Management of Elevated UIBC (369)
An elevated UIBC of 369 indicates iron deficiency, and you must confirm this diagnosis with serum ferritin and transferrin saturation, then initiate iron replacement therapy while simultaneously investigating for underlying gastrointestinal blood loss or malabsorption as the cause. 1
Confirm Iron Deficiency
- Serum ferritin is the most powerful single test for iron deficiency, with levels <30 ng/mL diagnostic in the absence of inflammation 1
- Transferrin saturation <20-30% supports the diagnosis of iron deficiency 1
- Elevated UIBC (total iron-binding capacity minus serum iron) reflects increased transferrin levels attempting to capture more iron, consistent with depleted iron stores 2
- If iron studies remain equivocal, a therapeutic trial of oral iron for 3 weeks with hemoglobin rise ≥10 g/L confirms true iron deficiency 1
Investigate the Underlying Cause
All adults with confirmed iron deficiency require gastrointestinal investigation unless there is obvious non-GI blood loss, as GI malignancies commonly present this way 1
Initial Workup
- Take detailed history focusing on: NSAID/aspirin use (stop if possible), dietary iron intake, menstrual blood loss in premenopausal women, GI symptoms, family history of bleeding disorders or celiac disease 1
- Perform urinalysis to exclude urinary blood loss 1
- Screen for celiac disease with tissue transglutaminase antibody, as 3-5% of iron deficiency cases are due to celiac disease 1
Endoscopic Evaluation
- Perform bidirectional endoscopy (gastroscopy and colonoscopy) as first-line investigation in men and postmenopausal women 1
- Upper endoscopy reveals a cause in 30-50% of patients and should include small bowel biopsies to detect celiac disease 1
- Colonoscopy must be performed even if upper endoscopy is positive (unless carcinoma or celiac disease found), as dual pathology occurs in 10-15% of cases 1
- Do not accept minor findings like erosions, esophagitis, or aphthous ulceration as the sole cause without completing lower GI evaluation 1
Initiate Iron Replacement Therapy
Oral Iron (First-Line)
- Start ferrous sulfate 325 mg daily or on alternate days as first-line therapy 3, 4
- Each 325 mg tablet contains 65 mg elemental iron 3
- Oral iron is cheap, safe, and effective for most patients 5, 4
- Expect hemoglobin rise ≥10 g/L within 2 weeks if true iron deficiency 1
Intravenous Iron (Specific Indications)
Consider IV iron for: 4
- Oral iron intolerance or side effects
- Malabsorption (celiac disease, post-bariatric surgery, inflammatory bowel disease)
- Chronic inflammatory conditions (chronic kidney disease, heart failure, IBD, cancer) where oral absorption is impaired
- Ongoing blood loss exceeding intestinal absorption capacity
- Pregnancy (second and third trimesters)
- Transfusion-dependent iron deficiency anemia 1
Further Investigation if Initial Workup Negative
If bidirectional endoscopy is negative and iron deficiency persists or recurs despite adequate replacement: 1
- Capsule endoscopy is the preferred test for small bowel examination, highly sensitive for mucosal lesions 1
- Consider CT/MR enterography as complementary investigation for inflammatory or neoplastic small bowel disease 1
- Small bowel radiology rarely useful unless Crohn's disease suspected 1
- Enteroscopy may detect and treat small bowel angiodysplasia in transfusion-dependent cases 1
Common Pitfalls to Avoid
- Do not assume dietary deficiency alone explains iron deficiency—full GI investigation is still required even with poor dietary intake 1
- Do not stop investigation after finding minor upper GI lesions—always complete lower GI evaluation 1
- Ferritin may be falsely normal in inflammatory states (acute phase reactant)—use transferrin saturation <20% to help diagnose iron deficiency in these cases 1, 6
- Monitor hemoglobin after iron replacement—failure to respond or recurrence warrants further small bowel investigation 1