ISSN:
1420-9071
Keywords:
Phenylketonuria
;
selenium
;
glutathione peroxidase
;
thyroid hormones
;
type I 5′-deiodinase
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Abstract Phenylketonuric (PKU) subjects have a limited supply of selenium (Se) in their phenylalanine-restricted diet. A Se repletion (1 μg Se/kg/day)/depletion study was conducted in PKU children to determine the effect of Se on thyroid function parameters. The initial plasma Se concentration (mean±SD: 0.26±0.12 μmol/L, p〈0.00003, n=10) and glutathione peroxidase (GSH-Px) activity (140±58 U/L, p〈0.00003, n=10) were significantly lower compared to agematched controls. After 14 weeks of supplementation, the plasma Se concentration (mean ±SD: 0.74±0.20 μmol/L) normalized (normal range: 0.57–1.15 μmol/L, mean ±SD: 0.76±0.13 μmol/L, n=32) and remained stable thereafter during repletion. Plasma GSH-Px activity reached normal values after 18 weeks of supplementation (312±57 U/L; normal range: 238–492 U/L, mean ±SD: 345±54 U/L, n=32) and increased significantly for up to eight weeks thereafter (332±52 U/L). Individual and mean thyroid parameters were initially normal in all cases. The mean concentrations of plasma thyroxine (T4: p〈0.025), free T4 (FT4: p〈0.01) and reverse triiodothyronine (rT3: p〈0.005) decreased to 75% of their initial value within three weeks of Se supplementation and remained stable thereafter, within a normal physiological range during selenium supplementation. They increased back to their initial values three weeks (T4: p〈0.05, FT4: p〈0.05) and six weeks (rT3: p〈0.025) respectively, after the end of the supplementation. In conclusion, Se supplementation modifies thyroid function parameters in Se-deficient PKU subjects most likely by an increase in activity of type I 5′-deiodinase (5′-DIase I).
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01944738
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