Does a patient with a low iron level and saturation percentage of 29% have Iron Deficiency Anemia (IDA)?

Iron Deficiency Assessment with Iron 63 mg/dL and Saturation 29%

This patient does NOT have iron deficiency anemia (IDA) based on the transferrin saturation of 29%, which exceeds the diagnostic threshold of <20% used in most clinical contexts. However, the diagnosis requires additional information—specifically serum ferritin and hemoglobin levels—to make a definitive determination.

Diagnostic Criteria for Iron Deficiency

The diagnosis of iron deficiency depends critically on the clinical context and presence of inflammation:

In Patients Without Inflammation

• Absolute iron deficiency is defined by transferrin saturation <16% and serum ferritin <12 ng/mL in otherwise healthy individuals 1
• In the absence of inflammation, serum ferritin <30 μg/L or transferrin saturation <16% defines iron deficiency 1
• For cancer patients, absolute iron deficiency is indicated by ferritin <30 ng/mL and transferrin saturation <15% 1

In Patients With Inflammation or Chronic Disease

• Absolute iron deficiency in chronic kidney disease (CKD) patients requires serum ferritin <100 ng/mL AND transferrin saturation <20% 1
• In inflammatory bowel disease with inflammation present, serum ferritin up to 100 μg/L may still reflect iron deficiency 1
• Functional iron deficiency occurs when transferrin saturation is <20% despite ferritin levels between 100-800 ng/mL 1

Analysis of This Patient's Values

Your patient's transferrin saturation of 29% is ABOVE the diagnostic threshold of <20% used across multiple guidelines 1. This makes iron deficiency less likely, though not impossible:

• The transferrin saturation of 29% suggests adequate iron availability for erythropoiesis in most clinical contexts 1
• However, transferrin saturation alone is not perfectly sensitive or specific—it must be interpreted alongside serum ferritin 1
• The serum iron level of 63 mg/dL provides limited diagnostic value without knowing the total iron binding capacity (TIBC), though the calculated saturation is already provided 1

Critical Missing Information

You MUST obtain the following to definitively diagnose or exclude IDA:

• Serum ferritin level: This is the most powerful single test for iron deficiency 1. Without this value, the diagnosis remains incomplete
• Hemoglobin/hematocrit: IDA requires BOTH iron deficiency AND anemia (hemoglobin two standard deviations below normal) 2
• Inflammatory markers (CRP, ESR): Ferritin is an acute phase reactant and can be falsely elevated in inflammation, making interpretation context-dependent 1
• Clinical context: Presence of chronic kidney disease, heart failure, inflammatory bowel disease, or malignancy significantly alters diagnostic thresholds 1

Clinical Interpretation Algorithm

Step 1: Determine if anemia is present

• Obtain hemoglobin level—IDA cannot be diagnosed without confirmed anemia 3, 2

Step 2: Assess for inflammation/chronic disease

• Check CRP, ESR, or clinical evidence of chronic inflammatory conditions 1
• This determines which ferritin threshold to apply

Step 3: Interpret ferritin in context

• If no inflammation: Ferritin <30 ng/mL indicates iron deficiency 1, 3
• If inflammation present: Ferritin <100 ng/mL indicates iron deficiency 1
• Ferritin 30-100 ng/mL with inflammation suggests mixed iron deficiency and anemia of chronic disease 1

Step 4: Integrate transferrin saturation

• Your patient's TSAT of 29% argues AGAINST iron deficiency in most contexts 1
• However, some patients with TSAT >20% may still be functionally iron deficient and respond to iron therapy 1

Common Pitfalls to Avoid

• Do not diagnose IDA based on transferrin saturation alone—ferritin is essential and more reliable 1
• Do not use general population thresholds in patients with CKD, heart failure, or IBD—these conditions require higher ferritin cutoffs (up to 100 ng/mL) 1
• Do not assume normal iron stores based on a single normal parameter—both ferritin and transferrin saturation can be misleading in isolation 1
• Remember that ferritin is an acute phase reactant—it can be falsely elevated by inflammation, infection, malignancy, or liver disease, masking true iron deficiency 1

Provisional Assessment

Based solely on the transferrin saturation of 29%, this patient is unlikely to have iron deficiency by standard criteria 1. However, you cannot definitively exclude IDA without knowing the serum ferritin and hemoglobin levels 1, 3. The lower the ferritin level, the higher the likelihood of iron deficiency despite the borderline-adequate transferrin saturation 1.