Endocrine Abstracts

The usefulness of bone mineral density (BMD) and bone turnover markers measurements to assess the renal osteodystrophy in patients with chronic kidney disease, stage 5 (CKD5) are not well determined.

The aim was to analyze BMD, serum levels of parathyroid hormone (PTH) and bone turnover markers in dialysis patients. We examined 45 patients (20 f,25 m; age 45.1±10.8 yrs; age at dialysis onset 40.3±12.3 yrs; dialysis duration 5.0±4.0 yrs). BMD of the lumbar spine (LS), femoral neck (FN) were estimated by DEXA (Lunar). Serum PTH, osteocalcin (OC), C-terminal telopeptide of type I collagen (beta-CTx), alkaline phosphotase (ALP), calcium and phosphates were measured.

Median levels of PTH, OC, beta-CTx were significantly higher, than normal values (688.2 pg/ml; 321.7 pg/ml; 1.66 pg/ml, respectively). We found significant correlation of PTH level and age (r=−0.51), age at dialysis onset (r=−0.57), serum OC (r=0.54), beta-CTx (r=0.72) and ALP (r=0.65). Median BMD, T- and Z-scores in LS (1.15 g/sm²;−0.40;0.07) and FN (0.94 g/sm²;−0.62;−0.27) were normal. Osteopenia and osteoporosis were diagnosed in 20(44.4%) and 5 pts (11.1%), respectively. Comparison of subgroups with low and normal BMD didn’t revealed significant differences in age, age at dialysis onset, dialysis duration, BMI, levels of PTH and bone turnover markers. CaxPO4-product was higher in patients with normal BMD 7.24±1.98 vs 5.32±1.73 in ones with low BMD (P=0.025). In LS Z-score correlated with PTH (r=−0.48; P=0.011), BMD – with CaxPO4-product (r=0.51; P=0.038). In FN we found significant correlation of BMD, Z-score and PTH (r=−0.54;−0.56); Z-score and age, age at dialysis onset (r=0.34;0.31) and serum Ca (r=0.40).

We can assume that low BMD is highly prevalent in CKD5 and associated with high PTH, younger age, and younger age at dialysis onset. Serum OC, beta-CTx, ALP positively correlates with PTH, but similar in patients with different BMD. High CaxPO4-product is well known as an important predictor of cardiovascular morbidity and mortality, but seems to preserve bone loss.