Bone metabolism and daily physical activity in women undergoing hemodialysis

We investigated the relationships between bone mineral density (BMD) and bone metabolic markers in 41 Japanese women (age range, 23 to 85 years; mean, 61; SD, 16) undergoing hemodialysis, and the relationship between BMD and daily physical activity with nutritional state in those patients.

The patients were divided into a group with hyperparathyroidism (intact parathyroid hormone [PTH] > or = 300 pg/mL, n = 9) and a group without hyperparathyroidism (intact PTH < 300 pg/mL, n = 32). Total BMD and spinal BMD (regional evaluation) were measured using dual-energy X-ray absorptiometry. We determined serum concentrations of intact PTH, osteocalcin (bone Gla protein) and alkaline phosphatase as markers of bone formation, and serum tartrate-resistant acid phosphatase (TRAP) as a marker of bone resorption. Mean energy expenditure per day was measured by calorie counters worn by the patients, and serum levels of total protein, albumin, cholesterol, ferritin, and blood urea nitrogen were measured as indices of nutritional status.

In the group without hyperparathyroidism, 9 patients had a spinal BMD < 0.85 g/cm2 and were considered to be at risk for bone fracture. In this group, a significant correlation was observed between total BMD and TRAP (r = -0.52, p = 0.004). Age, duration of hemodialysis, dry body weight, energy expenditure per day, and serum total protein levels were correlated with total BMD and spinal BMD, using multiple regression analysis (p < 0.0001).

In patients with low BMD, the bone turnover tended toward bone resorption rather than formation, without strong influence by parathyroid function. Energy expenditure showed a strong relationship to the total BMD (r = 0.32, F = 18.5), which appeared to improve bone turnover.