Different cutoff points to diagnose low muscle mass and prediction of osteoporosis in postmenopausal women

Associations between bone mass, hormone levels, and body composition in postmenopausal women

OBJECTIVES

The aim of this study was to explore body composition parameters and hormone levels as risk factors for low bone mass (osteopenia/osteoporosis) in postmenopausal women.

METHODS

We analyzed biorepository samples from 139 postmenopausal women with no clinical evidence of cardiovascular disease. Inclusion criteria were menopause occurring after 40 years of age and no use of hormone therapy in the past 3 months. Bone mineral density and body composition were assessed by dual-energy x-ray absorptiometry. Sex hormone-binding globulin (SHBG) and follicle-stimulating hormone (FSH) levels were measured in all participants. Serum estradiol was measured by gas chromatography/tandem mass spectrometry in a subset of 57 participants. Free estrogen index was calculated by dividing estradiol by SHBG × 100.

RESULTS

Body mass index (25.0 [22.5-26.5] vs 27.7 [26.6-31.9] kg/m 2 , P < 0.001), estradiol (3.0 [2.7-4.5] vs 6.0 [2.7-15.0] pg/mL, P = 0.006), waist circumference (84 ± 9 vs 93 ± 12 cm, P < 0.001), appendicular lean mass (ALM) (15.739 ± 2.129 vs 17.184 ± 2.104 kg, P = 0.001), and fat mass index (9.36 [7.29-11.43] vs 11.38 [9.95-15.33] kg/m 2 , P < 0.001) were lower in women with low bone mass by dual-energy x-ray absorptiometry. Univariate analysis showed that free estrogen index, time since menopause, SHBG, and fat mass were significant predictors of low bone mass, and ALM was a significant predictor against low bone mass. Appendicular lean mass persisted as an independent predictor against low bone mass in multivariate models with fat mass and SHBG. In turn, fat mass was no longer significant in this multivariate model after inclusion of SHBG. No association of FSH with low bone mass was observed.

CONCLUSIONS

Appendicular lean mass was a significant independent predictor against low bone mass in postmenopausal women. Further prospective studies are needed to investigate whether lean mass, fat mass, and FSH have a direct effect on bone mass in postmenopausal women, adding to the consequences of hypoestrogenism in this group.

Relationship of sarcopenia with bone geometry and mass among postmenopausal women

OBJECTIVE

The aim of this study was to verify whether sarcopenia and its components are associated with hip areal bone mineral density (aBMD) and geometry in postmenopausal women (PW).

METHODS

In this cross-sectional study, appendicular bone-free lean mass (aLM) and hip bone mass and geometry were measured using dual-energy x-ray emission absorptiometry (DXA). Muscle power and strength were measured by five times Sit-to-Stand Test (5-STS) and dynamometry, respectively, in 175 PW. Sarcopenia was identified as low aLM plus low muscle strength or low muscle power. Multiple linear regression (covaried by age, smoking, hormonal therapy, and diseases) was used to determine the relationship between sarcopenia and bone geometry and mass. The results are presented as mean differences between groups.

RESULTS

Dynamometry, five times Sit-to-Stand Test, and aLM indicated positive associations (P < 0.05) with most indicators of bone mass and geometry. Sarcopenia, applying low muscle strength or low muscle power, was negatively associated with femoral neck width (-0.2 mm, P = 0.001), cortical thickness of femoral calcar (-0.6 mm, P = 0.043), subtrochanteric cortical thickness (-1.2 mm, P = 0.002), femoral neck cross-sectional area (-19.5 mm2, P < 0.001), cross-section moment of inertia (-2,244 mm4, P < 0.001), section modulus (-115 mm3, P < 0.001), femoral neck aBMD (-0.1 g/cm2, P = 0.002), upper femoral neck aBMD (-0.1 g/cm2, P = 0.003), lower femoral neck aBMD (-0.1 g/cm2, P = 0.016), and trochanteric aBMD (-0.1 g/cm2, P = 0.035).

CONCLUSIONS

Thus, muscle mass, strength and power, alone or in combination (ie, sarcopenia), are associated with low aBMD, impaired bone geometry, and, therefore, bone strength in PW. These measures may help identify PW at risk of hip fractures.

Is sarcopenia associated with osteoporosis? A cross-sectional study of 262 women with hip fracture

BACKGROUND

Several lines of evidence support the view that sarcopenia and osteoporosis are strictly connected. However, the capability of the updated sarcopenia definition to capture the concomitant presence of osteoporosis has been scarcely investigated.

AIM

The main aim was to assess the association between sarcopenia defined according to the revised criteria from the European Working Group on Sarcopenia in Older People (EWGSOP2) and osteoporosis in women with a hip fracture. A second aim was to investigate the thresholds for low appendicular lean mass (aLM) and handgrip strength to optimize osteoporosis detection.

DESIGN

Cross-sectional study.

SETTING

Rehabilitation hospital.

POPULATION

Women with subacute hip fracture.

METHODS

A scan by dual-energy X-ray absorptiometry (DXA) was performed to assess body composition. A Jamar dynamometer was used to measure handgrip strength. Sarcopenia was diagnosed with both handgrip strength <16 kg and aLM <15 kg. Osteoporosis was identified with femoral bone mineral density lower than 2.5 standard deviations below the mean of the young reference population.

RESULTS

We studied 262 of 290 women. Osteoporosis was found in 189 of the 262 women (72%; 95% CI: 67-78%) whereas sarcopenia in 147 (56%; 95% CI: 50-62%). After adjustment for age, time interval between fracture and DXA scan and body fat percentage the odds ratio to have osteoporosis for a sarcopenic woman was 2.30 (95% CI: 1.27-4.14; P=0.006). Receiver operating characteristic curve analyses showed that the best cut-off points to discriminate osteoporosis were 20 kg for handgrip strength and 12.5 kg for aLM. Adopting the optimized thresholds to define sarcopenia, the adjusted odds ratio to have osteoporosis for a sarcopenic woman was 3.68 (95% CI: 1.93-7.03; P<0.001).

CONCLUSIONS

This preliminary study shows a positive association between sarcopenia defined according to the EWGSOP2 criteria and osteoporosis in 262 women with hip fracture. The association may be bettered by refining the cut-off points for low aLM and handgrip strength.

CLINICAL REHABILITATION IMPACT

Sarcopenia seems to be a risk factor for osteoporosis in hip-fracture women. The issue, and the potential role of optimized thresholds should be addressed by robust longitudinal studies.