What is the workup for irregular menses (irregular menstrual cycles) in pediatric patients?

Workup for Irregular Menses in Pediatric Patients

Begin with a pregnancy test, followed by hormonal assessment (FSH, LH, TSH, prolactin, estradiol), and pelvic ultrasound when clinical features suggest ovarian pathology. 1, 2

Initial Clinical Assessment

Obtain a detailed menstrual and medical history focusing on:

• Age of menarche and duration of irregularity 1
• Weight changes, eating patterns, and exercise habits to screen for Female Athlete Triad or disordered eating 1
• Medication use, particularly hormonal contraceptives, antipsychotics, and antiepileptics 1
• Symptoms of galactorrhea, hirsutism, or acne suggesting hyperandrogenism 1, 2
• Calculate BMI, as obesity is associated with PCOS and menstrual irregularities 1

Physical examination should include:

• Tanner staging of breast and pubic hair development 1
• Thyroid examination for enlargement or nodules 1
• Assessment for signs of hyperandrogenism (hirsutism, acne) 2

Laboratory Testing Algorithm

First-line tests (perform in all patients):

• Pregnancy test - must be performed first to exclude pregnancy 1, 2
• FSH and LH - measure between days 3-6 of menstrual cycle when possible; three measurements 20 minutes apart for accuracy 2
• TSH and T4 - to exclude thyroid dysfunction 2
• Prolactin - to rule out hyperprolactinemia 2
• Estradiol - measure during early follicular phase to establish baseline ovarian function 2

Second-line tests (based on clinical presentation):

• Testosterone and androstenedione - if signs of hyperandrogenism present 2
• DHEAS - if non-classical congenital adrenal hyperplasia suspected 2
• Progesterone - measure mid-luteal phase (day 21 of 28-day cycle); levels <6 nmol/L indicate anovulation 2
• Fasting glucose and insulin - if metabolic disorders or PCOS suspected 2

Key interpretation points:

• LH/FSH ratio >2 suggests PCOS 1, 2
• Elevated FSH (>40 mIU/mL) indicates primary ovarian insufficiency; requires confirmation with repeat FSH 4 weeks later 1
• Low progesterone (<5 ng/mL) throughout cycle suggests anovulation 1

Imaging Studies

Pelvic ultrasound indications:

• Clinical features or hormonal tests suggest ovarian pathology 1
• Perform transvaginal ultrasound (more sensitive than transabdominal) between days 3-9 of cycle 2
• Assess endometrial thickness: thin (<5 mm) suggests estrogen deficiency; thick (>8 mm) suggests chronic anovulation with unopposed estrogen 1

• 10 peripheral cysts (2-8 mm diameter) with thickened ovarian stroma suggest polycystic ovaries 2

Pituitary MRI - indicated if clinical features or laboratory results suggest hypothalamic-pituitary abnormalities 2

Referral Criteria

Refer to pediatric endocrinology/gynecology for:

• No signs of puberty by age 13 years 3
• Primary amenorrhea by age 16 years 3
• Failure of pubertal progression 3
• Menstrual cycle dysfunction suggesting premature ovarian insufficiency 3
• Persistent abnormal hormone levels or severe menstrual irregularities 2
• Concern for eating disorder or Female Athlete Triad 1
• Signs of premature ovarian insufficiency (amenorrhea with elevated FSH in patients under 40) 2

Special Considerations for Cancer Survivors

For survivors treated with gonadotoxic chemotherapy or ovarian radiation:

• Monitor growth (height) and pubertal development (Tanner stage) at least annually 3
• FSH and estradiol recommended for those presenting with menstrual cycle dysfunction 3
• Discontinue hormone replacement therapy prior to laboratory evaluation when applicable 3
• AMH may be reasonable in conjunction with FSH and estradiol for patients ≥25 years 3

Common Pitfalls to Avoid

• Do not rely on single FSH measurement - levels fluctuate significantly, particularly during perimenopause 2
• Do not measure hormones at incorrect cycle times - timing is critical for accurate interpretation 2
• Do not assume all irregular menses in adolescents are physiologic - pathology requiring treatment may be present even in early post-menarchal years 4, 5
• Do not perform hormonal testing while patient is on hormonal contraception - discontinue for accurate assessment 2
• Do not overlook non-reproductive causes - thyroid disorders, medications, stress, and weight changes affect hormone levels 2
• Do not delay evaluation in patients with disordered eating - assess for low bone density 1