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

The effectiveness of a peroral sodium selenite therapy (115 micrograms 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 mumol/L), a significant malondialdehyde decrease (2.72-->1.64 mumol/L), as well as in a significant serum vitamin E increase (4.31-->5.72 micrograms/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 mumol/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.