MRI

[thyroida]

Dear Dr. Lupo, my Endocrinologist is recommending Pituatary MRI.  Both TSH and Free numbers have been decreasing (latest labs TSH 1.86 [range .4-4.5], FT3 2.23 [range 2.3-4.2], FT4 .7 [range .8-1.8]).  What would cause both TSH and Free numbers to drop, shouldn't TSH rise with falling FT3/FT4?   Do you feel the MRI is necessary based on these labs?

[Mark Lupo, M.D.]

ie, the lab variation is likely a normal variant and not clinically significant.

[thyroida]

Thanks for your response.   Can you please clarify what you mean by normal- the lab results are normal, or the change in Free and TSH values appear normal?

[Mark Lupo, M.D.]

This is likely normal, but pituitary MRI is a good way to exclude any pituitary mass or other problem.  Other options would be to recheck T3 and T4 with a different lab.