11
Unanswered Questions
UNANSWERED QUESTIONS
(Areas Needing Further Research)
Î The significance of perturbations in serum triiodothyronine
concentrations within the reference range or of mildly low serum
triiodothyronine concentrations is unknown.
Î Patients with hypothyroidism treated with levothyroxine to achieve
normal serum TSH values may have serum triiodothyronine
concentrations that are at the lower end of the reference range, or even
below the reference range. The clinical significance of this is unknown.
Î There are specific instances in which there appears to be discordance
between the thyroid status of the pituitary gland, as reflected by the
serum TSH, and the thyroid status of other tissues as indicated by
various biomarkers. The clinical significance of this is not known.
Î Specific polymorphisms in the deiodinases are consistently associated
with very small changes in serum thyroid hormone levels. Insufficient
data exist to draw any conclusion about the clinically relevant effects
of deiodinase or transporter polymorphisms on tissue thyroid hormone
levels.
