Clinical Resources for Clinicians · For clinicians
Iron Deficiency Without Anemia in Adolescents With Heavy Menstrual Bleeding
Adolescents with heavy menstrual bleeding often have depleted iron stores while hemoglobin is still normal, and a CBC alone will miss it. ACOG Committee Opinion 785 recommends checking serum ferritin as part of the HMB evaluation and notes that low iron stores without anemia are associated with fatigue and decreased cognition. The practical sequence: find the deficiency, treat it, reduce menstrual losses, and screen for an underlying bleeding disorder.
The pattern is familiar in practice. A 15-year-old comes in for a sports physical or a "tired all the time" visit, the hemoglobin is 12.4, everyone relaxes, and nobody orders a ferritin. Six months later she's anemic. This piece is about catching her the first time.
Why adolescents are at risk
Iron requirements climb steeply in adolescence. Growth, expanding red cell mass and the onset of menses all compete for iron, while intake in this age group is often low. Add HMB and stores can drain within months.
Three things make it easy to miss:
- Normalized heavy bleeding. Teens have no reference point, and a mother or sister may have the same pattern. "My periods are just like that" is a history, not a reassurance.
- Nonspecific symptoms. Fatigue, poor concentration, exercise intolerance, headaches, restless legs and pica (ice chewing in particular) get attributed to school, sleep or mood.
- Hemoglobin falls last. Ferritin drops well before anemia appears.
ACOG Committee Opinion 651 frames the menstrual cycle as a vital sign. Asking about flow, duration and impact at every adolescent visit is the simplest screen we have.
Eliciting HMB: questions that work
Vague questions ("Are your periods heavy?") get vague answers. Concrete ones work better:
- On your heaviest day, how often do you change pads or tampons? Do you ever soak through in an hour or two?
- Do you get up at night to change, or wear a pad and tampon together?
- Do you pass clots? Bigger than a quarter?
- How many days does your period last?
- Have you missed school, practice or activities because of your period?
- Have you leaked through clothes or onto sheets?
Pictorial blood loss charts help quantify bleeding, though they're imperfect. See the adolescent alone for part of the visit; answers often change when a parent steps out.
Testing
For an adolescent with HMB, per ACOG CO 785:
| Test | Purpose |
|---|---|
| CBC with platelets | Anemia, thrombocytopenia |
| Serum ferritin | Iron stores; the key test for non-anemic deficiency |
| Pregnancy test | As indicated |
| Thyroid function | If clinically indicated |
| Bleeding-disorder evaluation | If screen positive; coordinate with hematology |
Interpreting ferritin
| Ferritin | Interpretation in a well adolescent |
|---|---|
| < 15 µg/L | Iron deficiency by the older WHO threshold for individuals aged 5 and older |
| ≤ 30 µg/L | Iron deficiency under the 2026 ASH diagnostic guideline for menstruating individuals |
| 30–50 µg/L | ASH 2026 notes a cutoff of up to 50 may be appropriate with symptoms or ongoing risk factors such as continuing HMB |
| > 50 µg/L | Iron deficiency less likely, unless inflammation is raising ferritin |
WHO's 15 µg/L cutoff is specific but insensitive. The 2026 ASH guideline on diagnosing iron deficiency raised the threshold for menstruating individuals to 30 ng/mL (µg/L), and allows up to 50 ng/mL for patients with symptoms or ongoing risk factors, which describes many adolescents with HMB. With inflammation, ASH recommends ferritin and TSAT together. Ferritin is an acute-phase reactant, so draw it when the patient is well, not during a viral illness. More in interpreting iron studies.
A practical point: many lab reports still flag ferritin as "normal" down to the low teens. A ferritin of 18 with a green check mark next to it is one of the most common ways this diagnosis gets missed.
Treating the deficiency
Oral iron
- First-line for most adolescents
- A moderate dose once daily or on alternate days improves tolerability, and alternate-day dosing may improve absorption
- Counsel to take it away from dairy, calcium, tea and coffee, and with vitamin C
- Address constipation and nausea up front. Tolerability drives adherence, and adherence in teenagers is the whole game.
- Recheck ferritin after about 2 to 3 months and continue until stores are replete
When to consider IV iron
- Intolerance, or no response despite confirmed adherence
- Severe deficiency with ongoing heavy losses that oral iron can't keep up with
- Malabsorption, such as celiac disease or IBD
- Anemia needing rapid correction, for example before surgery
IV iron is used in adolescents with weight-appropriate dosing. Refer to a setting experienced with younger patients, and confirm the infusion site's age policy before you send the referral.
Reducing menstrual losses
Iron alone fails if bleeding continues unchanged. Options:
- Hormonal therapy: combined hormonal contraception, progestin-only methods, or an LNG-IUD, which is appropriate and effective in adolescents
- Tranexamic acid during menses, a nonhormonal option
- NSAIDs during menses, which reduce flow modestly. Avoid them if a bleeding disorder is suspected and not yet evaluated.
Choose based on the patient's preferences, contraceptive needs and any bleeding-disorder diagnosis. In New York, minors can consent to their own contraception, which matters when a teen wants hormonal treatment but isn't ready to involve a parent.
Screening for a bleeding disorder
ACOG CO 785 notes that a bleeding disorder is second only to anovulation as a cause of HMB in adolescents, and HMB from menarche is particularly suggestive of von Willebrand disease. Use a structured history:
- HMB since menarche
- Bleeding with dental work, surgery or minor wounds
- Frequent nosebleeds or easy bruising
- Family history of bleeding or a known bleeding disorder
A positive screen calls for VWF antigen, VWF activity and factor VIII, coordinated with hematology. Draw labs before starting hormonal therapy where possible, because estrogen raises VWF and can mask mild VWD. Don't delay treatment for an adolescent who is bleeding heavily to get the timing perfect. See the HMB bleeding-disorder workup.
Acute heavy bleeding
An adolescent with acute heavy bleeding and symptomatic anemia needs urgent assessment and may need admission, high-dose hormonal therapy, tranexamic acid, transfusion and hematology input. Draw bleeding-disorder labs before blood products or estrogen where feasible.
Higher-risk subgroups
Adolescent athletes, especially endurance athletes, have additional iron losses. Teens on vegetarian or vegan diets, or restricting intake for weight or sport, are also at risk. In these groups, ferritin is worth checking even when bleeding is only moderately heavy. Stay alert for disordered eating, which can present with menstrual changes and nutritional deficiencies.
Follow-up
- Recheck CBC and ferritin until stores are replete
- Reassess bleeding at every visit
- Re-screen ferritin periodically while HMB continues
- Document the iron and bleeding history clearly for the transition from pediatric to adult care. Our hematology referral checklist covers when to bring in a hematologist.
Talking with teens and families
Teens are often embarrassed to describe bleeding, and parents may see heavy periods as normal because theirs were the same. Concrete product questions, time alone with the patient, and a clear statement that heavy bleeding is a treatable medical problem go a long way. If a bleeding disorder is diagnosed, explain that it can run in families; the mother with "the same periods" may benefit from evaluation too.
School nurses, school-based health centers and sports medicine clinicians are useful partners. They often hear about fatigue or exercise intolerance first and can nudge teens back for follow-up labs. Many adolescents in New York are covered by Medicaid or Child Health Plus; confirm coverage for ferritin rechecks and any IV iron referral up front so a prior authorization doesn't stall treatment.
Referral partnership in New York
Adolescents with refractory iron deficiency, a positive bleeding screen or borderline VWF results benefit from a smooth handoff to hematology. Premier Hematology & Oncology, which sponsors our professional resources, offers referral pathways, fast-track IV iron scheduling and co-management across the New York area; confirm age eligibility when you set up the pathway. Details are on our hematology partners page.
Frequently asked questions
Should adolescents with heavy periods have ferritin checked?
Yes. ACOG Committee Opinion 785 recommends assessing for anemia from blood loss, including serum ferritin, in adolescents who present with heavy menstrual bleeding.
Does iron deficiency without anemia cause symptoms?
It can. ACOG notes that low iron stores in adolescents with heavy menstrual bleeding are associated with fatigue and decreased cognition, even when hemoglobin is normal.
What ferritin level should be treated in a teenager?
The 2026 ASH diagnostic guideline uses ferritin of 30 ng/mL or lower to define iron deficiency in menstruating individuals, replacing older 15 ng/mL cutoffs. Confirm age-specific application with pediatric hematology, and interpret results in clinical context.
Do teens with heavy periods need a bleeding disorder workup?
Those who screen positive do. HMB since menarche is particularly suggestive of a bleeding disorder such as von Willebrand disease, and ACOG recommends coordinating testing with hematology.
Sources
- ASH — 2026 Guidelines for Diagnosis of Iron Deficiency (Blood Advances)
- ACOG — Screening and Management of Bleeding Disorders in Adolescents With Heavy Menstrual Bleeding (Committee Opinion No. 785)
- ACOG — Menstruation in Girls and Adolescents: Using the Menstrual Cycle as a Vital Sign (Committee Opinion No. 651)
- WHO — Guideline on use of ferritin concentrations to assess iron status in individuals and populations (2020)
- WHO — Guideline on haemoglobin cutoffs to define anaemia in individuals and populations (2024)
- ASH ISTH NHF WFH — 2021 guidelines on the diagnosis of von Willebrand disease
This article is for general education and is not medical advice. It does not replace an evaluation by a licensed clinician who knows your history. If you think you have a medical emergency, call 911.