In a 13‑year‑old female adolescent weighing approximately 129 lb (58 kg), should iron supplementation be initiated, and if so, what is the appropriate oral iron preparation, dosage, and duration?

Iron Supplementation for a 13-Year-Old Female

Iron supplementation should not be initiated routinely without first screening for anemia and confirming iron deficiency, but if anemia is documented, treat with 60-120 mg of elemental iron daily for at least 3 months total. 1, 2

Screening First, Not Routine Supplementation

• Most adolescent girls do not require iron supplements without documented deficiency. 3
• Screen this patient for anemia using hemoglobin or hematocrit, as the CDC recommends screening adolescent girls every 5-10 years during routine health examinations, or annually if risk factors are present. 3, 1
• Risk factors warranting screening include: heavy menstrual bleeding, low dietary iron intake, restrictive diets, previous iron deficiency anemia, or special healthcare needs. 3, 1, 4
• Anemia in a 13-year-old female is defined as hemoglobin <12.0 g/dL or hematocrit <36%. 1

If Anemia is Confirmed: Diagnostic Approach

• Confirm a positive screening result with a repeat hemoglobin or hematocrit test. 3
• If the patient is not acutely ill, you can make a presumptive diagnosis of iron deficiency anemia and begin treatment empirically. 3, 1
• The diagnosis is confirmed retrospectively if hemoglobin increases by ≥1 g/dL (or hematocrit by ≥3%) after 4 weeks of iron therapy. 3, 1, 2

Treatment Protocol When Anemia is Present

Dosing:

• Prescribe 60-120 mg of elemental iron daily (the CDC guideline range for adolescent girls). 3, 2, 4
• Administer iron between meals or on an empty stomach to maximize absorption, though it can be taken with food if gastrointestinal side effects occur. 1, 2, 4
• Recommend vitamin C-rich foods or supplements with iron to enhance absorption. 2, 4

Dietary counseling:

• Emphasize iron-rich foods, particularly heme iron from meat, poultry, and fish (bioavailability 15-35%), which is superior to plant-based non-heme iron (<10% bioavailability). 3, 2
• Pair plant-based iron sources with vitamin C to enhance absorption. 2

Monitoring and Duration

• Recheck hemoglobin after 4 weeks of treatment. 3, 1, 2, 4
• If hemoglobin increases by ≥1 g/dL, the diagnosis is confirmed—continue iron for an additional 2-3 months to replenish iron stores. 3, 1, 2, 4
• Total treatment duration is typically 3 months minimum for confirmed iron deficiency anemia. 2
• Reassess hemoglobin approximately 6 months after completing treatment. 1, 4

If Treatment Fails After 4 Weeks

• If anemia does not respond despite compliance and absence of acute illness, obtain additional laboratory tests: mean corpuscular volume (MCV), red cell distribution width (RDW), and serum ferritin. 3, 1, 2
• Serum ferritin <15 μg/L confirms iron deficiency; >15 μg/L suggests another cause. 3, 1
• In patients of African, Mediterranean, or Southeast Asian ancestry, consider thalassemia minor or sickle cell trait if anemia is unresponsive to iron. 3, 2

Critical Pitfalls to Avoid

• Do not supplement iron without screening for anemia first—routine supplementation is not recommended for adolescent girls without documented deficiency. 3
• Do not stop iron therapy as soon as hemoglobin normalizes—stores must be replenished over 2-3 additional months. 3, 2, 4
• Do not assume all microcytic anemia is iron deficiency—thalassemia trait should be considered in at-risk populations. 2
• Gastrointestinal side effects (dyspepsia, constipation) are common with oral iron and may limit compliance; consider taking with food or trying different formulations (ferrous gluconate, ferrous fumarate, or liquid preparations) if intolerance occurs. 4, 5

Physiologic Context for Adolescent Females

• Female adolescents have higher iron requirements (0.35 mg/kg) than males (0.2 mg/kg) due to menstrual blood loss. 3
• During puberty, rapid growth increases blood volume substantially, requiring approximately 1000 mg of iron dedicated to erythropoiesis alone. 3
• Hepcidin levels decrease during adolescence in response to sex hormones, which physiologically adapts to increased iron demands from growth and menstruation. 3