Table 3.

Estimation of variance components for intact PTH in hemodialysis patients

Intact PTHNumber of PatientsIntact PTH Concentration (mean (SD)), ng/LCVA(%)CVI(%)RCV (%)Number of Samples
±10%±20%±30%
Tertile 1760.8 (34)3.6931.78839104
Tertile 28206 (111)3.3627.2762973
Tertile 37660 (161)3.874.516111
<300 ng/L13104 (73)3.4631.2873894
≥300 ng/L9592 (110)3.8913.9a40821
AM patients9187 (227)3.4632.18940104
PM patients13383 (276)3.7419.8b561642
  • Variance components were used to calculate the critical difference for changes in serial results (RCV) to be considered as significant (P < 0.05) and the number of samples required to estimate the homeostatic set point of an individual (within ±10%, 20%, and 30% with a confidence of 95%).

  • a Significantly different than the CVI in patients with a mean PTH <300 ng/L (P < 0.05).

  • b Significantly different than the CVI in patients who dialyzed in the morning (P < 0.05).