Ferritin 55 μg/L in Acute Ulcerative Colitis: Interpretation
A ferritin level of 55 μg/L in a patient with acute ulcerative colitis indicates iron deficiency, as this value falls within the diagnostic range for iron deficiency in the presence of inflammation (ferritin up to 100 μg/L may still be consistent with iron deficiency). 1
Understanding Ferritin Interpretation in Inflammatory States
The critical principle is that ferritin interpretation depends entirely on the presence or absence of inflammation 1:
- Without inflammation: Ferritin <30 μg/L defines iron deficiency 1
- With inflammation (as in acute UC): Ferritin up to 100 μg/L may still indicate iron deficiency 1
- Your patient's ferritin of 55 μg/L falls squarely in this "gray zone" of 30-100 μg/L 1
Most Likely Diagnosis: Combined Iron Deficiency
When ferritin levels are between 30-100 μg/L in the setting of inflammation, a combination of true iron deficiency and anemia of chronic disease is likely. 1, 2
This mixed picture is extremely common in ulcerative colitis patients, occurring in approximately 23.5% of cases according to recent data 3.
Confirm the Diagnosis with Additional Testing
To definitively characterize the anemia, obtain these specific tests 1:
- Transferrin saturation (TSAT): If <16-20%, this supports iron deficiency even with inflammation present 1, 4
- C-reactive protein (CRP): Confirms active inflammation and guides ferritin interpretation 1, 2
- Complete blood count with MCV and RDW: Helps distinguish iron deficiency from other causes 1
- Soluble transferrin receptor (sTfR): The most reliable test in inflammatory states—elevated in iron deficiency, normal/low in pure anemia of chronic disease 1, 2
Clinical Context Matters
In acute UC specifically, research shows that optimal diagnostic thresholds differ from general guidelines 4:
- For UC patients with CRP <10 mg/L: Ferritin threshold of 65 μg/L has sensitivity 0.78 and specificity 0.76 for iron deficiency 4
- For UC patients with CRP >10 mg/L: Ferritin threshold of 80 μg/L has sensitivity 0.75 and specificity 0.82 4
- Your patient's ferritin of 55 μg/L is below both thresholds, strongly suggesting iron deficiency 4
Treatment Implications
Iron supplementation is recommended in all ulcerative colitis patients when iron deficiency anemia is present. 1
The primary therapeutic approach should be 1, 2:
- Treat the underlying UC inflammation first—this is the foundation of management 2
- Provide iron supplementation once iron deficiency is confirmed 1
- Both intravenous ferric carboxymaltose and oral sucrosomial iron show similar effectiveness in UC patients in remission 5
Common Pitfall to Avoid
Do not assume normal iron stores based on ferritin >30 μg/L in the setting of acute inflammation. 1 This is the most common diagnostic error—ferritin acts as an acute phase reactant and can be falsely elevated by inflammation, masking true iron deficiency. In your patient with acute UC, the ferritin of 55 μg/L should be interpreted as consistent with iron deficiency, not adequate iron stores. 1, 4