How do I know if I have a thyroid problem and how would I know?

Syptome/tests. There many different thyroid diseases with different symptoms and presentation.Some will present with goiter(thyroid swelling in neck)while others may present with symptoms or overactive gland like palpitation, fast heart beat; weight loss.Or underactive with weight gain, and others. Diagnosis is made by blood test for the hormones and if there is a goiter with imaging like ultrasound/scan/biops.