Endocrine Abstracts (2012) 29 P239

Correlations between vitamin D supply and PTH-intact and PTH-bio-intact levels in dialysis patients

G. Kovacs1, L. Kovacs2, D. Horvath2, I. Kulcsar2, Z. Locsei2 & E. Toldy1,2

1University of Pecs, Pecs, Hungary; 2Markusovszky Teaching Hospital, Szombathely, Hungary.

Parathormone (PTH) is the marker for bone remodelling in chronic renal failure. The biologically active PTH 1–84 intact molecule (PTHibio) is supposed to better correlate with the degree of remodelling than PTH-intact (PTHi) which also binds to the 1–34 fragment. Our aim was to examine the PTH levels in dialysed patients with these two methods, considering also the total 25-hydroxi-vitamin-D (t-25OHD) levels.

Methods: patients (age 63±15 years) on hemo- (HD) and 37 on peritoneal dialysis (PD, age 62±20 years) were enrolled. PTH was measured by an electro-chemiluminescent immuno-metric assay, while t-25OHD by a protein binding assay (Cobas e411, Roche). Total protein (TP), albumin (ALB), protein electrophoresis and ionized calcium were also determined. The time period spent in dialysis was significantly (P<0.001) lower in PD than in HD (2.1±1.7 vs 4.7±3.8 years).

Results: The t-25OHD level was significantly (P<0.001) lower, while PTH levels (with either method) were significantly higher in PD (PTHi: 302±176 pg/l, PTHibio: 186.3±82.2 pg/ml) than in the HD patients (PTHi: 149.8±89.6 pg/ml and PTHibio: 88.5±50.0 pg/ml). We recorded significantly (P<0.001) lower PTHibio levels compared to PTHi concentrations. Ionized calcium, as well as Alb, TP, and alfa-2-globulin levels were significantly (P<0.01) lower in the PD group. In HD, a significant (P<0.01) negative correlation (−0.52) was confirmed between PTHibio and t-25OHD levels, while no such correlation was present between PTHi and t-25OHD. Conclusions: PD patients suffer from severe vitamin D deficiency. PTHi and PTHibio levels in the PD patients are higher, which could be the consequence of lower ionized calcium and more frequent adynamia, common in PD, despite the relatively shorter time period spent in PD treatment. The lower serum protein levels in PD may explain the particularly low t-25OHD levels. In conclusion, PTHibio seems to be more suitable for monitoring bone metabolism, than any other parameter measured.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.

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