I too found out I had a thyroid issue after being diagnosed with Low T. Your TSH level is the typical indicator. Traditionally, anything below 5.0 was considered normal. But more recently, studies have shown that TSH levels alone are not a good enough indicator and you must look at the symptoms as well. [Read up on HypoTh symptoms and see if that fits you.]
The new range is anything above 2.0, in conjunction with symptoms can be an indicator of thyroid inefficiencies.
Unfortunately, almost all docs are unaware of this and you may need to educate yours. Read the study from the following link:
http://www.metabolism.com/2009/06/26...hypothyroidism
Also check out,
http://www.stopthethyroidmadness.com/ for *lots* of good informative info.
Best of luck.