Baseline Bone Mineral Density Measurement Research Articles

Coronary artery calcification is associated with smaller increases in femoral neck bone mineral density with anti-resorptive therapy

Abstract Introduction Patients with osteoporosis are at high cardiovascular risk, partly due to vascular calcification, such as in the coronary vessels. It is uncertain if the presence of coronary artery calcification (CAC) effects bone mineral density (BMD) response to anti-resorptive treatment – first line therapy for osteoporosis. We therefore assessed changes in BMD following initiation of anti-resorptive treatment for osteoporosis in patients with and without evidence of CAC. Methods Individuals dispensed at least one prescription for an anti-resorptive medication (bisphosphonates or denosumab) at Monash Health between 2009-2022 were identified. Unique record numbers for these individuals were then cross-matched against the cardiac CT imaging service at Monash Heart (HREC#73603). CAC was detected using a 320-slice CT coronary angiogram (CTCA). We included only those patients having a baseline BMD measurement within two years of CTCA. The annualised percentage change in femoral neck BMD was calculated and adjusted for age, sex, height, weight, and number of years on anti-resorptive treatment. Results 106 individuals were identified of which 85 (women=70 [85%], median age=73 years [interquartile range 64-79 years]) had a follow-up BMD measurement including 19 with, and 66 without, evidence of CAC. Those with CAC were older (76 years versus 64 years, p<0.001). There were 70 bisphosphonate users and 15 denosumab users. Individuals with evidence of CAC experienced, on average, a 1.2% lower increase [(0.345% (0.343 to 0.348) versus -0.881% (-0.883 to -0.879), mean difference -1.226% (-1.493 to -0.959; p<0.05)] in annualised femoral neck BMD with anti-resorptive therapy after adjusting for important clinical risk factors. Interpretation These preliminary data suggests that CTCA-determined CAC may negatively impact femoral neck BMD increases with anti-resorptive therapy. This is perhaps consistent with existing and evolving hypotheses of dysregulatory processes driving ectopic calcium deposition, which we surmise would partially counter the effects of anti-resorptive therapy and potentially manifest as CAC. Thus, of particular interest will be the comparison of cardiovascular outcomes of patients with known CAC with and without anti-resorptive therapy, with the hypothesis that anti-resorptive therapy may potentially have cardioprotective effects in context of CAC. Analysis of the full cohort is underway.Table 1

Serial Bone Density Measurement and Incident Fracture Risk Discrimination in Postmenopausal Women

Repeated bone mineral density (BMD) testing to screen for osteoporosis requires resources. For patient counseling and optimal resource use, it is important for clinicians to know whether repeated BMD measurement (compared with baseline BMD measurement alone) improves the ability to discriminate between postmenopausal women who will and will not experience a fracture. To assess whether a second BMD measurement approximately 3 years after the initial assessment is associated with improved ability to estimate fracture risk beyond the baseline BMD measurement alone. The Women's Health Initiative is a prospective observational study. Participants in the present cohort study included 7419 women with a mean (SD) follow-up of 12.1 (3.4) years between 1993 and 2010 at 3 US clinical centers. Data analysis was conducted between May 2019 and December 2019. Incident major osteoporotic fracture (ie, hip, clinical spine, forearm, or shoulder fracture), hip fracture, baseline BMD, and absolute change in BMD were assessed. The area under the receiver operating characteristic curve (AU-ROC) for baseline BMD, absolute change in BMD, and the combination of baseline BMD and change in BMD were calculated to assess incident fracture risk discrimination during follow-up. Of 7419 participants, the mean (SD) age at baseline was 66.1 (7.2) years, the mean (SD) body mass index was 28.7 (6.0), and 1720 (23%) were nonwhite individuals. During the study follow-up (mean [SD] 9.0 [3.5] years after the second BMD measurement), 139 women (1.9%) experienced hip fractures, and 732 women (9.9%) experienced major osteoporotic fracture. In discriminating between women who experience hip fractures and those who do not, AU-ROC values were 0.71 (95% CI, 0.67-0.75) for baseline total hip BMD, 0.61 (95% CI, 0.56-0.65) for change in total hip BMD, and 0.73 (95% CI, 0.69-0.77) for the combination of baseline total hip BMD and change in total hip BMD. Femoral neck and lumbar spine BMD values had similar discrimination for hip fracture. For discrimination of major osteoporotic fracture, AU-ROC values were 0.61 (95% CI, 0.59-0.63) for baseline total hip BMD, 0.53 (95% CI, 0.51-0.55) for change in total hip BMD, and 0.61 (95% CI, 0.59-0.63) for the combination of baseline total hip BMD and change in total hip BMD. Femoral neck and lumbar spine BMD values had similar ability to discriminate between women who experienced major osteoporotic fracture and those who did not. Associations between change in bone density and fracture risk did not differ by subgroup, including diabetes, age, race/ethnicity, body mass index, or baseline BMD T score. The findings of this study suggest that a second BMD assessment approximately 3 years after the initial measurement was not associated with improved discrimination between women who did and did not experience subsequent hip fracture or major osteoporotic fracture beyond the baseline BMD value alone and should not routinely be performed.

Changes in Bone Mineral Density After Prophylactic Bilateral Salpingo-Oophorectomy in Carriers of a BRCA Mutation

Preventive surgery is strongly recommended for individuals with a BRCA mutation at a young age to prevent ovarian cancer and improve overall survival. The overall effect of early surgical menopause on various health outcomes, including bone health, has not been clearly elucidated. To evaluate the association of prophylactic bilateral salpingo-oophorectomy with bone mineral density (BMD) loss among individuals with a BRCA mutation. This retrospective cohort study of participants with a BRCA mutation who underwent oophorectomy through the University Health Network, Toronto, Ontario, Canada, recruited participants from January 2000 to May 2013. Eligibility criteria included having a BRCA mutation, at least 1 ovary intact prior to surgery, and no history of any cancer other than breast cancer. Bone mineral density was measured using dual-energy x-ray absorptiometry before and after surgery. Data analysis began in December 2018 and finished in January 2019. The annual change in BMD from baseline to follow-up was calculated for the following 3 anatomical locations: (1) lumbar spine, (2) femoral neck, and (3) total hip. A total of 95 women had both a baseline and postsurgery BMD measurement with a mean (SD) follow-up period of 22.0 (12.7) months. The mean (SD) age at oophorectomy was 48.0 (7.4) years. Among women who were premenopausal at time of surgery (50 [53%]), there was a decrease in BMD from baseline to follow-up across the lumbar spine (annual change, -3.45%; 95% CI, -4.61% to -2.29%), femoral neck (annual change, -2.85%; 95% CI, -3.79% to -1.91%), and total hip (annual change, -2.24%; 95% CI, -3.11% to -1.38%). Self-reported hormone therapy use was associated with significantly less bone loss at the lumbar spine (-2.00% vs -4.69%; P = .02) and total hip (-1.38% vs -3.21; P = .04) compared with no hormone therapy use. Among postmenopausal women at time of surgery (45 [47%]), there was also a significant decrease in BMD across the lumbar spine (annual change, -0.82%; 95% CI, -1.42% to -0.23%) and femoral neck (annual change, -0.68%; 95% CI, -1.33% to -0.04%) but not total hip (annual change, -0.18%; 95% CI, -0.82% to 0.46%). This study found that oophorectomy was associated with postoperative bone loss, especially among women who were premenopausal at the time of surgery. Targeted management strategies should include routine BMD assessment and hormone therapy use to improve management of bone health in this population.

The Relationship Between Bone Mineral Density and Cardiovascular Function in Duchenne Muscular Dystrophy: A Retrospective Cohort Study

INTRODUCTION:Duchenne muscular dystrophy (DMD) is an X-linked genetic disorder that causes progressive skeletal and cardiac muscle weakness in boys. Cardiac dysfunction is a frequent cause of death in DMD. Glucocorticoids are the standard of care in DMD. The long-term use of oral glucocorticoids in DMD is complicated by poor bone health. Epidemiological studies suggest a biological link between the loss of bone mineral density (BMD) and cardiovascular disease, including coronary artery and cerebrovascular diseases. Whether an association between low BMD and cardiac dysfunction occurs in DMD boys has not yet been studied. The objective of this retrospective cohort study was to examine the relationship between BMD and cardiovascular health in DMD.METHODS:Retrospective data analyses was performed from de-identified medical records from a tertiary academic medical center. Whole body BMD was measured using dual-energy xray absorptiometry (DEXA) scan and left ventricular ejection fraction (LVEF) was measured using echocardiogram. Linear regression was used to evaluate the relationship between BMD and LVEF.RESULTS:Data was analyzed from a total of 32 boys with DMD. The mean age at which baseline BMD measurements was obtained of 11±3 (SD) years. The worst LVEF was measured at a mean of 23.7±21.8 (SD) months after the baseline BMD measurement. The final adjusted linear regression of the relationship between baseline BMD z-score and worst LVEF was not statistically significant (ß=0.41, p‑value=0.6455).DISCUSSION:In this cohort of boys with DMD, BMD was not associated with LVEF dysfunction up to 79 months later. Future research with a longer longitudinal follow-up period is warranted to evaluate the relationship between BMD and cardiovascular disease in DMD.

A survey of steroid-related osteoporosis diagnosis, prevention and treatment practices of pediatric rheumatologists in North America.

BackgroundThe purpose of our study is to assess practices of North American pediatric rheumatologists regarding monitoring, prevention, and treatment of low bone mineral density (BMD) in children on long-term glucocorticoid treatment.Long-term glucocorticoid therapy is associated with accelerated bone loss. Children with JIA and lupus have low baseline BMD and incident vertebral fractures commonly occur in these groups of patients even after a relatively short period of time being on systemic glucocorticoids. There are no established guidelines for identification, prevention, and treatment of glucocorticoid-induced bone loss in children.MethodsA cross-sectional online survey was conducted with 199 physicians who were listed in the ACR database as practicing pediatric rheumatology in North America.Results86 physicians (43%) responded; 87% were board-certified in pediatric rheumatology. 95% used dual energy X-ray absorptiometry as their primary modality for assessing BMD. 79% “rarely” or “never” obtained a baseline BMD measurement prior to initiation of glucocorticoid therapy. 42% of respondents followed BMD annually. 93% “frequently” or “always” prescribed calcium for patients on long-term corticosteroid therapy; 81% “frequently” or “always” prescribed vitamin D. In patients diagnosed with osteoporosis, 35%-50 % of the practitioners “sometimes”, “frequently” or “always” prescribed bisphosphonates. Bisphosphonates are prescribed at similar rates for male and female patients, and slightly more frequently for pubertal than for pre-pubertal patients. 96% of respondents “rarely” or “never” prescribed calcitonin for patients on long-term glucocorticoid therapy; 92% “rarely” or “never” prescribe this medication for patients with known osteopenia or osteoporosis.ConclusionsUtilization of DXA in children on long-term corticosteroid therapy varies greatly among North American pediatric rheumatologists. Most respondents do not screen for low BMD on a regular basis despite acknowledging the risks of bone loss in this population. Broad consensus appears to be present among practitioners favoring the prescription of calcium and vitamin D for patients receiving long-term corticosteroid therapy. Relatively few respondents consistently recommend bisphosphonate therapy, even for patients with known low bone density; calcitonin is rarely used. These data underscore the need for studies to acquire specific data on bone loss, and its prevention and treatment in young patients on long-term glucocorticoid therapy.

Bone densitometric assessment and management of fracture risk in Indian men of prostate cancer on androgen deprivation therapy: Does practice pattern match the guidelines?

Objective:Estimation of baseline bone mineral density (BMD) at the time of instituting androgen deprivation therapy (ADT) for metastatic prostate cancer is recommended by several specialty groups and expert panels. The present study was carried out to analyze the practice pattern of Indian urologists with regard to bone densitometric assessment and management of fracture risk in men of prostate cancer on ADT, and their degree of adherence to currently available guidelinesMaterials and Methods:Telephonic interviews of 108 qualified urologists, randomly selected from the member database of Urological Society of India was carried out with a predefined questionnaire. The responses were analyzed and compared with the available evidences and recommendations.Results:Only 19.4% urologists routinely perform a baseline BMD before starting ADT. Although majority of them prescribe calcium and vitamin D supplementation, only few tell regarding fracture risk and life-style modification to their patients. While 59.6% of the respondents use Zoledronic acid (ZA) in their patients on ADT, half of them prescribe it without knowing the BMD status, which may lead to overuse of ZA.Conclusion:Majority of the urologists in India do not follow the guidelines for BMD measurement in prostate cancer. A baseline BMD may help in reducing the unnecessary use of ZA.

Prediction of absolute risk of fragility fracture at 10 years in a Spanish population: validation of the WHO FRAX ™ tool in Spain.

BackgroundAge-related bone loss is asymptomatic, and the morbidity of osteoporosis is secondary to the fractures that occur. Common sites of fracture include the spine, hip, forearm and proximal humerus. Fractures at the hip incur the greatest morbidity and mortality and give rise to the highest direct costs for health services. Their incidence increases exponentially with age.Independently changes in population demography, the age - and sex- specific incidence of osteoporotic fractures appears to be increasing in developing and developed countries. This could mean more than double the expected burden of osteoporotic fractures in the next 50 years.Methods/DesignTo assess the predictive power of the WHO FRAX™ tool to identify the subjects with the highest absolute risk of fragility fracture at 10 years in a Spanish population, a predictive validation study of the tool will be carried out. For this purpose, the participants recruited by 1999 will be assessed. These were referred to scan-DXA Department from primary healthcare centres, non hospital and hospital consultations. Study population: Patients attended in the national health services integrated into a FRIDEX cohort with at least one Dual-energy X-ray absorptiometry (DXA) measurement and one extensive questionnaire related to fracture risk factors. Measurements: At baseline bone mineral density measurement using DXA, clinical fracture risk factors questionnaire, dietary calcium intake assessment, history of previous fractures, and related drugs. Follow up by telephone interview to know fragility fractures in the 10 years with verification in electronic medical records and also to know the number of falls in the last year. The absolute risk of fracture will be estimated using the FRAX™ tool from the official web site.DiscussionSince more than 10 years ago numerous publications have recognised the importance of other risk factors for new osteoporotic fractures in addition to low BMD. The extension of a method for calculating the risk (probability) of fractures using the FRAX™ tool is foreseeable in Spain and this would justify a study such as this to allow the necessary adjustments in calibration of the parameters included in the logarithmic formula constituted by FRAX™.

A Before-and-After Study of Fracture Risk Reporting and Osteoporosis Treatment Initiation

Several national organizations recommend that fracture risk assessment and osteoporotic treatment be based on estimated absolute 10-year fracture risk rather than bone mineral density (BMD) alone. To assess the changes in physician prescribing behavior after introduction of absolute 10-year fracture risk reporting. Before-and-after study. Manitoba, Canada, which has an integrated BMD program in which tests are linkable to a population-based administrative health database repository. Women 50 years or older who were not receiving osteoporosis medication (2042 before and 3889 after intervention). Introduction of a system reporting absolute 10-year fracture risk along with dual-energy x-ray absorptiometry results. The proportion of untreated women who were prescribed osteoporosis medications in the year after baseline BMD measurement. Absolute fracture risk reporting reclassified more women (32.7%) into lower-risk categories than into higher-risk categories (10%). This effect was more prominent in women younger than 65 years. Fewer women per physician were prescribed osteoporosis drugs after introduction of absolute fracture risk reporting. The absolute fracture risk reporting system was associated with an overall reduction in osteoporosis medications dispensed (adjusted absolute reduction, 9.0 percentage points [95% CI, 3.9 to 14.2 percentage points]; relative reduction, 21.3% [CI, 9.2% to 33.5%]; P < 0.001). The reduction was attributed to fewer drugs dispensed to women at low and moderate risk for fracture. No differences in fracture rates were observed. This was a nonrandomized study. The risk assessment system studied differs slightly from other 10-year fracture risk assessment models. Change from a T-score-based fracture risk reporting system to a system based on absolute 10-year fracture risk was associated with appropriate, guideline-based changes in prescription of osteoporosis medications. None.

Ten-Year Follow-Up of 3 Years of Oral Adjuvant Clodronate Therapy Shows Significant Prevention of Osteoporosis in Early-Stage Breast Cancer

We have previously reported that 3-year adjuvant clodronate treatment prevents bone loss in breast cancer patients. Here we report the 10-year follow-up data of clodronate in the prevention of treatment-related osteoporosis in women with early-stage breast cancer. Two hundred sixty-eight pre- and postmenopausal, node-positive breast cancer patients were randomly assigned to clodronate, 1.6 g orally administered daily, or to control groups for 3 years. Premenopausal women were treated with adjuvant CMF chemotherapy; and postmenopausal women were treated with antiestrogens, either 20 mg tamoxifen or 60 mg toremifene, for 3 years. The bone mineral density (BMD) of the lumbar spine and hip was measured before treatment and at 1, 2, 3, 5, and 10 years after therapy. Eighty-nine disease-free patients were included in the analyses of osteoporosis-free survival. During the 10-year period, 24 of 89 patients were diagnosed with osteoporosis. Fourteen patients developed spinal osteoporosis (three of 41 in the clodronate group, and 11 of 48 in the control group), and 14 of 89 patients were diagnosed with hip osteoporosis (seven of 41 in the clodronate group, and seven of 48 in the control group). The 10-year spinal, osteoporosis-free survival rate was 92.7% in the clodronate group, and 77.0% in the control group (P = .035). No difference was seen in the frequency of hip osteoporosis (85.4% v 82.9%; P = .92). Baseline BMD measurement had a predictive value of 18 of 24 patients (75%) who developed osteoporosis had osteopenia of the lumbar spine at baseline. Three years of clodronate therapy significantly reduces the incidence of lumbar spine osteoporosis. Patients at risk of developing osteoporosis are among those who have pretreatment osteopenia, that is, baseline BMD measurement has predictive value.

10-year follow-up of the efficacy of clodronate on bone mineral density (BMD) in early stage breast cancer

676 Background: We have previously reported that clodronate prevents bone loss in breast cancer patients (JCO 1997;15:1341, BJC 1997;75(4):602 and EJC 2001;37:2373). Here we report the 10-year follow-up data. Methods: 268 pre- (PRE) and postmenopausal (POST) node positive breast cancer patients were randomized to clodronate (CL), orally 1.6 g daily, or control groups for 3 years. PRE were treated with adjuvant chemotherapy and POST with antiestrogens (AE), tamoxifen 20 mg or toremifene 60 mg, for 3 years. The BMD of the lumbar vertebrae L1–4 (BMDLS) and femoral neck (BMDFN) was measured before the treatment and at 1, 2, 3, 5 and 10 years. 93 patients were eligible for 10-year analyses: 53 PRE and 40 POST. 132 patients had metastatic disease or died and 39 were either lost to follow-up or had to be excluded because having diseases or medications that influences bone metabolism. Results: PRE: BMDLS decreased -12.4% in the control and −8.7% in the CL group in 10 years: from 0 to 3 years −6.9 % vs. −4.2% and from 3 to 10 years −5.5% and −4.5%, respectively. BMDFN decreased −8.8% and −7.2%: from 0 to 3 years −2.9% vs. −2.6% and from 3 to 10 years −5.9% vs. −4.6%, respectively. POST: BMDLS decreased −3.0% in the AE and −1.7% in the AE+CL group in 10 years: from 0 to 3 years −1.5% vs. + 1.2% and from 3 to 10 years −1.5% vs. −2.9%, respectively. BMDFN decreased −7.7% and −6.0%: from 0 to 3 years −0.1% vs. +1.9% and from 3 to 10 years −7.6% vs. −7.9%, respectively. These differences do not reach statistical significance. At 10-years 18 patients had osteoporosis in LS and 15 in FN. Only 4 patients who had osteoporosis at 10 years had normal BMD before the therapy. Conclusions: As reported previously, clodronate prevents the bone loss during treatment in pre- and postmenopausal women. This beneficial effect seems to be maintained at least for 7 years after treatment termination in premenopausal. In postmenopausal women the effect seems to diminish within time. Due to small numbers of patients these differences are no longer statistically significant. Patients at risk of developing osteoporosis are among those who has pretreatment osteopenia i.e. baseline BMD measurement has predictive value. No significant financial relationships to disclose.

Ten-year prediction of osteoporosis from baseline bone mineral density: development of prognostic thresholds in healthy postmenopausal women. The Danish Osteoporosis Prevention Study

Osteopenia is common in healthy women examined in the first year or two following menopause. Short-term fracture risk is low, but we lack algorithms to assess long-term risk of osteoporosis. Because bone loss proceeds at only a few percent per year, we speculated that baseline bone mineral density (BMD) would predict a large proportion of 10-year BMD and be useful for deriving predictive thresholds. We aimed to identify prognostic thresholds associated with less than 10% risk of osteoporosis by 10 years in the individual participant, in order to allow rational osteodensitometry and intervention. We analyzed dual energy X-ray absorptometry (DXA) of the lumbar spine (LS) and femoral neck (FN) from 872 women, who participated in the non-HRT arms of the Danish Osteoporosis Prevention Study and had remained on no HRT, bisphosphonates or raloxifene since inclusion 10 years ago. We defined development of a T -score below -2.5 at the LS and/or FN or incident fracture as end-point, and we derived prognostic thresholds for baseline BMD, defining 90% NPV (negative predictive value) and 90% sensitivity, respectively. Seventy-six percent of the variation in BMD of the LS at 10 years was predicted by baseline BMD. In an individual participant, a baseline BMD T -score above -1.4 (FN or LS, whichever was lower) was associated with a 10-year risk of less than 10% of developing osteoporotic BMD or fracture. This covered 69% of the population. By contrast, participants with T -scores below -1.4 had a 56% risk of fracture or low BMD within 10 years. At the population level, baseline T -score cutoffs below 0 at the LS (68% of the population), 0 at the FN (72%) or -0.6 (62%) at the lower of the two sites capture 90% of the population that developed osteoporosis during the following 10 years. A BMD measurement, performed in the first two years following menopause, is a strong long-term predictor of BMD in healthy women. The association is strong enough to provide robust prognostic thresholds, which can be used to divide the population into two prognostic classes at menopause.

Treatment of established bone loss after renal transplantation with etidronate.

Osteoporosis is a well-documented complication of organ transplantation. Bisphosphonates have been shown to be effective in preventing corticosteroid-induced osteoporosis in renal transplant recipients, but data are lacking for treatment of established osteoporosis. This study reports our clinical experience of treatment with the bisphosphonate etidronate in a single renal transplant center. To establish the effectiveness of etidronate in treating established low bone mineral density (BMD), all newly transplanted patients treated with etidronate were compared with controls. Twenty-five patients treated with etidronate (14 males, 11 females) and 24 controls (15 males, 9 females) were identified from the cohort of patients who underwent transplantation between January 1, 1994, and December 31, 1996. There was no difference in mean age, weight, or cumulative dose of corticosteroids between the treatment and control groups. The baseline BMD measurement was performed at 10.4 +/- 5.3 months after transplantation for treated patients and at 10.7 +/- 4.5 months for controls (P=0.78). Over the subsequent 1-year study period, patients treated with etidronate demonstrated a greater increase in BMD at sites with a preponderance of trabecular bone. Lumbar spine BMD increased 4.3 +/- 6.1% in the treatment group versus 0.55 +/ -5.3% in controls (P<0.03) and trochanter BMD increased 10.3 +/- 11.9% and 2.2 +/- 5.7%, respectively, in the treatment and control groups (P<0.02). This study establishes the effectiveness of etidronate for treatment of low BMD in renal transplant recipients. Patients selected for treatment had lower baseline BMD than control subjects, yet still showed a clinically important increase in BMD.

Changes in bone density with lactation

Objective. —To test the a priori hypotheses that significant bone loss occurs in lactation of greater than 5 months' duration and that bone mass returns to baseline levels when breast-feeding ceases. Design. —Prospective cohort study design of 12 months' duration. Setting. —General community setting with recruitment occurring at birthing education classes. Participants. —Volunteer sample of 98 healthy women of white (n=95) and Asian (n=3) origin, aged 20 to 40 years, and 0 to 1 parity prior to parturition, grouped according to lactation duration: 0 through 1, 2 through 5, and 6 or more months. Main Outcome Measures. —Bone mineral density (BMD) of the proximal femur was measured by dual-energy x-ray densitometry at 2 weeks (baseline), 2 months, 4 months, 6 months, and 12 months following parturition, and BMD of the lumbar spine was measured at baseline, 6 months, and 12 months after parturition. Results. —Women with lactation duration of 6 months or longer had mean BMD losses of 5.1% and 4.8% at the lumbar spine and femoral neck, respectively, comparing baseline values with those at 6 months post partum. Women who breast-fed 0 through 1 month lost no BMD at either bone site. Bone loss in women who breast-fed 6 months or longer was not explained by differences in age, diet, body size, or physical activity. Among women who breast-fed 6 months or longer, there was evidence of return to baseline levels of the lumbar spine at 12 months after parturition. The BMD of the lumbar spine of those women who continued to breast-feed more than 9 months had increased but was still significantly lower than baseline. Conclusion. —Extended lactation (≥70% of energy intake is provided for ≥6 months) is associated with bone loss; however, there is evidence of return to baseline BMD measurement at 12 months after parturition. (JAMA. 1993;269:3130-3135)