Hi,
I'm new here and just so I can strongly recommend getting the thyroid checked, and NOT just TSH, but also for T4, T3 and antibodies. Autoimmune thyroiditis is a possible cause for depression/bipolar disorder.
I spent years on different anti-depressants, mood stabilizers, and anti-anxiety meds. Psychiatrists always asked about my thyroid, but it was always fine because the doctors generally just do a test for TSH levels. Finally, I went to an endocrinologist who tested to T3 and T4 levels, as well as antibodies. My TSH levels were in the realm of "normal". The antibodies showed evidence of hypothyroidism. Within weeks of thyroid medication, I feel great. My depression is going away, my anxiety and mood swings are less, and I've lost weight.
PLEASE ask for thyroid tests, including TSH, T4, T3 and antibodies tests. A "functional" TSH level is less than 3, while the "normal" range is up to 5.5. If you have a TSH level of over 3, and if you have high or low T4 or T3, or the presence of antibodies, talk to your doctor about your thyroid. It may save you years of struggle!