My pdocs have all said that thyroid issues can cause Bipolar like symptoms so when they suspect Bipolar it is always a good idea to rule out anything else like a Thyroid condition. Being Hypothyroid and make you lethargic and depressed and being hyperthyroid can make you all amped up but uncommonly being hypothyroid can also cause what looks like manic or psychotic looking issues or can push an already manic sensitive situation in a worse situation. This is just the info that I have gotten from my docs. I am sure there is different info out there.