Primary amenorrhea

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"primary amenorrhea"[MeSH Terms] AND diagnosis

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Primary Amenorrhea

Definition

Primary amenorrhea is defined as:

Absence of menses by age 13 when there is no visible development of secondary sexual characteristics, OR
Absence of menses by age 15 in the presence of normal secondary sexual characteristics

Failure to begin breast development by age 13 always warrants investigation. The threshold ages were lowered by 1 year from older definitions to reflect two standard deviations above the current mean age of puberty onset.

Berek & Novak's Gynecology, p. 1856

Pathophysiology Framework

Normal menstruation requires a functioning:

Hypothalamus (pulsatile GnRH) → Anterior pituitary (FSH, LH) → Ovary (estrogen/progesterone) → Uterus/outflow tract (endometrium + patent tract)

Failure at any link causes amenorrhea. Breast development signals prior estrogen exposure, so absence of breast development = never exposed to estrogen, pointing to gonadal or central causes.

Classification by Gonadotropin Status

The WHO classifies amenorrhea into three groups:

WHO Group	Gonadotropins	Estrogen	Typical Cause
I - Hypogonadotropic hypogonadism	Low/normal FSH	Absent	Hypothalamic/pituitary failure
II - Normogonadotropic anovulation	Normal FSH	Present	PCOS, functional
III - Hypergonadotropic hypogonadism	Elevated FSH	Absent	Gonadal failure
(IV) - Hyperprolactinemic anovulation	Variable	Present	Prolactinoma

Causes of Primary Amenorrhea

Step 1: Is breast development (secondary sexual characteristics) present?

A. No Breast Development (No Estrogen Exposure)

1. Hypergonadotropic Hypogonadism (High FSH/LH) - Gonadal Failure

Condition	Key Features
Turner syndrome (45,X)	Most common cause of hypergonadotropic hypogonadism. Short stature, webbed neck, shield chest, cubitus valgus, low hairline, streak ovaries. ~30% of primary amenorrhea cases have a karyotypic abnormality
Partial X deletion / mosaicism	Variable phenotype; occasional estrogen synthesis possible
Pure gonadal dysgenesis (46,XX or 46,XY)	Streak gonads without Turner stigmata; 46,XY form = Swyer syndrome
17α-Hydroxylase deficiency	Hypertension, hypokalemia; elevated progesterone + 11-deoxycorticosterone, low cortisol/estradiol - can be life-threatening if untreated
LH/FSH receptor mutations	Rare; FSH receptor mutation common in Finland
Galactosemia	Detected on newborn screening; galactose-1-phosphate uridyltransferase deficiency causes ovarian failure
Gonadotoxic damage	Prior radiotherapy or alkylating chemotherapy (cyclophosphamide) before puberty

Key point: If FSH is elevated → get karyotype. If Y chromosome present → gonadectomy to prevent gonadoblastoma.

Berek & Novak's Gynecology, pp. 1858-1866

2. Hypogonadotropic Hypogonadism (Low/Normal FSH/LH) - Central Failure

Condition	Key Features
Constitutional (physiologic) delay	Most common cause of hypogonadotropic hypogonadism. Family history of delayed puberty; normal physical exam; consistent growth rate; self-resolving
Kallmann syndrome	Second most common hypothalamic cause. GnRH pulse generator failure + anosmia (absent olfactory bulbs). Variable inheritance (X-linked, autosomal)
CNS lesions	Craniopharyngioma, other tumors; headaches, visual field defects, DI symptoms
Hypopituitarism	Inadequate LH/FSH production
Nutritional disorders / anorexia nervosa	Weight loss → reduced GnRH pulsatility

B. Breast Development Present, Absent or Abnormal Pelvic Anatomy

(Estrogen was present; problem is the outflow tract or uterus)

Condition	Key Features
Müllerian agenesis / MRKH syndrome (Mayer-Rokitansky-Küster-Hauser)	Vaginal agenesis ± rudimentary uterus; karyotype 46,XX; normal ovaries; accounts for ~10-15% of primary amenorrhea. Associated renal anomalies in ~1/3 (agenesis, horseshoe kidney). Normal female secondary sexual characteristics
Complete Androgen Insensitivity Syndrome (CAIS)	46,XY; blind vaginal pouch; testes in labia/inguinal canal; well-developed breasts but absent/scant pubic and axillary hair (see image below); testosterone in male range; gonadectomy after puberty recommended
Transverse vaginal septum	Outflow obstruction; cyclic pelvic pain (cryptomenorrhea)
Imperforate hymen	Bluish bulging at introitus with Valsalva; cyclic pain; hematocolpos
Cervical/uterine agenesis	Rare isolated defect
Ovotesticular DSD	Ambiguous genitalia; variable karyotype (mostly 46,XX); both gonadal tissues present

Complete Androgen Insensitivity - Clinical Photograph:

Complete androgen insensitivity syndrome: well-developed breasts with paucity of pubic hair

Fig. 34-3: Well-developed patient with complete androgen insensitivity. Note the characteristic paucity of pubic hair and well-developed breasts. - Berek & Novak's Gynecology, p. 1869

C. Breast Development Present, Normal Pelvic Anatomy

(Same spectrum as secondary amenorrhea - look for functional/hormonal causes)

PCOS
Hyperprolactinemia (prolactinoma)
Primary ovarian insufficiency (POI)
Hypothyroidism
Hypothalamic functional amenorrhea (exercise, stress, weight loss)
Pituitary/hypothalamic lesions

Causes Summary (Tietz / Family Medicine)

Lower tract / outflow: Vaginal aplasia, imperforate hymen, congenital vaginal atresia

Uterine: Congenital absence (MRKH), endometritis

Ovarian: Turner/gonadal dysgenesis, 17-hydroxylase deficiency, autoimmune oophoritis, resistant ovary syndrome, PCOS

Adrenal: Congenital adrenal hyperplasia

Thyroid: Hypothyroidism

Pituitary-hypothalamic: Hypopituitarism, constitutional delay, Kallmann syndrome, nutritional disorders

Tietz Textbook of Laboratory Medicine, 7th Ed., p. corresponding section

Evaluation

Initial Workup

Step 1 - Rule out pregnancy: Serum or urine hCG first, regardless of stated sexual history.

Step 2 - Physical exam: Assess for:

Secondary sexual characteristics (breast Tanner stage)
Body habitus, height, weight
Pubic/axillary hair presence
Dysmorphic features (Turner stigmata: webbed neck, low hairline, cubitus valgus)
Anosmia (Kallmann)
Pelvic anatomy: vagina, cervix, uterus

Step 3 - Initial labs:

Test	Purpose
FSH, LH	Differentiate hypo vs. hypergonadotropic
Estradiol	Assess estrogenic status
Prolactin	Rule out hyperprolactinemia
TSH	Rule out thyroid disease
Karyotype	If FSH elevated or anatomy abnormal

Step 4 - If FSH elevated:

Karyotype to identify Turner, gonadal dysgenesis, etc.
If Y chromosome found → gonadectomy (gonadoblastoma risk)
If normal karyotype with elevated FSH → consider 17α-hydroxylase deficiency (check BP, electrolytes, serum progesterone, ACTH stimulation test)

Step 5 - Imaging:

Pelvic ultrasound or MRI: to identify presence/absence of uterus, ovaries, vagina; mullerian anomalies
If no uterus found on ultrasound → karyotype to differentiate MRKH (46,XX) from CAIS (46,XY)
Renal ultrasound / IVP: if mullerian anomaly found (rule out associated renal malformations)
MRI brain: if CNS lesion suspected (visual symptoms, headaches, DI)

For Turner syndrome specifically:

Echocardiogram every 3-5 years (coarctation of aorta in up to 30%)
Thyroid function yearly
Assess for hearing loss, renal malformations, diabetes, hypertension
Cardiac MRI important component of cardiac evaluation
Berek & Novak's Gynecology, pp. 1869-1876

Key Diagnostic Algorithm

Primary Amenorrhea
        │
        ├─ Breast development absent?
        │       │
        │       ├─ FSH/LH high → Hypergonadotropic hypogonadism
        │       │       → Karyotype
        │       │       → Turner, gonadal dysgenesis, enzyme deficiency
        │       │
        │       └─ FSH/LH low → Hypogonadotropic hypogonadism
        │               → Constitutional delay, Kallmann, CNS lesion
        │
        └─ Breast development present?
                │
                ├─ Abnormal pelvic anatomy (no uterus/vagina)
                │       → Karyotype
                │       → 46,XX = MRKH
                │       → 46,XY = CAIS (no pubic hair)
                │
                └─ Normal pelvic anatomy
                        → FSH, prolactin, TSH
                        → Treat like secondary amenorrhea
                        → PCOS, hyperprolactinemia, functional

Treatment Principles

Etiology	Management
Turner syndrome / gonadal failure	Hormone replacement therapy (estrogen + progestogen) to induce puberty, maintain bone density, and reduce cardiovascular risk
Y-containing gonadal dysgenesis	Gonadectomy (gonadoblastoma/germ cell tumor risk) + HRT
CAIS	Vaginoplasty for functional vagina; gonadectomy after puberty (or watchful waiting with surveillance); psychological support
MRKH	Progressive vaginal dilation (Frank method) as first-line; surgical vaginoplasty (McIndoe) if dilation fails; uterine transplant for fertility in select cases
Imperforate hymen / vaginal septum	Surgical incision/resection
Constitutional delay	Reassurance; low-dose estrogen may be given to induce puberty if causing psychosocial distress
Kallmann / hypogonadotropic hypogonadism	Pulsatile GnRH or exogenous gonadotropins for fertility; HRT for feminization
Hyperprolactinemia (prolactinoma)	Dopamine agonist (cabergoline, bromocriptine)
Hypothyroidism	Levothyroxine
Hypothalamic functional (weight/exercise/stress)	Treat underlying cause; nutritional rehabilitation

Health Implications of Untreated Amenorrhea

Bone loss/osteoporosis - from chronic estrogen deficiency
Cardiovascular risk - especially in Turner syndrome
Infertility
Psychological impact - particularly in MRKH and AIS patients (identity, sexuality)
Malignancy risk - gonadoblastoma in Y-containing streak gonads

"Absent or irregular menses may be an indication that a woman has a medical condition that can affect her overall health. The health implications can vary depending on the etiology of the amenorrhea. Therefore, a cause for amenorrhea should be established whenever possible." - Berek & Novak's Gynecology, p. 1857

Sources: Berek & Novak's Gynecology (9th Ed.); Tietz Textbook of Laboratory Medicine (7th Ed.); Textbook of Family Medicine (9th Ed.); Harrison's Principles of Internal Medicine (22nd Ed., 2025)

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