Bipolar

Hyperthyroidism, an overactive thyroid gland, can directly cause symptoms that mimic or constitute a manic episode. This hormonal imbalance leads to significant mood and behavioral changes. 

https://scienceinsights.org/can-hyperthyroidism-cause-mania/

https://biologyinsights.com/can-hyperthyroidism-cause-mania-and-manic-symptoms/

There's information on atypicalcysticfibrosis.blogspot.com about the salt lithium connection. This is responsible for bad nose dives.

Mania is Hyperthyroidism.  Salt is adrenal support. Running the adrenals on high chronically leads to thyroid distress. The manic part is excess thyroid hormones.

These are separate issues that interact.

See Thyroid Support on this site for nutritional support for the thyroid. 

Bipolar is rooted in salt and lithium issues which impacts the adrenals and can cause thyroid issues.

You may have lithium and thyroid issues for separate reasons. But anything that chronically stresses the adrenals will lead to the thyroid running on high and if/when adrenal distress resolves, you are left with mania if the thyroid doesn't promptly ramp down.