lithium and hypothyroidism

LITHIUM & THE THYROID:
--not always best friends

--multiple mechanisms by which Lithium causes hypothyroidism:

• inhibits thyroid hormone release and increases TRH-stimulated TSH. 
• concentrated by the thyroid gland and inhibits iodine uptake.
• interferes with the deiodination of T4 to T3
• may have an immunostimulant effect, either by inducing or exacerbating a preexisting autoimmune disease.

--Rates of overt hypothyroidism can vary from 0 – 47% (average 10%) in people on long term lithium treatment.  


BOTTOM LINE:
--if you have a patient who is taking lithium, and you're sending off labs (lithium level, sodium/lytes, etc) for some [presumably good] reason, might be worth adding a TSH to the mix


Submitted by J. Gullo.


Reference(s): a review, another source, picture