Lipid profile and bone paradox: higher serum lipids are associated with higher bone mineral density in postmenopausal women.

BACKGROUND: Previous studies suggest a relationship between cardiovascular disease (CVD) and osteoporosis; however, the mechanism of the relationship and whether serum lipids are positively or negatively associated with bone mineral density (BMD) are unclear. METHODS: We investigated the relationship among serum lipids, dietary saturated fat, BMD of various skeletal sites, and markers of bone turnover. This was a cross-sectional analysis in 136 Caucasian, healthy, postmenopausal women, who were not taking lipid-lowering medications or drugs affecting bone metabolism. BMD at multiple skeletal sites was assessed by DXA. Concentration of serum triglycerides, cholesterol, osteocalcin (OC), and undercarboxylated osteocalcin (UOC) and urinary cross-linked N-telopeptides were analyzed by routine methods. Saturated fat, total calcium (food and supplements), total vitamin K, alcohol, and energy intake were estimated using 3-day dietary records. Physical activity was assessed and used as a confounder with other anthropometric measurements. RESULTS: Serum triglycerides were positively related to femoral shaft BMD and serum cholesterol to total body BMD (p < 0.05). Also, subjects with serum triglycerides above the median had significantly higher BMD in femoral Ward's triangle than those below the median (p = 0.037, by ANCOVA). Subjects with a serum cholesterol level of > or =240 mg/dL (cutoff for increased risk for CVD) had significantly higher BMD at the total body and at all sites of the femur (except neck). There was no relationship between serum lipids and markers of bone turnover. Saturated fat intake was not associated with BMD of any skeletal site. CONCLUSIONS: These findings indicate that higher levels of serum triglycerides and cholesterol are positively associated with BMD of various skeletal sites. The mechanism of this association is not clear, and studies are needed to clarify this relationship.

Dual hip bone mineral density in postmenopausal women: geometry and effect of physical activity.

The objectives of this study were to (1) obtain both femoral neck strength (FNS) and hip axis length (HAL) values from left and right femurs (regardless of hip dominance) measured by DXA and evaluate their relationship with BMD of all hip regions including total hip, (2) determine if there is a difference between dominant and nondominant hip BMD in any of the hip regions, and (3) determine how physical activity influences hip BMD. Participants were 136, generally healthy Caucasian women (57.4-88.6 years). BMD was measured by DPX-MD. Past and present activity was assessed by the Allied Dunbar National Fitness Survey for older adults and normal/brisk walking pace was measured in a straight hallway. FNS analysis uses femoral geometry to calculate stresses at the femoral neck for two loading conditions: Safety Factor Index (SF) indicates risk of fracture for forces generated during a one-legged stance, and Fall Index (FI) indicates risk of fracture for forces generated during a fall on the greater trochanter. Simple and multiple regression analyses were used to determine predictive ability of HAL, SF, and FI for respective hip BMD values. There was no statistical difference in BMD between two hips in any of the measured regions, however, the nondominant hip correlated better with other skeletal sites. Subjects with a faster normal walking speed had higher neck BMD in the nondominant hip, 0.832 +/- 0.12 vs. 0.791 +/- 0.10 g/cm2 (P < 0.05). Longer HAL of the left hip was negatively related to neck, trochanter, shaft, and total hip BMD. FI was significantly associated with all sites of the hip BMD, while SF was associated only with neck and wards BMC (P < 0.05). In summary: (1) a longer HAL is associated with lower BMD and a higher FI with higher BMD, (2) it might be sufficient to measure BMD in only the nondominant hip, and (3) walking at a faster pace may positively benefit femoral neck BMD. Therefore, it appears that HAL, SF, and FI all play important roles in estimating fracture risk and should be assessed along with BMD when using DXA.

Bone and nutrition in elderly women: protein, energy, and calcium as main determinants of bone mineral density.

OBJECTIVE: Nutrition is an important factor in the prevention and treatment of osteoporosis. Our goal was to examine the relationship between various nutrients and bone mass of several skeletal sites in elderly women, taking into account possible confounding variables. DESIGN/METHODS: A cross-sectional study in 136 healthy Caucasian, postmenopausal women, free of medications known to affect bone was carried out. Bone mineral density (BMD) and body composition (lean and fat tissue) were measured by dual X-ray absorptiometry using specialized software for different skeletal sites. Parathyroid hormone (PTH) and vitamin D, 25(OH)D, as possible confounders, were determined in serum samples. Dietary intake, including all supplements, was assessed by 3-day dietary record and analyzed using Food Processor. Past physical activity and present walking were examined as well and accounted for as potential confounders. Simple and multiple regression models were created to assess the relationships between nutrients and BMD. To examine the co-linear variables and their possible independent association with bone, subgroup analyses were performed. RESULTS: : Showed independent influence of calcium, energy, and protein, examined separately and in multiple regression models on BMD of several skeletal sites. Magnesium, zinc and vitamin C were significantly related to BMD of several skeletal sites in multiple regression models (controlled for age, fat and lean tissue, physical activity and energy intake), each contributing more than 1% of variance. Serum PTH and 25(OH)D did not show significant association with bone mass. CONCLUSIONS: Despite the cross-sectional nature of our study we were able to show a significant relationship between BMD and several critical nutrients: energy, protein, calcium, magnesium, zinc and vitamin C. The exact involvement of these nutrients and their clinical significance in bone health need to be further elucidated in humans and conclusions about the effects of a single nutrient on bone mass must be given cautiously, taking into account its interaction and co-linearity with others. Understanding relationships among nutrients, not just limited to calcium and vitamin D, but others that have not been investigated to such extent, is an important step toward identifying preventive measures for bone loss and prevention of osteoporosis.

Change in bone mass after Colles' fracture: a case report on unique data collection and long-term implications.

The cast immobilization of a fractured limb results in a loss of bone mass; however, the long-term implications of that effect with regard to bone mineral status, particularly in other skeletal sites, are less known. The purpose of this study was to describe changes in bone mass in different skeletal sites triggered by Colles' fracture. The case is unique regarding the existence of baseline measurements taken just a few days before the fracture on all measurable skeletal sites, including the fractured radius. Therefore, it was also possible to determine whether the injury caused long-term bone loss in the affected and unaffected skeletal sites. The patient was a healthy, premenopausal Caucasian woman, in her late forties, who fractured her nondominant wrist as a result of low-impact fall on ice. The arm and the metacarpals were immobilized to the elbow for 5 wk. Bone mass measurements were performed with DPX-MD densitometer (Lunar Corp. Madison, WI) at baseline and 5, 10, 13, 21, and 52 wk postinjury. At the 5-wk measurement (on plaster removal) there was a notable increase in bone mineral density (BMD) and bone mineral content (BMC) in all sites of ulna and radius of the injured forearm (from 10 to 73%), followed by the apparent decline to or below the baseline at 10, 13, 21 and 52 wk of follow-up. Other skeletal sites were measured at 10 wk when a substantial decrease in BMD and BMC in some of the hip regions and lumbar spine was noticed; most notably in L3-L4, Ward's triangle, and femoral neck (from 2 to 8%) and remained such after 1 yr. Although this patient had a normal bone mineral status and no osteopenia detected before fracture, the trauma of radial fracture caused long-standing bone loss in fracture-prone areas-hip and spine. Because about 70% of bone strength is explained by its mineral density, the patient might be at increased risk for fracture later in life. The changes in bone mass after injury should be monitored and interpreted carefully, and more elaborate treatment of patients presenting with wrist fractures are needed to prevent any potential risk for later osteoporotic fractures in spine and hip and possible refracture of the injured extremity.