What is the diagnosis and treatment for a patient with low iron levels, elevated Total Iron Binding Capacity (TIBC), and low iron saturation?

Laboratory Analysis: Iron Deficiency Anemia

These laboratory values confirm iron deficiency anemia (IDA), characterized by low iron saturation (13%), elevated TIBC (413 mcg/dL), low serum iron (53 mcg/dL), and borderline-low ferritin (85 ng/mL), requiring oral iron supplementation and investigation of the underlying cause. 1, 2

Interpretation of Laboratory Values

Your iron panel demonstrates a classic pattern of iron deficiency:

• Iron saturation of 13% is below the diagnostic threshold of 16-20%, strongly indicating iron deficiency even with the borderline ferritin level 1, 2
• Elevated TIBC of 413 mcg/dL reflects increased transferrin production as the body attempts to compensate for low iron availability 1, 2
• Low serum iron of 53 mcg/dL combined with high TIBC confirms inadequate iron availability for erythropoiesis 1
• Ferritin of 85 ng/mL appears normal but can be misleading, as ferritin is an acute phase reactant that rises with inflammation and may mask underlying iron deficiency 2
• Transferrin of 289 mg/dL is within normal range but must be interpreted in context of the other abnormal values 1

Diagnostic Classification

This pattern represents functional iron deficiency, where iron stores may be present but cannot be effectively mobilized for hemoglobin synthesis 2. The low transferrin saturation (<20%) with elevated TIBC indicates inadequate iron availability for red blood cell production, even when ferritin appears borderline normal 2.

Treatment Recommendations

First-Line Therapy

Initiate oral iron supplementation immediately as the preferred first-line treatment 2, 3:

• Dosing: 3 mg/kg per day of elemental iron for children, or 60 mg elemental iron tablets daily for adults 4
• Timing: Administer between meals to maximize absorption 4
• Duration: Continue for 2-3 months after hemoglobin normalizes to replenish iron stores 4, 3

Monitoring Response

• Recheck hemoglobin in 4 weeks: An increase of ≥1 g/dL confirms the diagnosis and appropriate response 4, 5
• If no response after 4 weeks: Consider malabsorption, continued blood loss, non-compliance, or alternative diagnosis 4, 5
• Serial ferritin monitoring: In functional iron deficiency, ferritin levels typically decrease during therapy as stores are mobilized 2

Alternative Therapy

Consider intravenous iron if 3, 6:

• Patient cannot tolerate oral iron due to gastrointestinal side effects
• Malabsorption is present (gastric bypass, inflammatory bowel disease)
• Rapid iron repletion is necessary
• Oral iron fails despite compliance 6

Mandatory Evaluation for Underlying Cause

The presence of iron deficiency mandates investigation of the source, as it rarely occurs without an identifiable cause 1, 2:

In Men and Postmenopausal Women

• Gastrointestinal endoscopy is required to evaluate for occult bleeding, starting with colonoscopy if age >50 years 3, 5
• Nine percent of patients older than 65 years with IDA have gastrointestinal cancer 5

In Premenopausal Women

• Assess menstrual blood loss patterns 1, 2
• If menstrual losses do not explain the deficiency, proceed with gastrointestinal evaluation 3

Additional Causes to Investigate

• Dietary insufficiency: Restrictive diets, vegetarian/vegan diets without supplementation 1
• Medications: NSAID use causing occult GI bleeding 1
• Malabsorption: Celiac disease, atrophic gastritis, Helicobacter pylori infection 7
• Other blood loss: Blood donation, high-impact athletics causing hemolysis 1

Additional Testing Needed

Obtain a complete blood count to assess for anemia and determine MCV (mean corpuscular volume) 1:

• Iron deficiency typically presents as microcytic hypochromic anemia 8, 7
• MCV helps differentiate from other causes of anemia 8

Check C-reactive protein to assess for inflammation, which can elevate ferritin and mask true iron deficiency 1, 2

Critical Pitfalls to Avoid

• Do not rely solely on ferritin for diagnosis when transferrin saturation is low; ferritin between 30-100 ng/mL can still represent iron deficiency in the presence of inflammation 2
• Do not dismiss iron deficiency when ferritin appears normal but transferrin saturation is <20% 2
• Do not continue iron indefinitely without monitoring response and investigating the underlying cause 2
• Do not delay endoscopic evaluation in men and postmenopausal women, as malignancy must be excluded 3, 5
• Collect iron studies at consistent times due to diurnal variation in serum iron and transferrin saturation 1, 2