1 Thyroid test. 2  Because thyroid disease is common in women of childbearing age, and some of the symptoms of PMS -- such as weight gain -- are similar to symptoms of thyroid disease, a test may be done to evaluate how well your thyroid is functioning.3  This can help to rule out a thyroid problem as a cause of your symptoms. Thyroid test. 2  Because thyroid disease is common in women of childbearing age, and some of the symptoms of PMS -- such as weight gain -- are similar to symptoms of thyroid disease, a test may be done to evaluate how well your thyroid is functioning. 3  This can help to rule out a thyroid problem as a cause of your symptoms.