Management of Fatigue and Heavy Menstrual Bleeding in a 17-Year-Old
Your next step is to measure ferritin levels immediately, as iron deficiency without anemia is present in approximately 50% of adolescents with heavy menstrual bleeding and is the most likely cause of her fatigue, even with a normal CBC. 1, 2
Why the Normal CBC is Insufficient
- Hemoglobin and CBC alone miss over half of iron deficiency cases in young women with heavy menstrual bleeding, with a sensitivity of only 41-46% for detecting ferritin <20 ng/mL 2
- Among adolescents with heavy menstrual bleeding who have iron deficiency (ferritin <20 ng/mL), only 41% are anemic and only 46% show microcytosis on CBC 2
- Iron deficiency is present in 87.5% of adolescents with heavy menstrual bleeding, with ferritin ≤40 ng/mL, and 29% have severe depletion with ferritin ≤15 ng/mL 1
Complete Your Pending Workup
While awaiting TSH and CMP results, recognize that:
- TSH testing is essential to exclude thyroid dysfunction as a reversible cause of both fatigue and menstrual irregularities 3, 4, 5
- The CMP will help identify any metabolic abnormalities, though these are less likely contributors in this clinical scenario 3
- Fatigue severity scores are significantly elevated in young women with heavy menstrual bleeding compared to healthy controls, independent of anemia status 1
Immediate Laboratory Additions
Order ferritin now rather than waiting for the gynecology appointment, as this will:
- Identify iron deficiency that the CBC missed 2
- Guide immediate iron supplementation to improve fatigue symptoms 1
- Provide the gynecologist with complete information for treatment planning 6
Common Pitfall to Avoid
Never assume a normal hemoglobin rules out clinically significant iron deficiency in adolescents with heavy menstrual bleeding. The ferritin level is the critical test, as iron stores become depleted long before anemia develops, and this depletion directly causes fatigue 1, 2
Coordinate with Gynecology Referral
The gynecology referral is appropriate for addressing the heavy menstrual bleeding itself through:
- Hormonal management options including levonorgestrel-releasing intrauterine systems or combined hormonal contraceptives as first-line treatments 6
- Tranexamic acid (antifibrinolytic therapy) as an alternative or adjunct, which reduces menstrual blood loss by 40-50% 7, 6
- Evaluation for underlying bleeding disorders, which are present in up to 20% of adolescents with heavy menstrual bleeding 6
Treatment Sequence
- Start iron supplementation immediately if ferritin is <40 ng/mL, as this threshold indicates depleted iron stores even without anemia 1
- Address the heavy menstrual bleeding through gynecologic management to prevent recurrent iron deficiency 6
- Reassess fatigue symptoms after 4-6 weeks of iron therapy, as improvement confirms iron deficiency as the primary cause 1