How are menstrual irregularities in adolescence evaluated and managed?

Evaluation and Management of Menstrual Irregularities in Adolescence

Menstrual irregularities in adolescence require a systematic evaluation to distinguish physiological immaturity from pathological conditions, with initial assessment focusing on pregnancy testing, hormonal evaluation, and identification of underlying disorders such as PCOS, hypothalamic amenorrhea, or eating disorders. 1, 2

Initial Clinical Assessment

Obtain a detailed menstrual history including age at menarche, cycle characteristics (frequency, duration, flow), last menstrual period, and associated symptoms such as pain, hirsutism, acne, or galactorrhea. 1, 2

• First action: Perform a pregnancy test to rule out pregnancy in any adolescent with missed periods or irregular bleeding. 2, 3
• Assess for signs of hyperandrogenism (hirsutism, acne) and galactorrhea, which indicate specific hormonal imbalances. 2
• Review use of hormonal contraceptives, as these commonly affect menstrual regularity. 2
• Evaluate for eating disorders, excessive exercise, weight loss, or stress—eating disorders are present in 68% of adolescents with secondary amenorrhea and 38% with oligomenorrhea. 4

A pelvic examination is NOT required before prescribing contraceptives or initiating evaluation; screening for STIs can be performed via urine or vaginal swab without speculum examination. 5

Defining Normal vs. Abnormal Patterns

Menstrual irregularity is defined as:

• Cycles <23 days (polymenorrhea) or >35 days (oligomenorrhea) 1
• Absence of bleeding for >6 months (amenorrhea) 1
• Important caveat: Irregular cycles during the first 2-3 years after menarche are often physiological due to anovulation from hypothalamic-pituitary-ovarian axis immaturity, but this does not exclude pathology requiring evaluation. 6, 7

Laboratory Evaluation

Core hormonal tests should be obtained strategically:

• FSH and LH: Measure between cycle days 3-6 with three estimations 20 minutes apart for accuracy; an LH/FSH ratio >2 suggests PCOS. 1
• Prolactin: Essential to rule out hyperprolactinemia (abnormal if >20 μg/L). 1, 2
• TSH and T4: Necessary to exclude thyroid dysfunction presenting with menstrual irregularity. 1
• Mid-luteal progesterone (day 21 of 28-day cycle): Levels <6 nmol/L indicate anovulation. 1
• Testosterone and androstenedione: Check if signs of hyperandrogenism are present; elevated levels warrant evaluation for adrenal/ovarian tumors. 1
• DHEAS: Indicated if non-classical congenital adrenal hyperplasia is suspected. 1
• Fasting glucose and insulin: Recommended if PCOS or metabolic disorders suspected. 1

Critical timing consideration: Laboratory tests should be performed without hormonal contraception for accurate assessment. 1

Common Etiologies and Their Patterns

Polycystic Ovary Syndrome (PCOS)

PCOS is the most common cause of secondary amenorrhea in adolescents, affecting 4-6% of the general female population. 2

• Characterized by hyperandrogenic chronic anovulation 2
• Laboratory findings: LH/FSH ratio >2, elevated testosterone, insulin resistance 2
• Ultrasound findings: >10 peripheral cysts (2-8 mm) with thickened ovarian stroma 1
• Low mid-luteal progesterone confirms anovulation 1

Hypothalamic Amenorrhea

Associated with weight loss, excessive exercise, or emotional stress. 2

• Laboratory findings: Low LH and low estradiol 2
• Represents hypothalamic inhibition of the gonadal axis 4
• Treatment priority: Increase caloric intake, reduce excessive exercise, and address energy availability. 8

Hyperprolactinemia

• Prolactin >20 μg/L is abnormal and can cause menstrual irregularity 2
• Requires evaluation for pituitary pathology 1

Primary Ovarian Insufficiency

• FSH >35 IU/L in women under 40 years 2
• Warrants specialist referral 1

Imaging Studies

Pelvic ultrasound (transvaginal preferred) should be performed:

• Between cycle days 3-9 if ovarian pathology is suspected 1
• To evaluate for structural abnormalities or polycystic ovaries 1, 2

Pituitary MRI is indicated if clinical features or laboratory results suggest hypothalamic-pituitary abnormalities. 1

Management Strategies

Hormonal Treatment Options

Combined oral contraceptives (COCs) provide excellent cycle control for both contraception and medical management of dysmenorrhea, heavy menstrual bleeding, and acne. 5

• Start with 30-35 μg ethinyl estradiol with levonorgestrel or norgestimate 5
• For breakthrough bleeding: If bleeding persists beyond the first 3 months, consider NSAIDs for 5-7 days or hormonal treatment with COCs/estrogen for 10-20 days. 5, 3
• Important FDA guidance: In breakthrough bleeding, rule out pregnancy and non-functional causes; if pathology is excluded, time or changing formulations may resolve the issue. 3

Depot medroxyprogesterone acetate (DMPA):

• Highly effective but causes menstrual irregularities in nearly all patients initially 5
• These irregularities typically improve over time and are less likely to cause discontinuation if patients are counseled beforehand 5
• Counseling is critical: Patients should be warned about expected menstrual changes before first injection. 5, 9

Levonorgestrel IUD:

• Effective for menstrual suppression in adolescents with complex medical conditions 5
• Particularly useful when estrogen is contraindicated 5
• Continuation rates in adolescents exceed other hormonal methods 5

Non-Hormonal Management

For heavy or prolonged bleeding:

• NSAIDs for 5-7 days are first-line treatment 5
• Address underlying nutritional deficiencies and energy availability 8

Referral Criteria

Refer to endocrinology or gynecology when:

• Amenorrhea persists >6 months 2
• Abnormal hormone levels suggest specific pathology 2
• Signs of hyperandrogenism with menstrual irregularity 2
• Suspected structural abnormalities on imaging 2
• Infertility concerns arise 1
• Signs of premature ovarian insufficiency (elevated FSH in women under 40) 1

Critical Pitfalls to Avoid

• Do not rely on a single FSH measurement for diagnosis, as levels fluctuate widely. 1
• Do not measure hormones at incorrect cycle times—timing is essential for accurate interpretation. 1
• Do not fail to consider non-reproductive causes such as thyroid disorders, eating disorders, or medication effects. 1, 4
• Do not delay evaluation assuming all irregularities are physiological—pathology can present during the post-menarchal period. 6, 7
• Do not perform unnecessary pelvic examinations—they are not required for contraceptive initiation or initial evaluation. 5