thyroid cyst

[double0]

I have a 1.4 cm complex cyst on my left lobe. I have classic signs of hyperthyroid is what my doc and endo have said. However. all my blood work (TSH, T3, T4, globulin anti. and myoclin anti.) and up take scan are normal.  Is it possiable that the cyst can cause symptoms of fatigue, rapid heart rate (at times), feeling cold or hot (sweating)?
They are going to byopsie it to rule out cancer... but aren't the chances of it being cancer like almost none?
I am 37 yrs old, female, 5'1", 98 lbs. with 3 young children.
Also by looking at my med records from 1999 my TSH was .54 and now are 1.30.even though both of these are normal levels is it possiable for ME (my body) since level elevated could cause symptoms?
Thanks and I hope you can help me with these questions!
Double0

[santhul]

Dear Double,
Please get your FNAB done as soon as possible. also a nuclear scan if possible.
since your thyroid levels are normal, there can not be any symptoms.
but do not rule out the possibility of carcinoma

[Mark Lupo, M.D.]

The cyst will not cause these symptoms unless it is producing thyroid hormone -- which based on normal TSH, etc - it is not.  A TSH of 0.54 and 1.3 are both normal.

The chance of caner is 5-10% and FNA biopsy is the next step.  I-123 scanning does not add any useful clinical information at this point.

The fatigue and rapid heart rate are not likely due to a thyroid problem.