Premenstrual syndrome, commonly called PMS, is a medical condition that has symptoms that affect many women of childbearing age. PMS can cause a variety of physical and psychological symptoms that occur just before your menstrual period.
The American College of Obstetrics and Gynecology defines PMS as "The cyclic occurrence of symptoms that are sufficiently severe to interfere with some aspects of life, and that appear with consistent and predictable relationship to the menses [menstrual period]."
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The exact cause of PMS is unknown, but it seems to be related to the fluctuating levels of hormones, including estrogen and progesterone, that occur in preparation for menstruation.
What Are the Symptoms of PMS?
There are many PMS symptoms. The number and severity of symptoms vary from woman to woman. In addition, the severity of the symptoms can vary from each month. Common PMS symptoms include:
Mood swings and/or depression
Up to 85% of menstruating women experience some of these symptoms related to their period, while only 2%-10% experience severe symptoms.
How Is PMS Diagnosed?
There is no single test to diagnose PMS. However, there are some strategies your health care provider may use to help make the diagnosis, including:
Thyroid test. 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. This can help to rule out a thyroid problem as a cause of your symptoms.
PMS symptoms diary. You may be asked to keep a diary of your PMS symptoms for two or three consecutive months, when they occur, and how long they last. By doing this, you can see if your symptoms correspond to certain times in your monthly cycle. While your symptoms may vary from month to month, a trend likely will appear after tracking them for a few months.
According to the American College of Obstetrics and Gynecology, you have PMS if:
Your symptoms occur during the last two weeks of your menstrual cycle (the two weeks before your period)
Your symptoms impair your quality of life
Your doctor has excluded other conditions that cause similar symptoms; these conditions include thyroid disease, depression, migraine headaches, irritable bowel syndrome, and chronic fatigue syndrome.