What is the management plan for a patient with a ferritin level indicating low iron stores, specifically a ferritin level of 28?

Management of Ferritin 28 μg/L

A ferritin level of 28 μg/L indicates depleted iron stores requiring oral iron supplementation, even if hemoglobin is normal, and warrants investigation for the underlying cause of iron loss. 1

Diagnostic Interpretation

• Ferritin 28 μg/L falls below the 30 μg/L threshold that generally indicates low body iron stores, representing Stage 1 iron deficiency where stores are depleted before anemia develops. 1, 2

• This level has 92% specificity for iron deficiency when using the 45 μg/L cutoff as the optimal sensitivity-specificity balance, making the diagnosis highly reliable. 1

• Check complete blood count (CBC) immediately to assess for anemia and evaluate mean cell volume (MCV) and mean cell hemoglobin (MCH) for microcytosis and hypochromia. 1

• Calculate transferrin saturation (TSAT) using the formula: (serum iron × 100) ÷ total iron-binding capacity; expect TSAT <16-20%, which confirms impaired iron delivery to bone marrow. 2

• Measure inflammatory markers (CRP or ESR) to rule out inflammation that could falsely elevate ferritin and mask even more severe iron deficiency. 1, 2

Immediate Treatment

Initiate oral iron supplementation immediately without waiting for investigation results. 2

• Prescribe ferrous sulfate 324 mg (65 mg elemental iron) once daily or every other day. 3, 2

• Alternate-day dosing (60 mg elemental iron every other day) may improve absorption and reduce gastrointestinal side effects compared to daily dosing. 2

• Take on an empty stomach for optimal absorption, or with meals if gastrointestinal symptoms (constipation, nausea, diarrhea) occur. 2

• Target ferritin >100 ng/mL to fully restore iron stores and prevent recurrence, not just normalization of hemoglobin. 2

Investigation Algorithm

The extent of investigation depends on patient demographics and risk factors:

For Premenopausal Women:

• GI investigation is NOT mandatory unless red flags are present. 2

• Assess menstrual blood loss history first, as heavy or prolonged menstruation is the most common cause in this population. 2

• Screen for celiac disease with tissue transglutaminase antibodies (tTG), as it is present in 3-5% of iron deficiency cases. 2

• Test for H. pylori non-invasively (stool antigen or urea breath test). 2

• Reserve bidirectional endoscopy for:

  • Age ≥50 years (higher colorectal cancer risk) 2
  • GI symptoms (abdominal pain, change in bowel habits, blood in stool) 2
  • Positive celiac or H. pylori testing requiring confirmation 2
  • Failure to respond to adequate oral iron after 8-10 weeks 2
  • Strong family history of colorectal cancer 2

For Men and Postmenopausal Women:

• Investigation should be considered at any level of anemia in the presence of iron deficiency, as the case is stronger for serious underlying GI pathology. 1

• Bidirectional endoscopy (upper and lower) is generally warranted to exclude GI malignancy and other pathology. 1

• Screen for celiac disease and H. pylori as above. 2

Follow-Up and Monitoring

• Repeat CBC and ferritin in 8-10 weeks to assess response to treatment. 2, 4

• Expected response: hemoglobin should rise by 1-2 g/dL and ferritin should increase if compliance is adequate. 5

• If no improvement after 8-10 weeks, consider:

  • Non-compliance with iron supplementation 2
  • Malabsorption (celiac disease, inflammatory bowel disease, H. pylori) 2
  • Ongoing blood loss requiring urgent GI evaluation 2
  • Need for intravenous iron if oral absorption is impaired 2

• For patients with recurrent low ferritin (menstruating females, vegetarians, athletes, blood donors), screen ferritin every 6-12 months. 2

• Do not continue daily iron supplementation once ferritin normalizes (>100 ng/mL), as this is potentially harmful and can lead to iron overload. 2, 4

Critical Pitfalls to Avoid

• Do not assume ferritin 28 μg/L is "borderline normal" and defer treatment—this represents depleted iron stores requiring intervention. 1, 2

• Do not wait for anemia to develop before treating—iron deficiency without anemia causes significant symptoms including fatigue, reduced exercise tolerance, and impaired cognitive function. 2, 4

• Do not perform extensive GI investigation in young, asymptomatic premenopausal women with heavy menses, as the yield is extremely low (0-6.5%). 2

• Do not overlook celiac disease screening, which is easily missed without serologic testing and present in 3-5% of cases. 2

• In the presence of inflammation (elevated CRP/ESR), ferritin thresholds shift upward to <100 μg/L, meaning ferritin 28 μg/L with inflammation indicates even more severe iron deficiency. 2