Amenorrhea and galactorrhea: primary, secondary and four compartments
- Topic
How to think about absent periods and milky nipple discharge: first rule out pregnancy, then look for the level where the problem lies.
See it in 3D: Hypothalamus · Pituitary gland · Ovaries · Body of uterus · Endometrium · Cervix · Vagina · Mammary gland lobes
What it is
Amenorrhea is the absence of menstruation. It is primary when periods have never started and secondary when they stop in someone who used to menstruate. Causes are sorted into four compartments: the outflow tract and uterus, the ovary, the pituitary and the hypothalamus. Galactorrhea, milk secretion outside pregnancy and breastfeeding, often travels with amenorrhea because a high prolactin level suppresses the reproductive axis.
Key facts
- Primary amenorrhea: no periods by about age 15 with normal breast development, or by about 13 without breast development.
- Secondary amenorrhea: no periods for three months after regular cycles, or six months after irregular cycles.
- Pregnancy is the most common cause of secondary amenorrhea and is always ruled out first.
- The exam looks at height, weight and body mass index, breast development (Tanner stage), signs of androgen excess, the thyroid, nipple discharge, the visual fields and the genitals.
- Milky discharge from both breasts suggests galactorrhea; bloody discharge from one duct is a different problem and needs a breast workup.
The four compartments of amenorrhea
| Compartment | Examples | Bedside clues |
|---|---|---|
| I. Outflow tract and uterus | Müllerian agenesis, imperforate hymen, transverse vaginal septum, intrauterine adhesions (Asherman syndrome) | Normal breasts with absent or blind vagina; cyclic pelvic pain; history of uterine curettage |
| II. Ovary | Turner syndrome and other gonadal dysgenesis, primary ovarian insufficiency, polycystic ovary syndrome | Short stature and webbed neck; hot flushes; hirsutism, acne and acanthosis |
| III. Pituitary | Prolactinoma and other adenomas, postpartum pituitary necrosis (Sheehan syndrome) | Galactorrhea, headache, loss of the outer visual fields; failure to breastfeed after a postpartum hemorrhage |
| IV. Hypothalamus | Low energy intake, intense exercise, eating disorders, stress, Kallmann syndrome | Low weight, bradycardia, low blood pressure; loss of smell in Kallmann syndrome |
Clinical notes
- Galactorrhea causes: prolactinoma, dopamine-blocking drugs (antipsychotics, metoclopramide), primary hypothyroidism, chest wall injury or repeated nipple stimulation, and kidney or liver failure.
- Hypothyroidism can raise prolactin and disturb cycles, so thyroid function is part of the first workup.
- Polycystic ovary syndrome is the most common cause of irregular cycles with signs of androgen excess.
- In primary amenorrhea, breast development separates outflow and androgen-insensitivity causes (breasts present) from ovarian or central causes (breasts absent).
- Virilization, visual field loss, loss of smell, spontaneous milky discharge and marked weight change are warning signs.
In the lab
- First step: a pregnancy test (beta-hCG).
- Then prolactin, TSH and FSH; a high FSH points to the ovary, a low or normal FSH to the pituitary or hypothalamus.
- Testosterone and DHEA sulfate if there are signs of androgen excess.
- Pelvic ultrasound in primary amenorrhea to confirm a uterus; pituitary MRI when prolactin is high or the visual fields are affected.
Test yourself
Think of the answer, then tap the question to see it.
What is the first test in any woman of reproductive age with amenorrhea?
A pregnancy test, because pregnancy is the most common cause of secondary amenorrhea.
What does a high FSH level mean in amenorrhea?
The ovary is failing (for example primary ovarian insufficiency or Turner syndrome), so the pituitary is pushing harder.
What are three causes of galactorrhea besides prolactinoma?
Dopamine-blocking drugs such as antipsychotics or metoclopramide, primary hypothyroidism and chest wall stimulation or injury; kidney failure is another.
Which compartment does Asherman syndrome affect?
The uterus (compartment I): intrauterine adhesions, usually after curettage, prevent the endometrium from shedding.
Connections
See it in 3D8
The structures of Durgical's 3D anatomy where it is found.
Educational content on the clinical exam; it is learned and practised under supervision. It does not replace assessment by a health professional and is not for self-diagnosis.
Sources: Amenorrhea (MSD Manual Professional Edition, 2024); Prolactinoma (MSD Manual Professional Edition, 2024).
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Representative model, for educational purposes only.