Morphometric dual-energy X-ray absorptiometry of the spine: report of a large series and correlation with axial bone mineral density.

We studied vertebral morphometry and its relation to bone mineral density (BMD) in normal Brazilian women (n = 605). All women (age 22-97 years) were ambulatory and healthy. A lateral spine scan was done for morphometric X-ray absorptiometry using an imaging densitometer. In 429 of these women, BMD of the spine and proximal femur also were measured using dual-energy X-ray absorptiometry. All women were white with mean (+/- 1 SD) age of 53.7 (+/- 9.5) years. About 21% of the women over 50 years had a T score for spine BMD lower than -2.5 SD, and 7% had a femoral neck BMD below this osteoporosis threshold. Vertebral heights (anterior, HA; middle, HM; and posterior, HP) and ratios (HA/HP and HM/HP) were assessed. There was no systematic difference between younger (20-49 years) and older (50+ years) women in heights or ratios. The vertebral heights were normalized for those observed in each individual case for the L2-L4 sequence. This normalization was adequate for all vertebral heights; the Z score averaged about +0.1. The average Z score for HA/HP was +0.01, but that for the HM/HP was -0.72, indicating that the latter ratio might differ from the reference population used (white American and European women). We observed a small positive correlation between vertebral heights and spine or femur BMD, but this was due entirely to the influence of body size on BMD. On a group basis, the HM/HP showed a significant association with axial BMD; the 1 SD difference between the lowest and highest quartile was associated with a difference of 8-15% (0.5-1.0 SD) in axial BMD.

Densidade mineral óssea vertebral e femoral de 724 mulheres brancas brasileiras: influência da idade e do peso corporal / Vertebral and femoral bone mineral sessity of 724 caucasian Brazilian woman: influence of age and body weight

Objetivo. Estudar a densidade mineral óssea (BMD) vertebral (L2-L4) e femoral (colo do fêmur) de mulheres brancas, normais. Material e Método. Mediu-se o BMD de 724 mulheres (40-79 Kg; 20-69 anos de idade) por dual-energy x-ray absorptiometry e analisaram-se os dados em funçao da idade e peso corporal (PC). Resultados. As mulheres mais leves (40-49 Kg) atingiram o BMD maximo (BMDm) vertebral e femoral aos 30-39 anos de idade, enquanto as mais pesadas (60-79 Kg) apresentaram BMDm aos 20 anos. No fêmur, houve uma correlaçao significativa entre BMDm e PC (r=0,97, p<0,001; slope=0,72 por cento/Kg). Em L2-L4, apenas as mulheres com 40-49Kg apresentaram BMDm menor do que as demais(p<0,001). A diminuiçao do BMD vertebral foi mais intensa (-8,3 vs. -5,7 por cento/década) e iniciou mais cedo (quarta vs. quinta década) nas mulheres pesando 40-59Kg do que nas pesando 60-79Kg. A diminuiçao do BMD femoral iniciou logo após o BMDm ser atingido e, até os 69 anos, as mulheres mais pesadas apresentaram um decréscimo 5,3 por cento menor do que aquelas pesando 40-49Kg. O BMD vertebral das mulheres brasileiras foi praticamente o mesmo de uma populaçao norte-americana previamente descrita. Conclusoes. 1) O BMD vertebral e femoral das brasileiras estudadas comportou-se, em funçao da idade, de forma semelhante a de outras populaçoes brancas; 2) havendo o cuidado de corrigir o PC, o BMD das mulheres brasileiras é comparavel ao de mulheres norte-americanas; e 3) o PC é importante na aquisiçao e diminuiçao da massa óssea, além de influenciar a relaçao BMD-idade.

[Vertebral and femoral bone mineral density of 724 caucasian Brazilian women: influence of age and body weight]. / Densidade mineral óssea vertebral e femoral de 724 mulheres brancas brasileiras: influência da idade e do peso corporal.

OBJECTIVE: To study the vertebral (L2-L4) and femoral (neck) bone mineral density (BMD) of normal white women. MATERIAL AND METHOD: We measured the BMD of 724 women (40-79 kg; 20-69 years-age) by dual-energy X-ray absorptiometry. Data were analysed as a function of age and body weight (BW). RESULTS: Thinner women (40-49 kg) attained maximal vertebral and femoral BMD (mBMD) at ages between 30-39 years, while heavier women (60-79 kg) already had the mBMD by the age of 20. At the femur, there was a significant mBMD-BW correlation (r = 0.97; p < 0.001; slope = 0.72%/kg). At the spine, only the 40-49 Kg women exhibited lower mBMD when compared to the others (p < 0.001). The decrease of the vertebral BMD was more intense (-8.3 vs. -5.7%/decade) and started earlier (fourth vs. fifth decade) in women weighting 40-59 kg, as compared to those weighting 60-79 kg. The decrease of the femoral BMD was initiated just after mBMD was achieved and, at the age of 69, heavier women showed a decrease that was 5.3% lower than those weighting 40-49 kg. The vertebral BMD of the Brazilian women was practically the same as reported for a North-American population. CONCLUSIONS: (i) Vertebral and femoral BMD of this Brazilian population varied with age similarly to other white female populations; (ii) provided that appropriate corrections are made for BW, the BMD of Brazilian women is comparable to the BMD of North-Americans; and (iii) the BW is important both in acquisition and decline of bone mass, as it influences the relation BMD-age.

Influence of body composition on the bone mass of postmenopausal women.

AIMS: To investigate the influence of body weight (BW), fat mass (FM) and lean mass (LM) on the bone mineral density (BMD) of several areas of the skeleton. PARTICIPANTS: Sixty one white postmenopausal women (50.1 +/- 4.8 years). MEASUREMENTS: Measurement of BMD by dual energy x-ray absorptiometry. The results were analyzed by linear regression and the slopes of each curve were compared. RESULTS: The results showed that the correlations between BW, FM and LM to BMD were positive, whilst the correlations between age and years since menopause to BMD were negative. LM was the main factor that influence BMD in almost all areas. CONCLUSIONS: FM and LM present a positive effect on BMD, although LM is the main determinant of bone mass. Moreover, higher values of LM and FM present a protective effect against the reduction of BMD combined with menopause. Therefore postmenopausal women with low BW, especially low LM, present serious risk for developing osteoporosis.