Hello, Thank you for your question. Absence of menstruation we called amenorrhea. Amenorrhea can be a transient, intermittent, or permanent condition resulting from dysfunction of the hypothalamus, pituitary, ovaries, uterus or vagina. It is often classified as either primary (absence of menarche by age 15 years or thereafter) or secondary (absence of menses for more than three months in girl or women who previously had regular menstrual cycles or six months in women who had irregular menses). Missing a single menstrual period may not be important to assess, but amenorrhea lasting three months or more and oligomenorrhea( fewer than nine menstrual cycles per year or cycle length greater than 35 days) require investigation. The cause and diagnostic considerations for oligomenorrhea are the same as for secondary amenorrhea. There are many cause of amenorrhea first think about pregnancy. So you should do pregnancy test is recommended as a first step in evaluating any women with amenorrhea. Hypothalamic dysfunction is functional hypothalamic amenorrhea and it is very common also. It is characterized by a presumed decrease in hypothalamic GnRH secretion hormone. Risk factors, including eating disorders such as anorexia, weight loss, excessive exercise, and stress. However, some no evident. Role of leptin deficiency, genetic basis. Obesity, systemic illness, hypothlamic tumor, diabetes mellitus, celiac disease, pituitary disease, hyperprolactinemia, thyroid disease, polycystic ovary syndrome.. etc. Those etiology you need to meet a specialist. Goals of management we want to correcting the underlying cause, help you to achieve fertility, preventing complication of the disease process( eg, estrogen replacement to prevent osteoporosis). If you have hypothalamic amenorrhea: Lifestyle changes is the most helpful to make you cycle back. If you are having other problem your doctor will treat the disease that you have. You can trial lifestyle change first. If not better see your back your doctor. Hopefully they can help you. Hope I have answered your query. Let me know if I can assist you further. Best ragards, Dr. Heang Chan Raksmey, General and Family Physician.