What is the appropriate management for a patient with iron deficiency anemia, as indicated by low total iron, low percent saturation, and low ferritin levels, along with other specific laboratory values?

Management of Iron Deficiency Anemia

Start oral iron supplementation immediately with ferrous sulfate 325 mg daily (containing 65 mg elemental iron), taken on an empty stomach with 500 mg vitamin C, and simultaneously investigate the underlying cause of blood loss. 1, 2, 3

Confirm the Diagnosis

Your laboratory values definitively establish iron deficiency anemia:

• Ferritin 13 ng/mL (severely depleted iron stores; diagnostic threshold <45 ng/mL) 1
• Transferrin saturation 13% (absolute iron deficiency; normal >20%) 1, 4
• Total iron 45 μg/dL (low) 1
• MCH 25.4 pg and MCHC 30.1 g/dL (hypochromic microcytic anemia) 1
• RDW 16.3% (elevated, consistent with iron deficiency) 1
• Platelet count 479 (reactive thrombocytosis from chronic blood loss) 1

The combination of ferritin <15 ng/mL with transferrin saturation <20% has 99% specificity for absolute iron deficiency. 1

Immediate Treatment: Oral Iron Supplementation

First-line therapy:

• Ferrous sulfate 325 mg once daily (provides 65 mg elemental iron, which is 362% of the recommended daily intake) 3
• Take on an empty stomach (1 hour before or 2 hours after meals) for optimal absorption 2, 4
• Co-administer with 500 mg vitamin C to enhance absorption 2
• Avoid tea, coffee, calcium supplements, and high-fiber foods within 2 hours of dosing 2

Alternative dosing if gastrointestinal side effects occur:

• Switch to every-other-day dosing (ferrous sulfate 325 mg on alternate days), which improves absorption and reduces side effects 5, 6
• If intolerable, consider 100 mg elemental iron daily 5

Duration: Continue for at least 3-6 months to replenish iron stores (target ferritin >100 ng/mL). 1

Mandatory Investigation for Blood Loss

You must investigate the source of iron deficiency in parallel with treatment:

Non-invasive Testing First:

• Screen for celiac disease with tissue transglutaminase IgA antibody (common cause of malabsorption) 1
• Test for Helicobacter pylori (non-invasive breath or stool antigen test) 1

Endoscopic Evaluation:

The 2020 Gastroenterology guidelines provide clear direction based on patient demographics:

For men and postmenopausal women:

• Bidirectional endoscopy is strongly recommended (upper endoscopy AND colonoscopy) to exclude gastrointestinal malignancy 1
• This is a strong recommendation with moderate quality evidence 1
• Proceed even if H. pylori or celiac testing is positive, unless advanced gastric cancer or severe celiac disease is found 1

For premenopausal women:

• Investigation is a conditional recommendation 1
• If the patient is younger with obvious menorrhagia and no gastrointestinal symptoms, you may reasonably start with empiric iron supplementation alone 1
• However, maintain a low threshold for endoscopy if there are GI symptoms, family history of colorectal cancer, age >50 years, or failure to respond to iron therapy 1

Do NOT perform:

• Fecal occult blood testing (no benefit in iron deficiency anemia workup) 1

Monitor Treatment Response

Reassess in 2-4 weeks:

• Check hemoglobin (should increase by 1-2 g/dL after 3-4 weeks of therapy) 6
• Assess symptom improvement (fatigue, exercise tolerance) 4

Repeat iron studies at 8-10 weeks:

• Ferritin, transferrin saturation, and complete blood count 2
• Goal: ferritin >100 ng/mL to confirm adequate iron store repletion 1

When to Switch to Intravenous Iron

Consider IV iron if: 1, 7, 4

• Intolerance to oral iron despite alternate-day dosing
• No response after 4-6 weeks of adequate oral therapy
• Ongoing blood loss exceeding absorption capacity (e.g., angiodysplasia)
• Malabsorption (celiac disease, inflammatory bowel disease, post-bariatric surgery)
• Severe anemia with symptoms requiring rapid correction
• Chronic inflammatory conditions (heart failure, chronic kidney disease, inflammatory bowel disease)

Critical Pitfalls to Avoid

• Do not delay investigation while treating with iron—gastrointestinal malignancy must be excluded in men and postmenopausal women 1
• Do not rely on stool guaiac testing for investigation (it is unreliable in this context) 1
• Do not assume menstruation is the cause in premenopausal women without first excluding celiac disease and H. pylori 1
• Do not stop iron supplementation when hemoglobin normalizes—continue until ferritin >100 ng/mL to replenish stores 1
• Do not use blood transfusion unless the patient has cardiovascular instability 1

Address Underlying Cause

Once identified through investigation:

• Treat H. pylori if present (can cause iron deficiency even without ulcers) 1
• Manage celiac disease with gluten-free diet 1
• Treat gastrointestinal lesions (polyps, angiodysplasia, malignancy) as indicated 1
• Manage menorrhagia in premenopausal women (hormonal therapy, IUD, gynecology referral) 2, 4