Should iron supplementation be started in a 15-year-old patient with fatigue, normal hemoglobin, low iron and iron saturation levels, and low-normal ferritin?

Iron Supplementation Should Be Started in This 15-Year-Old

Yes, iron supplementation should be initiated immediately in this adolescent with fatigue, low iron, low iron saturation, and low-normal ferritin, even with normal hemoglobin. This represents non-anemic iron deficiency, which requires treatment to prevent progression to iron deficiency anemia and to address current symptoms.

Diagnostic Confirmation

For adolescents aged 12-15 years, a ferritin threshold of 20 μg/L is recommended for diagnosing iron deficiency 1. However, for adolescents aged >15 years, a ferritin cut-off of 30 μg/L is more appropriate 2, 3, 1. Your patient's "low-normal" ferritin combined with low iron and low iron saturation confirms depleted iron stores 3.

• Low transferrin saturation (<20%) further supports the diagnosis of absolute iron deficiency 4
• The presence of fatigue is a clinically significant symptom directly attributable to iron deficiency, even without anemia 5, 2, 4
• Iron deficiency without anemia can cause fatigue, decreased physical and cognitive performance, headaches, and sleep disturbances 2

Treatment Recommendations

Start oral iron supplementation as first-line therapy:

• Ferrous sulfate 325 mg once daily (containing approximately 65 mg elemental iron) or equivalent ferrous gluconate/fumarate 2, 4
• Alternatively, 100-200 mg elemental iron per day in divided doses is acceptable 5
• Add vitamin C (ascorbic acid) to enhance iron absorption 2, 3
• Administer in the morning on an empty stomach for optimal absorption 6

Key Administration Points

• Once-daily dosing is preferred over multiple daily doses, as it maximizes absorption and reduces gastrointestinal side effects 6
• Avoid foods and drinks that inhibit iron absorption (tea, coffee, calcium-rich foods) when taking iron 6
• If gastrointestinal side effects occur, consider alternate-day dosing, which may improve absorption and reduce adverse effects 5, 2

Duration and Monitoring

Continue treatment for at least 3 months after ferritin normalization to fully replenish iron stores 2, 3:

• Repeat hemoglobin and ferritin levels after 8-10 weeks of treatment 5, 1
• Target ferritin >100 μg/L to prevent recurrence 2
• For adolescents with recurrent low ferritin, long-term follow-up every 3-6 months is recommended 1

When to Consider Intravenous Iron

Intravenous iron is reserved for specific situations 2, 3, 6:

• Intolerance to at least two oral iron preparations
• Persistent iron deficiency despite adequate oral therapy
• Severe symptomatic anemia requiring rapid correction
• Chronic inflammatory conditions affecting absorption

Critical Pitfalls to Avoid

• Do not delay treatment while investigating the underlying cause - start supplementation immediately 2, 3
• Do not use preparations with excessive elemental iron content (>50 mg), as this increases side effects without improving efficacy 1
• Avoid long-term supplementation once ferritin normalizes, as excessive iron is potentially harmful 3, 1
• Do not recheck ferritin too early after starting treatment (wait 8-10 weeks) 5, 1

Adolescent-Specific Considerations

Adolescents are at particularly high risk for iron deficiency due to 6, 4:

• Rapid growth and increased iron requirements
• Menstrual blood loss in females
• Dietary habits (vegetarian/vegan diets, disordered eating)
• Athletic activity increasing iron demands

For this 15-year-old, investigate potential causes including menstrual patterns (if female), dietary intake, athletic participation, and gastrointestinal blood loss, but begin treatment concurrently 4.