What is the patient's diagnosis based on lab results?

Iron Deficiency Anemia

Based on the laboratory findings showing microcytic anemia (low hemoglobin, low hematocrit, low MCV) with low serum iron, low ferritin, and elevated TIBC/transferrin saturation abnormalities, this patient has iron deficiency anemia. 1, 2

Diagnostic Confirmation

The laboratory pattern is classic for iron deficiency anemia:

• Microcytic anemia (low MCV) with reduced hemoglobin and hematocrit indicates iron-deficient erythropoiesis 2
• Low serum ferritin is the preferred initial diagnostic test and confirms depleted iron stores 1, 2
• Low serum iron with elevated TIBC (total iron-binding capacity) reflects the body's attempt to capture more iron when stores are depleted 3, 2
• Low transferrin saturation further confirms inadequate iron availability for red blood cell production 2

This combination of findings represents stage 3 iron deficiency (iron deficiency anemia), which follows storage iron depletion (stage 1) and iron-deficient erythropoiesis (stage 2) 2.

Critical Next Steps

The most important action is identifying the source of iron loss, as iron deficiency in adults almost always indicates blood loss 3:

• In adult men and non-menstruating women, gastrointestinal blood loss is the primary concern and requires endoscopic evaluation, starting with colonoscopy if age >50 years 1, 3
• In premenopausal women, menstrual blood loss is most common, but gastrointestinal sources must still be excluded if history doesn't support gynecologic losses 1
• 9% of patients over 65 years with iron deficiency anemia have gastrointestinal cancer, making evaluation urgent in older adults 1

Important Caveats

Do not confuse iron deficiency anemia with anemia of chronic disease, which is the most common diagnostic error 3:

• Anemia of chronic disease shows low serum iron BUT normal or low TIBC (not elevated) and normal or elevated ferritin 3
• In hospitalized patients with infection, malignancy, or inflammatory conditions, ferritin can be falsely elevated despite true iron deficiency 2
• When ferritin is 46-99 ng/mL (equivocal range), additional tests (transferrin saturation, serum transferrin receptor) or bone marrow biopsy may be needed 1

Mean corpuscular hemoglobin (MCH), MCHC, and serum iron alone are unreliable markers and should not be used in isolation 4, 5. Always evaluate ferritin and transferrin saturation together 4.

Treatment Approach

Once the source of blood loss is identified and addressed:

• Oral iron supplementation (ferrous sulfate 270 mg/day containing 80 mg elemental iron) is first-line treatment 6
• Expect hemoglobin to increase by 1-2 g/dL within one month of starting therapy 1
• If hemoglobin fails to rise appropriately, consider: malabsorption of oral iron, ongoing blood loss, non-compliance, or concomitant folate/B12 deficiency 1, 3
• Intravenous iron is reserved for malabsorption, intolerance to oral iron, or specific conditions like heart failure with reduced ejection fraction 4

Special Consideration for Diabetic Patients

If this patient has diabetes, be aware that iron deficiency anemia falsely elevates HbA1c levels 6:

• Treatment of iron deficiency can decrease HbA1c by approximately 0.4% without changes in fasting glucose 6
• Do not intensify diabetes treatment based solely on elevated HbA1c in the presence of untreated iron deficiency 6
• Recheck HbA1c after correcting the anemia 6