Thyroid Hormone Treatment and Uric Acid Level


Question

Dear Doctor

I have a patient with benign thyroid cyst on suppressive therapy with 150 micrograms thyroxine . H e r thyroid function tests on this are :

Free T 4 23.2pmol/l range10-25

freeT3 6.8pmol/l range 3.3-7.2

S-TSH <0.01 0.2-0.4

Her uric acid is very low at 86micromols/l, range 140-390.

She also has a hip bursitis and shoulder capsulitis, but ESR is normal, RF normal, and ANF normal. Her diet is apparently normal. Using a MIRENA coil .

Is there any relation of the low uric acid to the thyroid treatment

Regards

Dr Tom Scade, MbChBBSC(Hons)FRCP(G)MRCGP(UK)

Emirates Clinic , PO Box 26777, Dubai , UAE

e-mail tom.scade@emirates.com

Response

There is no description that I can find of subnormal serum uric acid associated with thyroid hormone excess. There is a useful section on hypouricemia in the Harrison text, 14th Edn, p2165. Can you be sure that none of the medications used for the shoulder complaint have a uricosuric component ?

One other comment. I wonder about the wisdom of using suppressive T4 therapy in a woman who may be at risk of osteoporosis, when the benefit of such therapy in managing benign cysts is less than convincing. Subclinical thyrotoxicosis as a result of suppressive T4 certainly seems to decrease bone density ( see Wesche et al J Clin Endocrinol Metab 2001; 86:998-1005)

Regards, Jim Stockigt