Selenoprotein P in patients on home parenteral nutrition

Background: The purpose of this study was to evaluate the use of selenoprotein P as an indicator of selenium status in patients receiving home parenteral nutrition. Methods: Adult patients (n = 38) who had been on parenteral nutrition with no addition of selenium for 3 to 216 months were included in the study. Plasma samples were analyzed for selenium, selenoprotein P, and extracellular glutathione peroxidase (eGSHPx) using fluorimetry and newly developed radioimmunoassays. Results: The mean plasma (+/- SD) eGSHPx and selenoprotein P in the patients were 1.9 +/- 1.2 mg/L and 0.7 +/- 0.4 arbitrary units, respectively, which corresponds to about 50% of the concentration measured in the plasma of the reference subjects (4.0 +/- 1.0 mg/L and 1.50 +/- 0.17 arbitrary units). The mean plasma selenium concentration was 0.5 +/- 0.4 mu mol/L, which was approximately half of the concentration measured in the healthy subjects (1.1 +/- 0.2 mu mol/L). Thirty-four (89%) and 20 (53%) patients, respectively, had selenoprotein P and eGSHPx values lower than mean - 2 SD of the reference material. The lowest values observed for selenoprotein P and eGSHPx were 3% and 2% of the reference mean. Selenoprotein P levels correlated significantly to eGSHPx (rho = 0.88, p < .0001) and plasma selenium (rho = 0.91, p < .0001). Conclusions: The positive correlations between selenoprotein P and eGSHPX and plasma selenium indicates that selenoprotein P may be used as a marker of selenium status in selenium-depleted patients.