What is the best course of action for a 14-year-old female patient experiencing irregular menses (menstruation)?

Management of Irregular Menses in a 14-Year-Old

In a 14-year-old with irregular menses, reassurance and observation are appropriate for the first 2-3 years post-menarche, as cycles ranging 21-45 days are physiologically normal during adolescent development, but a focused evaluation to exclude pregnancy, thyroid dysfunction, and hyperprolactinemia should be performed if irregularity is severe or persistent. 1

Initial Clinical Assessment

The evaluation should focus on specific red flags rather than routine screening:

• Menstrual pattern documentation: Record cycle length (normal adolescent range: 21-45 days, wider than the adult 21-35 day range), duration of bleeding, and flow volume 1
• Signs of androgen excess: Assess for hirsutism, acne, or male-pattern hair distribution that might suggest polycystic ovary syndrome (PCOS), which affects 4-6% of reproductive-age women and is a frequent cause of menstrual disorders in adolescents 2, 3
• Weight and nutritional status: Document BMI, recent weight changes, athletic activity level, and eating patterns to identify functional hypothalamic amenorrhea 1
• Sexual activity status: Determine if pregnancy testing is indicated 1

Diagnostic Workup

The initial laboratory evaluation should be selective, not comprehensive:

• Mandatory tests include pregnancy test (beta-hCG) if sexually active or clinically indicated, thyroid function tests (TSH and free T4), and prolactin level, as these represent the most common endocrine causes of menstrual irregularity in adolescents 1
• Additional hormonal testing (LH, FSH, mid-luteal progesterone) should be reserved for cases with clinical features suggesting PCOS or persistent anovulation beyond 3 years post-menarche 2, 1
• Pelvic ultrasound (transabdominal preferred if not sexually active) is indicated only when hormonal tests suggest ovarian pathology or clinical features raise concern about structural abnormalities—not as routine screening 1

Management Algorithm Based on Findings

If No Pathology Identified (Physiologic Irregularity)

• Reassurance is the primary intervention for irregular cycles within the first 3 years post-menarche, as this typically represents normal hypothalamic-pituitary-ovarian axis maturation 1, 3
• Observation without treatment is appropriate unless bleeding is heavy, prolonged, or significantly impacts quality of life 4

If Treatment is Needed for Bothersome Bleeding

First-line approach:

• NSAIDs (mefenamic acid 500 mg three times daily or celecoxib 200 mg daily) for 5-7 days during bleeding episodes to reduce menstrual blood loss 4, 5

Second-line approach if NSAIDs fail:

• Low-dose combined oral contraceptives (30-35 μg ethinyl estradiol plus levonorgestrel or norgestimate) for 10-20 days provide cycle regulation and are safe throughout reproductive years 1, 5

If Specific Pathology Identified

• Thyroid dysfunction: Initiate levothyroxine at 1.6 mcg/kg/day, with menstrual cycles typically normalizing within 2-5 days of achieving adequate replacement 2
• Hyperprolactinemia: Refer to endocrinology for dopamine agonist therapy 2
• Functional hypothalamic amenorrhea: Address underlying causes first (stress reduction, nutritional optimization to >30 kcal/kg fat-free mass/day, reduction of excessive exercise) before considering hormonal therapy 1

Critical Pitfalls to Avoid

• Do not assume functional bleeding without excluding structural pathology if irregularity persists beyond 3 years post-menarche or if bleeding patterns are severe 1
• Avoid aspirin as it may increase blood loss in adolescents with baseline menstrual blood loss <60 mL 2
• Do not initiate extensive hormonal workup in the first 2 years post-menarche unless clinical features suggest specific pathology (severe androgen excess, galactorrhea, thyroid symptoms) 1, 3

Follow-Up and Referral Indications

• Reassess menstrual pattern within 1-2 cycles if symptomatic treatment was initiated 2
• Refer to endocrinology and/or gynecology when hormonal workup reveals complex abnormalities, bleeding persists despite two treatment attempts, or if infertility becomes a concern 2
• Monitor TSH every 6-12 months once stable on thyroid replacement if hypothyroidism was identified 2

The key distinction in adolescents is recognizing that irregular cycles are developmentally normal for 2-3 years post-menarche, with normal adolescent cycle length ranging 21-45 days compared to the adult range of 21-35 days 1. This wider physiologic variation means most 14-year-olds require reassurance rather than intervention, unless specific pathology is identified or quality of life is significantly impaired 4, 1.