What is the best course of treatment for a patient with low iron saturation, abnormal red blood cell indices, and normal ferritin levels, indicating potential iron deficiency anemia?

Management of Iron Deficiency Anemia

The patient's laboratory values indicate iron deficiency anemia requiring oral iron supplementation with ferrous sulfate 325 mg daily (providing 65 mg of elemental iron) for 3-6 months to replenish iron stores. 1, 2

Diagnosis Analysis

The patient's laboratory results show:

• Low iron saturation (9%, reference range 15-55%)
• Low-normal ferritin (16 ng/mL, reference range 15-150 ng/mL)
• Low MCH (24.6 pg, reference range 26.6-33.0 pg)
• Low MCHC (30.4 g/dL, reference range 31.5-35.7 g/dL)
• Elevated RDW (19.7%, reference range 11.7-15.4%)
• Normal hemoglobin (11.9 g/dL)
• Normal MCV (81 fL) 1

These findings are consistent with early iron deficiency anemia characterized by:

• Hypochromia (low MCH and MCHC)
• Increased red cell distribution width (RDW)
• Low iron saturation
• Low-normal ferritin 1

Treatment Approach

First-line Treatment

• Oral iron therapy: Ferrous sulfate 325 mg daily (providing 65 mg of elemental iron) 2, 3
• Alternative dosing: Ferrous sulfate on alternate days may improve tolerance and absorption 3
• Duration: 3-6 months to fully replenish iron stores 4, 3

Administration Tips

• Take on an empty stomach if tolerated (1 hour before or 2 hours after meals) 4
• Co-administer with vitamin C (orange juice or vitamin C supplement) to enhance absorption 1
• Avoid taking with tea, coffee, calcium supplements, or antacids which impair absorption 1

Monitoring Response

• Expect hemoglobin rise of ≥10 g/L within 2 weeks if responding appropriately 1
• Recheck complete blood count after 4-8 weeks of therapy 4
• Monitor iron studies after 3 months to assess replenishment of iron stores 1

Etiologic Investigation

Since the patient has confirmed iron deficiency, further investigation for underlying causes is warranted:

Required Investigations

• Detailed dietary history to assess iron intake 1
• Menstrual history if female patient (heavy menstrual bleeding is a common cause) 3
• Screening for gastrointestinal blood loss:
  • Fecal occult blood testing 1
  • Upper GI endoscopy with duodenal biopsies (to rule out celiac disease) 1
  • Colonoscopy (especially important in men and postmenopausal women) 1

Common Etiologies to Consider

• Inadequate dietary intake 3
• Blood loss (menstrual, gastrointestinal) 3
• Malabsorption (celiac disease, post-gastrectomy, atrophic gastritis) 1, 3
• NSAID use causing gastrointestinal bleeding 1
• Chronic inflammatory conditions (inflammatory bowel disease, chronic kidney disease) 3

Special Considerations

• Even though ferritin is within normal range (16 ng/mL), values <30 μg/L generally indicate low iron stores 1, 5
• The combination of low iron saturation, low MCH, and elevated RDW strongly supports iron deficiency despite normal hemoglobin 1
• Current ferritin reference ranges may underdiagnose iron deficiency, especially in women 5
• Consider parenteral iron if oral iron is not tolerated or absorbed, or if there is ongoing blood loss 4, 3

Common Pitfalls to Avoid

• Don't assume normal ferritin excludes iron deficiency when it's in the low-normal range (15-30 μg/L) 1, 5
• Don't overlook the need for GI investigation despite mild anemia or normal hemoglobin 1
• Don't attribute iron deficiency solely to dietary factors without investigating potential blood loss 1
• Don't stop iron supplementation too early (continue for 3-6 months to replenish stores) 4, 3
• Don't forget to counsel patients about common side effects of oral iron (constipation, nausea, black stools) 4