Sodium selenite therapy and thyroid-hormone status in cystic fibrosis and congenital hypothyroidism

Abstract

The effectiveness of a peroral sodium selenite therapy (115 μg Se/m² BSA/d) administered to cystic fibrosis patients (n=32) could after three months be identified in a significant serum selenium increase (0.69→0.96 μmol/L), a significant malondialdehyde decrease (2.72→1.64 μmol/L), as well as in a significant serum vitamin E increase (4.31→5.72 μg/mL) Parallel to that, a serum T₃ increase as well as a highly significant decrease in the serum T₄/T₃-ratio were found, too, which point to improved peripheral T₄→T₃ conversion during selenium medication. Type-I-iodothyronine-5′-deiodinase has recently been identified as a specific selenoenzyme.

In the case of congenital hypothyroidism (n=37) application of sodium selenite in the above specified dosage yielded a mean serum selenium increase (0.87→1.12 μmol/L), a not significant T₃ increase (2.57→2.61 nmol/L) as well as a not significant TSH decrease (5.34→4.49 mIU/L) without an expected T₄ decrease. With the serum lipids, however, a lowering of total cholesterol (4.85→4.53 mmol/L) simultaneous with a mean increase in HDL-cholesterol (1.52→1.66 mmol/L) as well as a decrease in LDL-cholesterol (2.93→2.52) could be observed. We view the reduction of the atherogenic serum lipid constellation in the course of selenium medication as an expression of increased thyroid-hormone efficacy.

Apart from an improvement of the antioxidant status a stimulation of thyroid-hormone efficacy owing to increased T₄→T₃ conversion is also noteworthy in sodium selenite medication.