Amenorrhea (Absent Periods)

How the menstrual cycle can stop

Periods depend on a chain of signals: the hypothalamus in the brain releases GnRH, which tells the pituitary to release FSH and LH, which make the ovaries produce estrogen and progesterone and release an egg. The uterus responds by building and shedding its lining. A working outflow tract (cervix and vagina) lets blood out. A problem at any level can stop periods.

Causes by level

Primary amenorrhea

The most common causes are chromosomal problems such as Turner syndrome, hypothalamic causes (including constitutional delay of puberty), and absence or blockage of the uterus or vagina. Doctors look first at whether breasts have developed, which shows whether the body has made estrogen.

Secondary amenorrhea

After pregnancy, the most common causes are PCOS, hypothalamic amenorrhea, high prolactin and primary ovarian insufficiency.

Symptoms

The main symptom is no periods. Depending on the cause, there may also be:

• acne, oily skin, excess facial or body hair, weight gain (PCOS)
• hot flashes, night sweats, vaginal dryness (low estrogen, ovarian insufficiency)
• milky nipple discharge, headaches, vision changes (high prolactin)
• fatigue, weight change, cold or heat intolerance (thyroid)
• cyclic pelvic pain without bleeding (blocked outflow)
• delayed breast development or short stature (in primary amenorrhea)

Diagnosis

1. Pregnancy test first, always.
2. History and exam: weight and BMI, exercise, diet, stress, medicines, signs of excess androgens, breast development, a pelvic exam when appropriate.
3. Blood tests: FSH, LH, estradiol, prolactin, TSH, and testosterone if PCOS is suspected.
4. Progestin challenge in some cases: bleeding after a short course of progestin shows that estrogen is present and the outflow tract is open.
5. Imaging: pelvic ultrasound for PCOS or uterine anomalies; pituitary MRI if prolactin is high or there are neurological symptoms.
6. Karyotype (chromosome test) for primary amenorrhea with high FSH, or for ovarian insufficiency under 30.
7. Bone density scan if amenorrhea has lasted 6 months or more with low estrogen.

Treatment

Treatment targets the cause:

• Hypothalamic amenorrhea: increasing energy intake, reducing exercise intensity, restoring weight, and stress management. Periods usually return when energy balance is restored. Specialist eating disorder care when needed.
• PCOS: combined hormonal contraception or cyclic progestin to protect the uterine lining, lifestyle changes, and metformin in some people. Ovulation induction (letrozole) if pregnancy is wanted.
• High prolactin: dopamine agonists such as cabergoline, or stopping a causative medicine.
• Thyroid disease: thyroid hormone replacement or anti-thyroid treatment.
• Premature ovarian insufficiency: hormone therapy until the usual age of menopause to protect bones and heart; fertility options include donor eggs.
• Asherman syndrome: hysteroscopic removal of scar tissue.
• Outflow obstructions: surgical correction.
• Bone protection: calcium, vitamin D, weight-bearing exercise, and estrogen replacement where appropriate.

Complications

• Bone loss and osteoporosis from low estrogen, with a higher risk of stress fractures
• Infertility because ovulation is absent
• Endometrial hyperplasia in PCOS, from unopposed estrogen, which can lead to cancer if untreated
• Heart disease risk with long-term low estrogen
• Emotional distress

Frequently asked questions

What is the difference between primary and secondary amenorrhea?

Primary amenorrhea means periods never started by age 15. Secondary amenorrhea means periods that had started have stopped for at least 3 months (or 6 months if they were irregular before). The causes and tests differ somewhat between the two.

Why have my periods stopped if I am not pregnant?

Common reasons include PCOS, stress, weight loss, intense exercise, an eating disorder, thyroid problems, high prolactin, some contraceptives and medicines, breastfeeding, and early menopause. A doctor can find the cause with blood tests and sometimes an ultrasound.

Is amenorrhea dangerous?

It is a sign rather than a disease, but some causes and effects matter. Low estrogen can weaken bones, and long-term absent periods with PCOS can thicken the uterine lining. Amenorrhea lasting 3 months or more should be checked by a doctor.

Can stress stop your period?

Yes. Severe or prolonged stress, especially combined with weight loss or intense exercise, can suppress the brain hormones that drive the cycle. This is called functional hypothalamic amenorrhea. Periods usually return when stress, nutrition and exercise are rebalanced.

Can you get pregnant with amenorrhea?

It is less likely because you may not be ovulating, but it is possible, since ovulation can return before the first period. Use contraception if you do not want to conceive. If you want to get pregnant, treatment of the cause often restores ovulation.