Amenorrhea Diagnosis What To Do

Not having periods, that is, amenorrhea, is less a disease name in itself than a result indicating that a signal has gone awry somewhere in the body. In the clinic, the causes for those who come saying "I have had no period for several months" span a very wide range, from pregnancy to hormonal imbalance and, rarely, structural abnormality. Periods become a subject for review when the volume is too little or too much, when the cycle is too short or too long, or when they are erratic. In this article, I have organized how to view, in broad terms, the case of "not having periods at all," along with the criteria for distinguishing primary from secondary amenorrhea and the flow of evaluation.

Menstruation is not simply a matter of the uterus alone but an event that occurs with four organs connected like a chain. When the hypothalamus in the head sends a signal, the pituitary gland secretes hormones, those hormones stimulate the ovaries to cause ovulation and secretion of estrogen and progesterone, and finally the endometrium thickens and then sheds, becoming menstrual blood. In medicine, this pathway is called the hypothalamic-pituitary-ovarian axis, or the HPO axis in English.

The key point is that a fault in even one of these four stages results in the same outcome of "not having periods." So even with the same amenorrhea, the cause varies widely, and it is hard to tell which stage is the problem from the outwardly apparent symptoms alone. This is precisely why the American College of Obstetricians and Gynecologists (ACOG) and the American Society for Reproductive Medicine (ASRM) recommend approaching amenorrhea evaluation in stages. Only by carefully working out at which level the signal was cut off can an accurate diagnosis be reached.

Primary amenorrhea refers to a state in which menstruation has never been experienced. The criteria are divided into two. When secondary sexual characteristics such as breast development have appeared normally but there is no menarche by age 15, or when there are no secondary sexual characteristics themselves and there is no menarche by age 13. The ASRM's 2024 Committee Opinion on amenorrhea evaluation presents these age criteria as the starting point for evaluation.

In primary amenorrhea, genetic and anatomical causes must be examined together. According to reports, gonadal dysgenesis, and among these Turner syndrome related to X chromosome abnormality, accounts for a considerable proportion, and Müllerian agenesis, in which the uterus or vagina is congenitally not formed, is also cited as a common cause. In addition, constitutional delay in which puberty itself starts late, and hormone deficiency at the hypothalamic and pituitary stage, are also subjects for differentiation.

An adolescent having a later menarche than peers is not necessarily a disorder, but if the above age criteria have been exceeded or the progression of secondary sexual characteristics seems to have stopped, it is good to check without delay. This topic is covered in more detail in disorders that adolescents whose menarche has not begun should consider, so please refer to it together.

Secondary amenorrhea is a state in which periods have stopped in someone who previously had menstruation. For those who were usually regular, evaluation begins when there has been no period for 3 months or more; for those who were originally irregular, when there has been no period for 6 months or more. The same applies when a pattern of skipping much longer than one's own cycle repeats.

Skipping a period once or so can happen to anyone, so in many cases a test is not necessarily needed. However, if periods are repeatedly absent, if there are only nine or fewer periods a year, or if the menstrual cycle lengthens to 35 days or more, it is worth taking a look once. In the clinic, quite a few people put off these signals because they are busy and come in belatedly, or pass the time unaware that it is abnormal and have it found by chance.

The first thing, and one that must always be considered, in secondary amenorrhea is pregnancy. Both ACOG and ASRM emphasize confirming pregnancy status before other tests. Only after pregnancy is ruled out does the stepwise evaluation of hormones and structure carry meaning.

Excluding pregnancy, the most commonly found causes in secondary amenorrhea are a hypothalamic-stage problem, functional hypothalamic amenorrhea, and polycystic ovary syndrome (PCOS). Although the two may look similar in outcome, their mechanisms are nearly opposite.

Functional hypothalamic amenorrhea is a state in which the hypothalamic signal itself is suppressed by excessive stress, rapid weight loss, or excessive exercise, halting ovulation. The Endocrine Society (2017) treats this diagnosis as a "diagnosis of exclusion" to be made after ruling out other causes. Conversely, polycystic ovary syndrome is an endocrine disorder in which ovulatory dysfunction and androgen-related findings appear together, and the 2023 International PCOS Guideline organizes the diagnostic criteria and evaluation methods. Behind weight gain and amenorrhea appearing together are such hormonal changes, and this connection is explained separately in the connection between weight gain and amenorrhea.

Polycystic ovary syndrome can manifest not only as menstrual irregularity but also in various forms such as acne and infertility, so it is hard to tie it to a single keyword. More detailed content can be found in understanding polycystic ovary syndrome.

The main course of amenorrhea evaluation is history taking, physical examination, blood tests, and imaging tests. Rather than an answer coming from a single test, it is closer to a process of narrowing down which level of the HPO axis is the problem.

After first confirming pregnancy status, the hormone profile is examined. Thyroid function (TSH), prolactin, follicle-stimulating hormone (FSH) and luteinizing hormone (LH), and estradiol are the basic items, and depending on the direction in which these values are skewed, it is divided into whether it is a hypothalamic or pituitary problem or a problem of the ovary itself. Androgen levels or chromosome testing are added selectively according to the clinical picture. Pelvic ultrasound shows the structure of the uterus and ovaries and the endometrial thickness together, helping set direction early in the evaluation.

It is normal for test items to differ from person to person. Which tests are needed is determined by symptoms and history, and this part is worked out with cases in what tests are needed when there is no period.

Not having periods does not mean it is all menopause. One misconception often heard in the clinic is the question "my periods have become infrequent, so isn't it menopause now?" but the two should be viewed separately. Natural menopause is a physiological change in which periods permanently stop as ovarian function is exhausted with age, whereas amenorrhea broadly refers to a state in which periods are absent temporarily or persistently due to various other causes.

In particular, a decline in ovarian function at a young age requires separate evaluation. Premature ovarian insufficiency, in which ovarian function is lost before age 40, is handled differently from simple menstrual irregularity and is diagnosed by looking at hormone levels (especially an FSH rise) and symptoms together. This topic is further covered in premature menopause, can it be prevented and treated and if there is no period, is it all menopause. If you usually have a pattern of irregular menstruation, it is safer to identify the cause before concluding it is menopause.

What plays an unexpectedly large role in amenorrhea evaluation is the patient's own record. When your last period was, how the cycle has changed, and whether there have been accompanying symptoms become clues for deciding which test to do first. In my clinical experience, an accurate menstrual history is the easiest tool to reduce unnecessary tests and approach the cause quickly.

These days, there are good apps that record the menstrual cycle, so you can use them without burden. Just keeping a steady record of the dates lets you see at a glance "after how many months you had a period" and "whether the cycle is gradually lengthening," which greatly helps in the consultation. If it is hard to judge for yourself whether it is abnormal or normal, rather than worrying alone, it is good to get a consultation through women's health care.

If your period has stopped for a long time or the pattern has changed from usual, please do not put off that signal. Just knowing the cause accurately greatly reduces vague anxiety. If you have questions, please ask online about amenorrhea and menstrual changes.

Written by Lee Dong-hee, Director · OB-GYN specialist · See physician profile

First published December 1, 2023 · Last reviewed May 30, 2026

References: American Society for Reproductive Medicine (ASRM) Committee Opinion on Amenorrhea Evaluation (2024), American College of Obstetricians and Gynecologists (ACOG), American Academy of Family Physicians (AAFP) Diagnostic Approach to Amenorrhea (2019), Endocrine Society Functional Hypothalamic Amenorrhea Guideline (2017), International PCOS Guideline (2023)

This article is intended to provide general health information and does not replace individual diagnosis or treatment. If you have symptoms, please consult through a medical visit.