Correlation between 25-hydroxyvitamin D levels and latitude in Brazilian postmenopausal women: from the Arzoxifene Generations Trial.

SUMMARY: We investigated vitamin D status in Brazilian cities located at different latitudes. Insufficiency (<50 nmol/L) was common (17 %), even in those living in a tropical climate. Vitamin D insufficiency increased as a function of latitude. Mean 25-hydroxyvitamin D (25(OH)D) levels in each site and latitude correlation were very high (r = -0.88; p=0.02). [corrected]. INTRODUCTION: Inadequate vitamin D, determined by low levels of 25(OH)D, has become very common despite the availability of sunlight at some latitudes. National data from a country that spans a wide range of latitudes would help to determine to what extent latitude or other factors are responsible for vitamin D deficiency. We investigated vitamin D status in cities located at different latitudes in Brazil, a large continental country. METHODS: The source is the Brazilian database from the Generations Trial (1,933 osteopenic or osteoporotic postmenopausal women (60 to 85 years old) with 25(OH)D measurements). 25(OH)D below 25 nmol/L (10 ng/mL) was an exclusion criterion. Baseline values were between fall and winter. The sites included Recife, Salvador, Rio de Janeiro, São Paulo, Curitiba, and Porto Alegre. Mean and standard deviation of 25(OH)D, age, spine and femoral neck T-score, calcium, creatinine, and alkaline phosphatase were calculated for each city. Pearson correlation was used for 25(OH)D and latitude. RESULTS: Insufficiency (<50 or <20 ng/mL) was common (329 subjects, 17 %). Vitamin D insufficiency increased as a function of latitude, reaching 24.5 % in the southernmost city, Porto Alegre. The correlation between mean 25(OH)D levels in each site and latitude was very high (r = -0.88, p < 0.0001). CONCLUSION: There is a high percentage of individuals with vitamin D insufficiency in Brazil, even in cities near the equator, and this percentage progressively increases with more southern latitudes.

Osteoporosis after solid organ transplantation.

Osteoporosis and high risk of fractures have emerged as frequent and devastating complications of organ solid transplantation process. Bone loss after organ transplant is related to adverse effects of immunosuppressive drugs on bone remodeling and bone quality. Many factors contribute to the pathogenesis of osteoporosis in transplanted patients. This review address the mechanisms of bone loss that occurs both in the early and late post-transplant periods including the contribution of the immunosuppressive agents as well as the specific features to bone loss after kidney, lung, liver and cardiac transplantation. Therapy for bone loss and prevention of fragility fracture in the transplant recipient will also be discussed.

Androgens and bone.

Testosterone is the major gonadal sex steroid produced by the testes in men. Androgens induce male sexual differentiation before birth and sexual maturation during puberty; in adult men, they maintain the function of the male genital system, including spermatogenesis. Testosterone is also produced in smaller amounts by the ovaries in women. The adrenal glands produce the weaker androgens dehydroepiandrosterone, dehydroepiandrosterone sulfate, and androstenedione. Because testosterone can be metabolized to estradiol by the aromatase enzyme, there has been controversy as to which gonadal sex steroid has the greater skeletal effect. In this respect, there is increasing evidence that at least part of the effects of androgens in men can be explained by their aromatization into estrogens. The current evidence suggests that estradiol plays a greater role in maintenance of skeletal health than testosterone, but that androgens also have direct beneficial effects on bone.

Chronic obstructive pulmonary disease is associated with osteoporosis and low levels of vitamin D.

UNLABELLED: We did a cross-sectional analysis of chronic pulmonary obstructive disease (COPD) patients without chronic use of systemic glucocorticoids (CUG). Osteoporosis was found in 51% and bone mineral density (BMD) was correlated with severity of disease. Low levels of vitamin D were found in 94%. All COPD patients may benefit from vitamin D supplementation and screening for low BMD. INTRODUCTION: Patients with chronic pulmonary obstructive disease have low bone mineral density, caused by chronic use of systemic glucocorticoids and hypovitaminosis D. However, patients without CUG may also have low BMD. METHODS: We performed a cross-sectional analysis in 49 patients (21 men, 28 postmenopausal women), with COPD without CUG, from Brazil (25 degrees 25' S). Several markers of bone metabolism were measured, plus BMD. Osteoporosis risk factors and history of fractures were investigated. Respiratory function was assessed by venous gasometry, spirometry, and oximetry. BMD results were compared to those of 40 healthy non-smokers controls. RESULTS: COPD patients had lower BMD at all sites (p < 0.01). Osteoporosis was observed in 51%. BMD independently correlated with stage of disease (lumbar spine, R = 0.38, p = 0.01; total femur, R = 0.36, p = 0.01; femoral neck, R = 0.40, p < 0.01). Ninety-four percent had low levels of vitamin D (<30 ng/mL) and 67% had secondary hyperparathyroidism. Vitamin D was correlated with oxygen saturation (R = 0.36, p = 0.01), with lower levels in those with saturation <88% (p = 0.01). CONCLUSION: Patients with COPD without CUG have increased risk for osteoporosis. Such patients have hypovitaminosis D, which is correlated with the severity of disease. Screening for low BMD and vitamin D supplementation may be warranted to all COPD patients.

Bone densitometry: the best way to detect osteoporosis and to monitor therapy.

The revolution in the field of osteoporosis has been aided and abetted by the advent of bone mass measurement technologies. As they become more widely applicable and more affordable, it is evident that we have the potential to discover the millions of individuals at risk for or with the disease. With effective therapies at hand, it is now possible to prevent and treat osteoporosis. There is every reason, therefore, to apply bone mass measurements as widely as possible to discover those subjects at risk for osteoporosis in a manner that is effective and affordable.

Osteoporosis and low bone mass in premenopausal and perimenopausal women.

OBJECTIVE: To characterize the historical, clinical, and biochemical features of 111 young women (age, <55 years) referred for evaluation of osteoporosis or low bone mass. METHODS: Women with a bone mineral density T score < or = -2.0 (N = 111) at one or more anatomic sites (by dual-energy x-ray absorptiometry) were assessed relative to anthropomorphic and biochemical characteristics and risk factors for osteoporosis. RESULTS: Of 111 women with low bone mass or osteoporosis, 73 (66%) had identifiable causes of bone loss, of which estrogen deficiency (menopause, premenopausal estrogen deficiency) and conditions associated with estrogen deficiency (anorexia nervosa, cancer chemotherapy) were the most common. Prolonged use of glucocorticoids was the most common secondary cause of osteoporosis. Of 38 women with no identifiable cause of bone loss, 21 were premenopausal (mean age, 38 +/- 10 years [standard deviation]) and 17 were perimenopausal (mean age, 50 +/- 3 years). The mean lumbar spine T score was -2.18 +/- 1.0 in the premenopausal and -2.51 +/- 0.6 in the perimenopausal women. Nontraumatic fractures were reported by 42% of the premenopausal women and 18% of the perimenopausal women. A family history of osteoporosis was reported by 71% of the premenopausal and 47% of the perimenopausal women. CONCLUSION: Most young women with osteoporosis or low bone mass had estrogen deficiency or another secondary cause of premature bone loss (or both). A subset of premenopausal and perimenopausal women, however, had no identifiable cause of bone loss. The strong family history of osteoporosis, especially in the premenopausal women, provides further support for current theories of a genetic predisposition to osteoporosis.

Osteoporosis: preventive strategies.

In the United States alone, osteoporosis affects over 20 million women. The cost of treating the complications of osteoporosis exceeds 10 billion dollars. Half of those who sustain a hip fracture never return to their former life style. In addition, there is a major increase in mortality within the first year of a hip fracture. These facts dictate an urgent need to address issues relevant to the prevention of osteoporosis. Only by preventing bone loss will it be possible to meet the challenge of dealing effectively with this major public health problem. There are three major components of an effective preventive strategy. The first is to ensure that optimal peak bone mass is achieved during childhood, adolescence and early adulthood. Although much of peak bone mass is determined by genetic influence, there are other factors of importance over which one has control. These include adequate dietary calcium intake, good nutrition, exercise and hormone sufficiency. The second aspect to prevention is maintaining bone mass that has been acquired. Bone maintenance requires adequate calcium intake and exercise as well as avoiding tobacco and excessive alcohol. Certain diseases (i.e., hyperthyroidism) and medications (i.e., steroids, anticonvulsants) will tend to erode the repositories of bone at any time in life. The third aspect to prevention is counteracting the process of age-related bone loss that occurs after 40-45 years of age. In women, the menopause markedly accelerates bone loss. Measures to ensure that bone loss is minimized during the middle years and beyond include adequate nutrition (vitamin D and calcium) and hormone sufficiency. For women, hormone replacement therapy is a gold standard of therapy because it arrests bone loss associated with the menopause. For women who cannot or will not take estrogen, newer, effective approaches, such as estrogen analogues and the nonhormonal bisphosphonates, are available. With this three-phased approach, requiring constant attention to bone health over one's entire life, the risk of developing osteoporosis and its complications can be minimized.

Bone mass measurement in identification of women at risk for osteoporosis.

It is now possible to measure bone mass with highly precise, safe and noninvasive technology. Dual energy X-ray absorptiometry (DXA) can detect bone loss well before it becomes evident by conventional X-rays or by fracture. Because measurement of bone density is the single most important predictor of fracture risk, it is a critically important tool to apply to the population at risk, which includes women who have definable risk factors for osteoporosis, such as the menopause, as well as those with a family history of osteoporosis, life-long low calcium intake, smoking, extreme thinness, anorexia, certain diseases and medications. Central DXA machines measure bone mass of the lumbar spine and hip region, the most important potential fracture sites. At the present time, the number of DXA machines in the United States is inadequate to detect the entire population at risk. Even if there were a sufficient number of DXA machines, lack of insurance reimbursement would limit their use. These restraints are beginning to be better defined, if not moderated, by the Bone Mass Measurement Act of 1998. With insufficient numbers of DXA machines and their heavy localization to major urban medical centers, peripheral devices have been developed. Using DXA technology, these peripheral devices can measure densities in the distal forearm, the middle phalangeal bone, and the heel. Ultrasound technology has also been developed to measure bone density of the tibia and the heel. The peripheral densitometers, in general, have the advantage of smaller size, lower cost, and portability. A very controversial issue, however, is whether measurement at a peripheral site provides sufficiently accurate information about bone mass at more important central sites to be generally reliable. Nevertheless, they have great potential in helping to detect the large numbers of women at risk for osteoporosis. Eventually, however, central measurements of bone mass will be needed, especially for monitoring of therapy, so that central measurements of bone mass by DXA are still the "gold standard" in the field at this time.

Bone turnover 18 months after a single intravenous dose of zoledronic acid.

Zoledronic acid inhibits bone resorption for up to 12 months. It is not known whether the duration of this antiresorptive effect extends beyond this period of time. The aim of this study was to evaluate the changes in bone turnover at 12 months (T12) and 18 months (T18) after a single injection of 4 mg of zoledronic acid. It is a prospective, longitudinal study, with a follow-up for 18 months. We studied male and female patients (60.5 +/- 11.0 years old), with low bone mineral density (BMD) coming from the outpatient clinic in a metabolic bone unit of a tertiary care hospital. All patients received a single intravenous dose of 4 mg of zoledronic acid, bone turnover markers [serum carboxyterminal telopeptide of type I collagen (CTX-I), bone-specific alkaline phosphatase (BSAP)] and BMD [lumbar spine (LS) and total hip (TH)] were measured at baseline, and after 12 months (T12) and 18 months (T18). Median serum CTX-I and BSAP levels were suppressed at T12 in comparison with baseline values: 0.183 to 0.039 ng/ml for CTX-I (p = 0.0002) and 16.95 to 13.96 U/l for BSAP (p = 0.005). At T18, both CTX-I and BSAP continued to be suppressed below baseline at 0.108 ng/ml and 12.23 U/l (p = 0.009 and p = 0.02, vs. T0). Significant increases in BMD at T18 as compared with T12 were observed in patients (median increase 6.1% for LS and 2.0% for TH). Zoledronic acid inhibits bone turnover effectively for 12 months, with evidence for continued suppression and gains in BMD even after 18 months.