifestyles. Given the important genetic component in osteoporosis, the results may indicate some inherent susceptibility in this particular population to the disease, and ways in which this possibility might be further explored are suggested.

Osteoporosis in a population from medieval Norway

Modern populations from Norway and England differ in their experience of osteoporosis, the former showing lower bone mineral density (BMD) and a higher fragility fracture rate. The aim of the present work was to investigate whether this was also the case during the Middle Ages. Age-dependent loss of BMD in the proximal femur was assessed using dual X-ray absorptiometry (DXA) in male and female adult skeletons from a cemetery in the medieval town of Trondheim, Norway. Fracture prevalence was also investigated. Results were compared with those previously reported for a skeletal series from Wharram Percy, a deserted medieval village in England. Results indicate that peak BMD and patterns of age-related loss of BMD in the Norwegian and the English group were similar. Among females, the prevalence of osteoporotic fractures was greater in the Norwegian than in the English population. The BMD results suggest that differences in BMD between English and Norwegians are of recent origin, although given the fairly modest sample sizes, further work is needed to confirm this. Reasons for the greater prevalence of osteoporotic fractures in women in the Norwegian skeletal series are unclear, but the colder climate and greater frequency of hard surfaces may have meant that falls were more frequent, and when they occurred, were more likely to result in fractures than in the rural English group.

Efeito da associação hipotireoidismo-castração no osso e nas paratireóides de ratas adultas

O efeito do hipotireoidismo sobre o metabolismo ósseo e as paratireóides na deficiência ou suficiência dos esteróides ovarianos foi estudado em 32 ratas Wistar, com 2 meses de idade, distribuídas em 4 grupos de 8: eutireóideo não castrado (ENC), eutireóideo castrado (EC), hipotireóideo não castrado (HNC) e hipotireóideo castrado (HC). Após 120 dias de tratamento, as ratas foram sacrificadas e o plasma colhido para dosagem de T4 livre. Foi evidenciada hipertrofia das paratireóides somente no grupo HNC. As ratas do grupo HNC apresentaram osteopenia de maior extensão e intensidade, decorrente do menor crescimento, da inibição da aposição e do aumento da reabsorção ósseas. Nas ratas EC, a osteopenia foi causada por menor aposição e aumento da reabsorção ósseas. Embora a osteopenia na associação hipotireoidismo-castração tenha sido quase sempre mais intensa em relação à das ratas EC, sua intensidade, quando comparada à osteopenia dos animais HNC, foi variável e dependente do sítio ósseo estudado. Apesar de causar necrose dos ossos de maior metabolismo, a associação hipotireoidismo-castração não potencializou a osteopenia decorrente da ação isolada do hipotireoidismo até os 120 dias de tratamento.

A osteoporose e os distúrbios endócrinos da tireóide e das gônadas

Apesar da dedicação incessante dos pesquisadores no estudo da osteoporose, muito ainda necessita ser elucidado. A deficiência dos esteróides sexuais, principalmente a de estrógeno, é considerada a principal causa de osteoporose, embora existam inúmeros outros fatores envolvidos. O hipertireoidismo, por exemplo, é considerado um dos fatores de risco para indução ou agravamento da osteoporose e tem despertado o interesse para o estudo dos efeitos de T3 e T4 sobre o metabolismo ósseo. Embora o hipotireoidismo e a afuncionalidade das gônadas seja uma associação freqüente na mulher, a hipofunção da tireóide não é considerada fator de risco para a osteoporose da menopausa. Assim, o estudo da inter-relação entre os distúrbios endócrinos, tão comuns na idade avançada, e a osteoporose é fundamental, pois deste conhecimento poderão advir meios de controle e tratamento adequados, bem como a definição da real natureza do distúrbio ósseo. O objetivo desta revisão é apresentar e discutir alguns aspectos da osteoporose e sua inter-relação com os distúrbios endócrinos da tireóide e das gônadas.

Relação tireóide-gônadas e níveis plasmáticos de fósforo, cálcio e fosfatase alcalina em ratas

A relação tireóide-gônadas-metabolismo ósseo foi estudada em ratas Wistar adultas, castradas ou intactas e mantidas em estado hipertireóideo ou eutireóideo por períodos de 30, 60 e 90 dias. Foram utilizadas como características do metabolismo ósseo o cálcio, o fósforo e a atividade da fosfatase alcalina plasmáticos, correlacionando-os com os valores de estrógeno, de progesterona e de T4 livre. Verificou-se que o hipogonadismo e o hipertireoidismo alteram as características plasmáticas do metabolismo ósseo. O hipertireoidismo induz hiperfosfatemia e hipocalcemia, o hipogonadismo tem pouca influência sobre o fósforo, mas potencializa a hiperfosfatemia e a hipocalcemia desencadeadas pelo hipertireoidismo. Com relação à fosfatase alcalina, conclui-se que o hipertireoidismo reduz o efeito do hipogonadismo sobre a atividade dessa enzima.

Interpretation of calcaneus dual-energy X-ray absorptiometry measurements in the assessment of osteopenia and fracture risk

Dual-energy X-ray absorptiometry (DXA) of the calcaneus is useful in assessing bone mass and fracture risk at other skeletal sites. However, DXA yields an areal bone mineral density (BMD) that depends on both bone apparent density and bone size, potentially complicating interpretation of the DXA results. Information that is more complete may be obtained from DXA exams by using a volumetric density in addition to BMD in clinical applications. In this paper, we develop a simple methodology for determining a volumetric bone mineral apparent density (BMAD) of the calcaneus. For the whole calcaneus, BMAD = (BMC)/ADXA3/2, where BMC and ADXA are, respectively, the bone mineral content and projected area measured by DXA. We found that ADXA3/2 was proportional to the calcaneus volume with a proportionality constant of 1.82 +/- 0.02 (mean +/- SE). Consequently, consistent with theoretical predictions, BMAD was proportional to the true volumetric apparent density (rho) of the bone according to the relationship rho = 1.82 BMAD. Also consistent with theoretical predictions, we found that BMD varied in proportion to rho V1/3, where V is the bone volume. We propose that the volumetric apparent density, estimated at the calcaneus, provides additional information that may aid in the diagnosis of osteopenia. Areal BMD or BMD2 may allow estimation of the load required to fracture a bone. Fracture risk depends on the loading applied to a bone in relation to the bone's failure load. When DXA is used to assess osteopenia and fracture risk in patients, it may be useful to recognize the separate and combined effects of applied loading, bone apparent density, and bone size.

Age-dependent cortical bone loss in women from 18th and early 19th century London

Age-dependent cortical bone loss was investigated in an earlier British population. The study sample comprised female skeletons from the 18th/19th century crypt at Christ Church, Spitalfields, London. Bone loss was monitored using metacarpal radiogrammetry. Age at death was known exactly from coffin plates. Results indicated that peak cortical thickness was less than in modern subjects. Continuing periosteal apposition was evident throughout adulthood, and the rate of increase in metacarpal diameter resembled that in modern subjects. Bone loss from the endosteal surface was evident from the fifth decade onwards, and this outstripped the rate of subperiosteal gain so that there was a net loss of cortical bone with age. Cortical bone loss occurred at a similar rate to that in modern subjects. In contrast to modern populations, there was no evidence that loss of cortical bone was associated with increased propensity to fracture. The present results, together with those previously published for a British medieval skeletal assemblage, suggest that patterns of cortical bone loss in women have remained unchanged over at least the last millennium in Britain. Given the great changes in lifestyle which have occurred during this period, this suggests that lifestyle factors may be rather less important than is sometimes asserted in influencing the severity of osteoporosis, at least as far as loss of cortical bone is concerned.