Low TSH, low normal T-4 normal T-3

[jeff605]

Asymptomatic 48 yo male caucasion.  Routine H&P.  TSH results .003.  Other labs WNL.  Retest five days later TSH .01, Free T-4 0.81 (low normal) and Free Triiodothyronine 3.1 (normal).  What are your thoughts?  What are my concerns?  What should I do next?  Am I looking at Pituitary or Thyroid?

[jeff605]

Thanks for this forum.  It is soooo helpful.  Labs drawn 10/23.  

Prolactin value     value 9.9 range 3.7-17.9
Free testosterone value 56  range 47-244
Sed Rate             value 1    range 0-15

So low sed and testosterone.  Can we rule out pituitary?  What are your thoughts?  Is something off that I need to be concerned about?  What should I do next?  We plan to repeat TSH in six weeks.

[Mark Lupo, M.D.]

Likely subclinical hyperthyroidism (ie mild hyperthyroidism) but need to consider unlikely pituitary source -- so would look at other pituitary labs like prolactin.  Would repeat labs in 6 weeks and re-evaluate esp if you have no symptoms of hyperthyroidism at this point.  The lexapro is not known to decrease TSH like this.

[jeff605]

Additional history.  I do take Lexapro 10 mg x 9 months for anxiety and Klonopin to help sleep.