What is the best course of treatment for a patient with iron deficiency anemia, low ferritin, and low MCHC?

Iron Deficiency Treatment in a Patient with Low Ferritin and Bruising

This patient has clear iron deficiency anemia (IDA) requiring oral iron supplementation as first-line therapy, with ferrous sulfate 325 mg daily or on alternate days being the standard treatment approach. 1, 2

Interpretation of Laboratory Findings

Your patient's laboratory pattern is diagnostic of iron deficiency:

• Low ferritin (7 ng/mL) - This is well below the diagnostic threshold of 30 ng/mL for iron deficiency in adults without inflammation 1, 2
• Low MCHC - Indicates hypochromic red blood cells, consistent with inadequate iron for hemoglobin synthesis 1
• High unsaturated iron binding capacity (UIBC) and elevated total iron binding capacity (TIBC) - These findings reflect the body's attempt to capture more iron when stores are depleted 1
• Low calculated iron saturation - Confirms insufficient iron availability for erythropoiesis 1

The normal comprehensive metabolic panel and absence of inflammatory markers (based on your description) means the ferritin accurately reflects true iron deficiency rather than being falsely elevated by inflammation 1, 3.

Treatment Recommendation

First-Line: Oral Iron Supplementation

Start ferrous sulfate 325 mg daily (containing 65 mg elemental iron), which can be taken on alternate days if gastrointestinal side effects develop. 1, 4, 2

• Oral iron is the appropriate first-line therapy for patients without malabsorption, intolerance, or ongoing significant blood loss 1, 2
• Alternate-day dosing (rather than daily) may improve iron absorption and reduce gastrointestinal side effects like constipation, diarrhea, and nausea 1
• Typical oral iron doses range from 100-200 mg elemental iron daily in divided doses, though recent evidence supports alternate-day dosing 1

Dietary Optimization

Counsel the patient to consume iron-rich foods, particularly red meat (heme iron), and co-ingest vitamin C with non-heme iron sources while avoiding tea and coffee around meal times. 1

• Heme iron from meat and seafood has substantially higher bioavailability than non-heme iron from plant sources 1
• Vitamin C enhances non-heme iron absorption 1
• Tea and coffee contain compounds that impair iron absorption and should be avoided around meals 1

Investigation of Underlying Cause

The bruising combined with iron deficiency mandates investigation for a bleeding source, particularly gastrointestinal bleeding. 1, 2

Key considerations include:

• Menstrual blood loss - In reproductive-age women, heavy or prolonged menstruation is the most common cause (38% have iron deficiency without anemia, 13% have iron-deficiency anemia) 2
• Gastrointestinal bleeding - NSAID use, peptic ulcer disease, gastritis, or malignancy must be excluded 1, 2
• Malabsorption - Celiac disease, atrophic gastritis, or prior bariatric surgery can impair iron absorption 2
• Dietary inadequacy - Particularly in vegetarians/vegans or those with eating disorders 5

The presence of bruising raises concern for a platelet disorder or coagulopathy, though you note the CBC shows only low MCHC. Ensure platelet count and coagulation studies are normal 1.

Monitoring Response to Treatment

Recheck hemoglobin after 8-10 weeks of oral iron therapy. 1, 5

• Expect a 1-2 g/dL increase in hemoglobin if treatment is effective 6
• If hemoglobin fails to rise appropriately, consider: malabsorption of oral iron, continued bleeding, or an unidentified lesion 6
• Do not recheck ferritin immediately after starting treatment, as it takes 8-10 weeks to accurately reflect response 1, 5

When to Consider Intravenous Iron

Intravenous iron is indicated if the patient fails oral iron therapy, has documented malabsorption, cannot tolerate oral iron, or has ongoing significant blood loss. 1, 2

Specific indications include:

• Oral iron intolerance or poor absorption (celiac disease, post-bariatric surgery) 2
• Chronic inflammatory conditions (though your patient appears to lack these) 1, 2
• Ongoing blood loss requiring rapid iron repletion 1
• Repeated failure of oral therapy 1, 5

The most commonly used IV iron formulations include ferric carboxymaltose, iron sucrose, and ferric gluconate, with modern formulations having very low rates of serious reactions (<1:250,000 administrations) 1.

Critical Safety Considerations

Do not supplement iron if ferritin levels normalize or become elevated, as iron overload is potentially harmful. 1, 5

• Iron supplementation with normal or high ferritin values is not recommended and may cause harm 1, 5
• Target ferritin levels should be maintained above 30 ng/mL but below 800 ng/mL in most patients 1
• Transferrin saturation should be kept below 50% to avoid iron overload 1