In Native American women, there is a reduction in bone density and a sustained increase in bone turnover postmenopausally. BMI and serum 25OHD are significant determinants of BMD. Peak BMD may be higher, and the postmenopausal rate of bone loss greater, than that in white women.

There is limited information concerning bone mineral density (BMD) and its determinants across a wide spectrum of ages in African American females (AAF). Therefore, we have performed a cross-sectional study of 54 AAF and 39 Caucasian females (CF), aged 20-90 yr, to quantify femoral and lumbar bone mineral density, total body calcium, as well as the potential determinants of bone density. BMD decreased with age in all sites after age 40 yr in both racial groups. Bone density was greater in AAF than in CF, although there was considerable overlap between the two groups. There was no significant difference in the rate of age-related bone loss between the two groups. At the femoral neck, BMD was below the fracture threshold in 28% of the postmenopausal AAF compared to 47% of postmenopausal CF. L1-L4 BMD was below the fracture threshold in 8% of postmenopausal AAF and 11% of postmenopausal CF. Serum-25 hydroxyvitamin D (25OHD) was inversely related to age in both othnic groups and lower (P < 0.05) in premenopausal AAF than CF. Twenty-four percent of the AAF and 22% of the CF had serum 25OHD levels of 8 ng/L or less. Serum PTH was directly related to age (r = 0.43; P = 0.003 in AAF and r = 0.55; P = 0.002 in CF), and 25OHD was inversely related to age (r = -0.43; P = 0.003 in AAF and r = -0.65; P < 0.001 in CF). PTH was higher (P < 0.05) in postmenopausal AAF than in CF. Serum testosterone was greater in AAF than in CF (P < 0.05). Serum estradiol was greater in premenopausal AAF than in CF. Serum dehydroepiandrosterone sulfate was inversely related to age (r = 0.42; P = 0.004 in AAF and r = 0.51; P = 0.005 in CF). Serum osteocalcin was related to age in AAF (r = 0.47; P = 0.001), but not in CF. There was also a trend for an increase in urinary dipyridinoline (expressed per 100 mg urinary creatinine) with age (r = 0.31; P = 0.055 in AAF and r = 0.37; P = 0.066 in CF). Both lean and fat mass were major determinants of femoral neck BMD in AAF. Femoral BMD was directly related to body weight and body mass index in both races. Serum 25OHD and dehydroepiandrosterone sulfate approached statistical significance as independent predictors of femoral BMD in AAF. We conclude that in AAF, 1) bone density is higher than in CF, but there is a significant risk of fracture in a substantial number of subjects on the basis of BMD; 2) there is no difference in rates of age-related bone loss compared to those in CF; 3) both lean and fat mass are significant determinants of bone density; 4) serum estradiol and testosterone were higher than those in CF; and 5) aging is associated with increased bone turnover, 25OHD deficiency, and secondary hyperparathyroidism in both races. The absence of a difference in rates of bone loss between AAF and CF despite higher serum levels of PTH is compatible with the concept of a relative skeletal resistance to PTH in AAF.

We have examined the relationship between self-reported alcohol intake (SRAI), season and mineral metabolism in a series of 96 men aged 32 to 78 years of age. Alcohol intake was reported as between 0 and 50 oz/week. SRAI correlated positively with liver function tests, including serum bilirubin, alkaline phosphatase, and AST initially and at 6 months. In addition, SRAI correlated with serum calcium, testosterone, estradiol, and immunoreactive parathyroid hormone (iPTH) as well as urinary calcium [per 100 mg of creatinine (Cr)], and pyridinoline crosslinks (DPC) (per 100 mg of Cr). We have divided the participants into two groups on the basis of their reported alcohol intake. Individuals with none-to-moderate intake had <8.4 oz/week of ethanol. Those with moderate or heavier intake had 8.4 oz or more of ethanol/week. Individuals with none-to-moderate SRAI had a significant seasonal increase in iPTH, osteocalcin, urine DPC/100 mg of Cr and a decrease in distal forearm bone mineral density, 25 hydroxyvitamin D (250HD), and urinary calcium/100 mg of Cr. Individuals with moderate or heavier SRAI only had significant seasonal decrease in 250HD. We have concluded that alcohol intake decreases seasonal change in serum iPTH. The biological effects of such alterations in parathyroid hormone levels include decreased seasonal loss of bone mineral density.

The mechanisms by which alcohol intake, particularly moderate alcohol intake, effects bone metabolism are poorly defined. We have examined the relationship between mineral metabolism and recent self-reported alcohol intake (SRAI) across a wide range of such intakes in a series of 104 men aged 32 to 78 years of age in an outpatient setting. A morning nonfasting urine, serum specimen and recent SRAI were obtained from each subject. SRAI was reported as between 0 and 45 oz/week. SRAI correlated positively with liver function tests, including serum bilirubin (r = 0.30, p = 0.002), alkaline phosphatase (r = 0.30, p = 0.004), and aspartate aminotransferase (SGOT) (r = 0.29, p = 0.006). SRAI correlated with serum calcium corrected for albumin (r = -0.39, p < 0.001), estradiol (r = 0.43, p < 0.001), and immunoreactive parathyroid hormone (iPTH) (r = -0.51, p < 0.001), as well as urinary calcium (per 100 mg of creatinine) (r = 0.55, p < 0.001). We have arbitrarily divided the participants into two groups on the basis of their reported alcohol intake. Individuals in the first group had intakes ranging from none to moderate intake (drank 8.4 oz or less of ethanol per week, equivalent to an average of two drinks daily or less). Those in the second group had moderate or heavier intake, with >8.4 oz of ethanol intake/week. Mean serum iPTH was significantly greater in those in the first group (none to moderate), compared with the second group (moderate or heavier) (56.0 +/- 3.4 and 39.9 +/- 2.0 pM/liter, respectively). Calcium corrected for serum albumin was significantly greater in individuals in the first, compared with the second, group (9.23 +/- 0.05 vs. 8.88 +/- 0.07 mg/dl, respectively). In addition, urinary calcium (corrected per 100 mg of creatinine) was significantly lower in the former, compared with the latter (3.1 +/- 0.4 vs. 8.4 +/- 1.1 mg/100 mg of creatinine, respectively). Similarly, urinary excretion of collagen crosslinks (corrected per 100 mg of creatinine) was significantly less in men in the second group, compared with the first group (316 +/- 38 vs. 530 +/- 78 nM/100 mg of creatinine, respectively). Not surprisingly, a series of correlations between iPTH and age, 250-hydroxyvitamin D, and testosterone were significant in individuals with none to moderate SRAI, but not moderate or heavier SRAI. Significant independent predictors of serum iPTH in the entire group of men were age (beta = 0.215, p = 0.025), SRAI (beta = -0.281, p = 0.003), 250-hydroxyvitamin D (beta = -0.309, p = 0.002), and testosterone (beta = -184, p = 0.048). We have concluded that, in free-living men, alcohol intake >8.4 oz/week was associated with decreased serum iPTH concentrations.