When elevated, aldosterone works to re-absorb and retain sodium while wasting potassium in the process.
This loss of potassium actually causes your arteries to constrict, increasing your blood pressure.
Elevated aldosterone also promotes both inflammation and edema (water retention), and suppresses your metabolism.
All of these further promote hypothyroidism.
To regulate both water balance and blood pressure, you must regulate aldosterone.
Aldosterone rises in response to many things including:
Sodium Loss
Elevated Parathyroid Hormone (via low calcium)
Hypoglycemia
Estrogen Dominance
Elevated Serotonin
Bacterial Endotoxin