Anyone ever had an underactive thyroid?!

Anyone ever had an underactive thyroid?

I take litium and have haven't been feeling quite normal (who is to define normal, though). I've been researching some and think I might have an underactive thyroid possibly caused by the lithium I take. Weight gain (feeling so bloated), tiredness, moodyness, depression, tight tender skin on thighs and legs... What were some of your symptoms?

I have an underactive thyroid, but I don't know what caused it. Symptoms of hypothyroidism include; weight gain, IBS with constipation, cold feet &/or hands, low body temp, dry thinning hair, dry skin, fatigue, muscle and joint aches, depression, headaches, sensitivity to light, slow heart rate, low blood pressure, ridged fingernails with no moons, and fertility issues.

Testing is by blood work. It must be done first thing in the morning or it could stop a diagnosis. Basically a TSH over 2.0 shos that the thyroid gland is slowing down. If possible get a TSH, free t4, free t3, and antibody test.