Antioxidant and thyroid hormone status in selenium-deficient phenylketonuric and hyperphenylalaninemic patients.
BACKGROUND
Subjects consuming protein-restricted diets, such as patients with phenylketonuria (PKU) or milder hyperphenylalaninemias (HPAs) are at risk of selenium deficiency. Selenium is a cofactor of the antioxidant enzyme glutathione peroxidase and of the thyroid hormone converting enzyme thyroxine deiodinase.


OBJECTIVE
Our goal was to investigate the effects of low plasma selenium on antioxidant and thyroid hormone status.


METHODS
We assessed plasma selenium, plasma total antioxidant status and the individual components thereof, erythrocyte antioxidant status, and plasma thyroid hormones in 24 PKU and 10 HPA patients and in 42 age-matched control subjects.


RESULTS
Selenium was significantly lower in both PKU and HPA patients than in control subjects and the PKU patients had lower values than did the HPA patients. Total antioxidant status was lower in both patient groups than in the control group, whereas alpha-tocopherol, albumin, and uric acid were not significantly different among groups. Plasma selenium correlated well (r = 0.76) with erythrocyte glutathione peroxidase. PKU patients had lower glutathione peroxidase activity than did HPA patients and control subjects and lower glutathione concentrations than did control subjects. Both patient groups had lower superoxide dismutase activity than did control subjects. Free triiodothyronine was higher in both patient groups than in control subjects, whereas free thyroxine was higher in the PKU patients only. Free thyroxine and reverse triiodothyronine were inversely correlated with selenium.


CONCLUSIONS
Supplementation with selenium seems to be advisable for patients consuming diets low in natural protein.
van Bakel
M M
MM
University Hospital, Children's Clinic, Division of Metabolic Diseases, and the Chemical Central Laboratory, University of Bern, Bern, Switzerland. marit.vanbakel@dkf2.unibe.ch
Printzen
G
G
Wermuth
B
B
Wiesmann
U N
UN
D000293:Adolescent; D000328:Adult; D000975:Antioxidants / Q000032:analysis*; D002648:Child; D002675:Child, Preschool; D018753:Diet, Protein-Restricted / Q000009:adverse effects*; D005260:Female; D019803:Glutathione Disulfide / Q000097:blood; D005979:Glutathione Peroxidase / Q000097:blood; D005980:Glutathione Reductase / Q000097:blood; D005982:Glutathione Transferase / Q000097:blood; D006801:Humans; D007223:Infant; D008297:Male; D010661:Phenylketonurias / Q000097:blood / Q000178:diet therapy*; D012643:Selenium / Q000097:blood / Q000172:deficiency*; D012709:Serum Albumin / Q000032:analysis; D013054:Spectrophotometry, Atomic; D013482:Superoxide Dismutase / Q000097:blood; D013974:Thyroxine / Q000097:blood*; D014284:Triiodothyronine / Q000097:blood*; D014527:Uric Acid / Q000097:blood; D014810:Vitamin E / Q000097:blood
D000975:Antioxidants; D012709:Serum Albumin; D014284:Triiodothyronine; D014810:Vitamin E; D014527:Uric Acid; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D005980:Glutathione Reductase; D005982:Glutathione Transferase; D012643:Selenium; D013974:Thyroxine; D019803:Glutathione Disulfide