There are no laboratory tests that make PMS identification simple. Correct diagnosis of symptoms is an essential first step for successful therapy and treatment. You can make a successful diagnosis by keeping a 'symptoms diary' over a period of at least three months. A personal diary is a far more reliable method than trying to remember when your symptoms occurred. It provides written evidence of the precise date of menstruation and the symptoms you experienced.
Charts are available from the National Association for Premenstrual Syndrome (NAPS), together with a personal symptoms checklist: