What is the management for a patient with iron deficiency anemia, low iron, low iron saturation, and low ferritin, but a normal CBC?

Management of Non-Anemic Iron Deficiency

This patient has non-anemic iron deficiency (NAID) and should be treated with oral iron supplementation while investigating for underlying causes, particularly gastrointestinal pathology if the patient is male, postmenopausal, or has concerning symptoms. 1

Understanding the Clinical Picture

Your patient's laboratory values confirm iron deficiency despite a normal CBC:

• Ferritin 11 ng/mL is highly specific for depleted iron stores (diagnostic threshold <15 ng/mL, with <30 ng/mL indicating low body iron stores) 1
• Iron saturation of 8% is markedly reduced (normal >20-30%) 1, 2
• Low serum iron (32) with elevated TIBC reflects the body's attempt to capture more iron when stores are depleted 3

This represents the early phase of iron deficiency where body iron stores are depleted but hemoglobin remains within normal range 1. The patient will likely progress to iron deficiency anemia if left untreated.

Immediate Treatment Approach

Oral Iron Supplementation

Start ferrous sulfate 325 mg daily (containing 65 mg elemental iron) as first-line therapy 3, 4, 2:

• Consider alternate-day dosing if gastrointestinal side effects develop (constipation, nausea, diarrhea), which may actually improve iron absorption 3, 5
• Counsel patients to take iron with vitamin C to enhance absorption and avoid tea/coffee around dosing times 3
• Recheck hemoglobin and iron studies after 8-10 weeks to assess response; expect 1-2 g/dL hemoglobin increase if effective 3, 5

Investigation for Underlying Cause

The decision to investigate depends critically on patient demographics and risk factors:

Men and Postmenopausal Women

GI investigation should be strongly considered even without anemia, as the overall prevalence of significant GI pathology is lower in NAID than in frank anemia, but serious conditions including malignancy can still present this way 1:

• Bidirectional endoscopy (upper and lower GI) is recommended if the patient is male or postmenopausal 1, 5
• Obtain celiac serology (tissue transglutaminase antibody) at presentation, as 2-5% of patients with iron deficiency have celiac disease 1, 5
• Test for Helicobacter pylori, as this is a common cause of iron deficiency 5, 6
• Consider dual pathology (bleeding sources in both upper and lower GI tracts), which occurs in 1-10% of patients, especially in older individuals 1

Premenopausal Women

GI investigation generally is not warranted in the absence of other concerning features, since menorrhagia is the most common cause 1:

• Over half of young women with menorrhagia have reduced iron stores but only 25% are actually anemic 1
• However, investigate if: patient has GI symptoms, family history of GI malignancy, age >50 years, or fails to respond to iron supplementation 1

Key History Elements

• Document NSAID/aspirin use and stop if possible, as these are common causes of occult GI bleeding 1
• Assess dietary iron intake, though borderline deficient diets alone should not preclude GI investigation in high-risk patients 1
• Screen for symptoms of malabsorption (diarrhea, weight loss) suggesting celiac disease or inflammatory bowel disease 2, 6

When to Consider Intravenous Iron

IV iron is indicated if the patient 3, 2, 5:

• Fails oral iron therapy after 8-10 weeks
• Cannot tolerate oral iron despite alternate-day dosing
• Has documented malabsorption (celiac disease, post-bariatric surgery)
• Has ongoing significant blood loss
• Has chronic inflammatory conditions (CKD, heart failure, IBD, cancer)

Critical Monitoring Considerations

• Do not recheck ferritin immediately after starting treatment; it takes 8-10 weeks to accurately reflect response 3
• Target ferritin levels above 30 ng/mL but below 800 ng/mL to avoid iron overload 3
• Keep transferrin saturation below 50% to prevent iron toxicity 3
• If no response to oral iron after 8-10 weeks, consider malabsorption, ongoing blood loss, or non-compliance as causes 3, 5

Common Pitfalls to Avoid

• Do not assume dietary deficiency alone explains iron deficiency in men or postmenopausal women—always investigate for GI pathology 1
• Do not delay investigation in patients with "mild" iron deficiency—there is no evidence that mild deficiency is less indicative of serious disease than severe deficiency 1
• Do not overlook celiac disease—it accounts for 2-5% of iron deficiency cases and is easily missed without serologic testing 1, 5
• Do not continue iron supplementation indefinitely without monitoring—iron overload is potentially harmful 3