How should an adult patient with iron deficiency anemia, indicated by an iron level of 20 and iron saturation of 7, be treated?

Iron Deficiency Anemia with Iron 20 and Saturation 7%

You have severe absolute iron deficiency anemia requiring immediate oral iron replacement AND urgent gastrointestinal investigation to exclude malignancy and other serious pathology. 1, 2

Immediate Treatment

Start ferrous sulfate 325 mg (65 mg elemental iron) once daily immediately. 2, 3 This is first-line therapy for iron deficiency anemia. 1, 2

• If gastrointestinal side effects occur, reduce to every-other-day dosing rather than stopping completely—this maintains efficacy while improving tolerability. 2, 4
• Expect hemoglobin to rise ≥10 g/L within 2 weeks if this is true iron deficiency, which confirms the diagnosis even with equivocal labs. 1, 2
• Continue iron therapy for 3 months after hemoglobin normalizes to replenish iron stores. 1

Mandatory Investigation for Underlying Cause

Your iron saturation of 7% (normal >20%) with these values indicates absolute iron deficiency that demands urgent investigation. 1, 2 Approximately one-third of adults with unexplained iron deficiency anemia have underlying gastrointestinal pathology, including malignancy. 1

Required Testing:

• Bidirectional endoscopy (upper endoscopy AND colonoscopy) to exclude gastric cancer, colorectal cancer, celiac disease, inflammatory bowel disease, and angiodysplasia. 1, 2
• Celiac disease screening via serology or small bowel biopsy at gastroscopy—found in 3-5% of iron deficiency anemia cases. 1
• Urinalysis to exclude urinary tract bleeding. 1

Who Needs Investigation:

• All men and postmenopausal women with new iron deficiency anemia require urgent gastrointestinal evaluation. 1, 2
• Premenopausal women if age >40 years or if heavy menstrual bleeding doesn't fully explain the severity. 2

Critical pitfall: Do not accept findings like esophagitis, gastric erosions, or peptic ulcer as the sole cause without also examining the lower gastrointestinal tract—dual pathology occurs in 10-15% of cases. 1

Monitoring Response

• Recheck hemoglobin in 2 weeks. A rise of ≥10 g/L confirms iron deficiency and adequate response. 1, 2
• Monitor every 3 months for one year after correction, then again at 2 years. 1, 2
• If hemoglobin doesn't rise or iron deficiency recurs despite treatment, further investigation is needed. 1

When to Consider Intravenous Iron

Switch to intravenous iron if: 2, 5, 6

• Oral iron is not tolerated despite every-other-day dosing
• No hemoglobin response after 4 weeks of oral therapy
• Ongoing blood loss exceeds intestinal absorption capacity
• Malabsorption is identified (celiac disease, inflammatory bowel disease, post-bariatric surgery)
• Chronic inflammatory conditions are present (chronic kidney disease, heart failure, inflammatory bowel disease)

Intravenous iron has superior efficacy compared to oral iron, particularly in patients with chronic inflammatory conditions. 1, 6

Special Considerations

Your transferrin saturation of 7% with elevated total iron binding capacity indicates absolute iron deficiency, not functional iron deficiency or anemia of chronic disease. 1, 2 This pattern demands investigation regardless of hemoglobin level. 2

If chronic kidney disease (GFR <60 mL/min/1.73m²) or chronic heart failure is present, coordinate with nephrology or cardiology teams as these conditions require modified diagnostic thresholds and often necessitate intravenous iron therapy. 1