What is the appropriate management for a 17-year-old female with microscopic hematuria, low ferritin (iron deficiency) levels, and no anemia?

Management of 17-Year-Old Female with Microscopic Hematuria and Low Ferritin Without Anemia

This patient requires both iron supplementation to replenish depleted stores AND urologic evaluation to exclude urinary tract pathology as the source of iron loss.

Immediate Iron Management

Start oral iron supplementation immediately despite the absence of anemia, as low ferritin indicates depleted iron stores that require repletion. 1

Iron Supplementation Protocol

• Prescribe ferrous sulfate 200 mg three times daily (or ferrous gluconate/fumarate as alternatives if not tolerated) 1
• For adolescent females, a single 60 mg elemental iron tablet daily is an acceptable alternative dosing strategy 1
• Administer iron between meals to optimize absorption 1
• Consider adding ascorbic acid (vitamin C) to enhance iron absorption, particularly if response is suboptimal 1
• Continue iron therapy for 3 months after ferritin normalizes to fully replenish body stores 1

Monitoring Response

• Recheck hemoglobin and ferritin in 8-10 weeks 2
• For adolescent females, a ferritin cut-off of 20 μg/L is appropriate for those aged 12-15 years, and 30 μg/L for those >15 years 2
• If ferritin remains low after initial treatment course, institute intermittent oral supplementation with monitoring every 6-12 months 2

Critical Urologic Evaluation

The presence of microscopic hematuria in the setting of iron deficiency mandates investigation for urinary tract pathology, as urinary tract tumors can rarely present with iron deficiency. 1

Hematuria Workup

• Confirm persistent microscopic hematuria with repeat urinalysis 3, 4
• Obtain detailed menstrual history, as menorrhagia is the most common cause of iron deficiency in this age group 1
• If hematuria persists on repeat testing, proceed with:
  • Renal ultrasonography to evaluate upper urinary tract 3
  • Consider cystourethroscopy if imaging is unrevealing and hematuria persists 3
  • Intravenous pyelography or retrograde pyelography may be required depending on initial findings 3

Rule Out Masked or Functional Iron Deficiency

Even with "normal" hemoglobin, this patient may have early iron-deficient erythropoiesis:

• Check transferrin saturation (TSAT)—a level <20% indicates functional iron deficiency even when hemoglobin appears normal 5
• Measure mean cell volume (MCV) and mean cell hemoglobin (MCH), as MCH decreases in both absolute and functional iron deficiency 5
• If inflammatory conditions are suspected, check C-reactive protein, as ferritin is an acute phase reactant and can mask true iron deficiency 5, 2

Exclude Alternative Causes

Menstrual Assessment

• Quantify menstrual blood loss using pictorial blood loss assessment charts (sensitivity and specificity ~80% for menorrhagia) 1
• Menstrual loss, especially menorrhagia, is responsible for iron deficiency in 5-10% of menstruating women 1

Dietary Evaluation

• Assess dietary iron intake, particularly if vegetarian/vegan diet, eating disorder, or underweight 2
• Counsel on incorporating heme and non-heme iron sources, enhancers of absorption (vitamin C), and avoiding inhibitors (tea, calcium) 2

Other Considerations

• Review medications, particularly NSAIDs which can cause occult GI blood loss 1
• In patients of Mediterranean, African, or Southeast Asian ancestry, consider hemoglobin electrophoresis to exclude thalassemia minor if MCV is disproportionately low 1, 5

Common Pitfalls to Avoid

• Do not dismiss low ferritin simply because hemoglobin is normal—iron stores are depleted and require repletion to prevent progression to anemia 1, 2
• Do not ignore microscopic hematuria in the setting of iron deficiency—urinary tract pathology must be excluded 1
• Avoid relying solely on serum iron levels, as they have significant diurnal variation and are less reliable than ferritin and TSAT 5
• Do not assume menstruation alone explains the findings without confirming persistent hematuria is not present 1, 3

Follow-Up Strategy

• Monitor hemoglobin and ferritin every 3 months for the first year, then annually 1
• Additional oral iron should be given if hemoglobin or MCV falls below normal 1
• Further investigation is only necessary if hemoglobin and iron indices cannot be maintained with supplementation 1
• If iron deficiency recurs despite adequate supplementation and correction of menstrual losses, intensify search for occult blood loss 1