What is the diagnosis and recommended management for a patient with mild iron deficiency, normal hemoglobin and hematocrit, and negative autoimmune antibody panel?

Diagnosis: Early Iron Deficiency Without Anemia

This patient has early iron deficiency without anemia, characterized by low ferritin (24 μg/L), low iron saturation (18%), and elevated transferrin (344 mg/dL), despite normal hemoglobin and hematocrit. 1

Laboratory Profile Interpretation

• The combination of low transferrin saturation (<20%), elevated TIBC (399 μg/dL), elevated UIBC (328 μg/dL), and elevated transferrin represents a compensatory response where the body increases iron-carrying proteins to mobilize more iron for erythropoiesis 1

• Ferritin of 24 μg/L confirms iron deficiency, as levels <30 μg/L in the absence of inflammation indicate true iron deficiency 2

• The MCV of 97 fL (at upper limit of normal) and normal hemoglobin (13.2 g/dL) indicate that anemia has not yet developed, but iron stores are depleted 3

• Normal CRP and negative autoimmune panel exclude inflammatory conditions that could confound ferritin interpretation 2

Recommended Management

Immediate Treatment

• Initiate oral iron supplementation with ferrous sulfate 200 mg three times daily (or ferrous gluconate/ferrous fumarate as alternatives) 2

• Take iron on an empty stomach with vitamin C (ascorbic acid) to enhance absorption, avoiding concurrent tea, coffee, calcium, or antacids 2, 1

• Continue iron supplementation for three months after correction of iron parameters to replenish body stores 2

Investigation of Underlying Cause

For this female patient, the following causes must be evaluated:

• Menstrual blood loss (menorrhagia) is the most common cause in premenopausal women, occurring in 5-10% of this population 2

• Dietary insufficiency should be assessed through detailed dietary history, particularly vegetarian/vegan diets 1

• Gastrointestinal blood loss must be considered, especially if menstrual history does not explain the deficiency 2, 1

• Screen for celiac disease with tissue transglutaminase (tTG) antibody testing, as coeliac disease has ~5% pretest probability in iron deficiency 2, 1

• Assess for NSAID use, which is a common cause of occult GI blood loss 2

Monitoring and Follow-up

• Monitor hemoglobin and ferritin at 3-4 weeks; expect hemoglobin to rise by 2 g/dL if treatment is effective 2

• Once iron parameters normalize, monitor hemoglobin and ferritin every three months for one year, then annually 2

• If hemoglobin or ferritin falls below normal during follow-up, resume oral iron and consider further investigation 2

Critical Pitfalls to Avoid

• Do not rely solely on serum iron levels (71 μg/dL in this case), as they have significant diurnal variation and can be normal in early iron deficiency 1, 3

• Do not overlook iron deficiency in patients with normal hemoglobin; this patient demonstrates that iron depletion precedes anemia development 1, 3

• Do not discontinue iron therapy prematurely once hemoglobin normalizes; continue for three months to replenish stores 2, 1

• Failure to respond to oral iron (no rise in hemoglobin after 3-4 weeks) suggests poor compliance, continued blood loss, malabsorption, or misdiagnosis 2

When to Consider Parenteral Iron

• Parenteral iron should only be used if there is intolerance to at least two oral iron preparations or documented non-compliance 2

• Intravenous iron is preferred in patients with clinically active inflammatory bowel disease, hemoglobin <10 g/dL, or previous intolerance to oral iron 2