Plasma adiponectin levels are almost twice as high in patients with chronic renal failure in comparison with healthy controls, but not different between renal patients on and those not on hemodialysis. In addition, low plasma adiponectin levels are strongly associated with ischemic heart disease, but not with aortic distensibility in chronic renal failure.

Numerous humoral factors are involved in the development of renal osteodystrophy, causing perturbations in bone mineral density (BMD) in patients with end-stage renal disease (ESRD). The RANKL/OPG cytokine system appears to mediate the effects of many of these factors on bone turnover, contributing to the pathogenesis of renal bone disease. The aim of this study was to evaluate the clinical and biochemical correlations of BMD measurements in patients on chronic hemodialysis. Fifty-four hemodialysis patients underwent measurement of BMD at the proximal femur and the lumbar spine (L2-L4). Intact parathyroid hormone (PTH), osteoprotegerin (OPG), sRANKL, and main bone biochemical markers were also measured in serum samples of all patients. BMD of the femoral neck was negatively correlated with OPG levels (r = 0.333, P = 0.014). OPG levels were significantly different among normal, osteopenic, and osteoporotic tertiles defined according to BMD of the femoral neck. The highest OPG levels were measured in the lowest T-score (osteoporotic) tertile and were higher than in the osteopenic and normal tertiles (P < 0.05). A threshold level for OPG at 21.5 pmol/l enabled the detection of osteoporotic patients with 76.5% sensitivity and 62.2% specificity. BMD values of trabecular bone-rich sites of the skeleton such as lumbar spine (L2-L4), trochanter, and Ward' s triangle were inversely correlated with total ALP levels (P < 0.05). Hemodialysis patients with low BMD of the femoral neck demonstrated higher OPG levels than patients with normal BMD. Those with lumbar spine (L2-L4), trochanteric, and Ward's triangle BMDs below the normal range presented higher total ALP levels. These results suggest that OPG and total ALP may be clinically useful markers in the detection of significant femoral neck and trabecular bone mineral deficit in hemodialysis patients, warranting further investigations.

Hyperphosphatemia is independently associated with an increased risk of death among dialysis patients. In this study, we have assessed the status of phosphate control and its clinical and laboratory associations in a large international group of patients on chronic peritoneal dialysis (PD) treatment. This cross-sectional multicenter study was carried out in 24 centers in three different countries (Canada, Greece, and Turkey) among 530 PD patients (235 women, 295 men) with a mean+/-s.d. age of 55+/-16 years and mean duration of PD of 33+/-25 months. Serum calcium (Ca(2+)), ionized Ca(2+), phosphate, intact parathyroid hormone (iPTH), 25-hydroxy vitamin D(3), 1,25-dihydroxy vitamin D(3), total alkaline phosphatase, and bone alkaline phosphatase concentrations were investigated, along with adequacy parameters such as Kt/V, weekly creatinine clearance, and daily urine output. Mean Kt/V was 2.3+/-0.65, weekly creatinine clearance 78.5+/-76.6 l, and daily urine output 550+/-603 ml day(-1). Fifty-five percent of patients had a urine volume of <400 ml day(-1). Mean serum phosphorus level was 4.9+/-1.3 mg per 100 ml, serum Ca(2+) 9.4+/-1.07 mg per 100 ml, iPTH 267+/-356 pg ml(-1), ionized Ca(2+) 1.08+/-0.32 mg per 100 ml, calcium phosphorus (Ca x P) product 39+/-19 mg(2)dl(-2), 25(OH)D(3) 8.3+/-9.3 ng ml(-1), 1,25(OH)(2)D(3) 9.7+/-6.7 pg ml(-1), total alkaline phosphatase 170+/-178 U l(-1), and bone alkaline phosphatase 71+/-108 U l(-1). While 14% of patients were hypophosphatemic, with a serum phosphorus level lower than 3.5 mg per 100 ml, most patients (307 patients, 58%) had a serum phosphate level between 3.5 and 5.5 mg per 100 ml. Serum phosphorus level was 5.5 mg per 100 ml or greater in 28% (149) of patients. Serum Ca(2+) level was > or =9.5 mg per 100 ml in 250 patients (49%), between 8.5 and 9.5 mg per 100 ml in 214 patients (40%), and lower than 8.5 mg per 100 ml in 66 patients (12%). Ca x P product was >55 mg(2)dl(-2) in 136 patients (26%) and lower than 55 mg(2)dl(-2) in 394 patients (74%). Serum phosphorus levels were positively correlated with serum albumin (P<0.027) and iPTH (P=0.001), and negatively correlated with age (P<0.033). Serum phosphorus was also statistically different (P = 0.013) in the older age group (>65 years) compared to younger patients; mean levels were 5.1+/-1.4 and 4.5+/-1.1 mg per 100 ml, respectively, in the two groups. In our study, among 530 PD patients, accepted uremic-normal limits of serum phosphorus control was achieved in 58%, Ca x P in 73%, serum Ca(2+) in 53%, and iPTH levels in 24% of subjects. Our results show that chronic PD, when combined with dietary measures and use of phosphate binders, is associated with satisfactory serum phosphorus control in the majority of patients.

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