Is there a blood test that can diagnose PMDD or is there a physical reason for having PMDD such as thyroid or pituitary issues?

History . The diagnosis of premenstrual dysphoric disorder is made on history. A good history and physical and basic labs rules our comorbidities. It is very serious as it can ruin relationships / make you say or do things you will regret terribly. There are some good treatment options today. Best wishes.