From the Guidelines
Iron studies typically include a complete blood count (CBC) and iron parameters such as ferritin, percent transferrin saturation (TSAT), and serum iron.
Key Components of Iron Studies
- Ferritin: reflects iron stores, with a goal of 50 ng/mL in the absence of inflammation 1
- Transferrin saturation (TSAT): calculated by dividing serum iron by total iron binding capacity (TIBC), with a TSAT <20% indicating iron deficiency 1
- Serum iron: measures the amount of iron in the blood
- Total iron binding capacity (TIBC): measures the capacity of transferrin to bind iron
- Complete blood count (CBC): includes hemoglobin, hematocrit, mean cell volume, and red blood cell distribution width
Additional Tests
- Soluble transferrin receptor (sTfR): may be used in patients with inflammatory conditions where ferritin is unreliable 1
- Reticulocyte hemoglobin content (CHr) or reticulocyte hemoglobin equivalent (RET-He): direct assessments of functional iron availability 1 These tests help diagnose and monitor iron deficiency, as well as assess the response to iron replacement therapy 1.
From the Research
Laboratory Tests for Iron Study
The following laboratory tests are included in an iron study:
- Ferritin: reflects the iron stores 2, 3, 4, 5
- Transferrin saturation (TSAT): measures the percentage of transferrin that is saturated with iron 2, 3, 4
- Zinc protoporphyrin (ZPP): indicates whether the iron deficiency is clinically relevant or not 2
- Sideroblast count: measures the number of red blood cells that contain granules of iron 2
- Reticulocyte hemoglobin content (CHr): measures the amount of hemoglobin in reticulocytes 3
- Soluble transferrin receptor (sTfR)/log ferritin ratio: measures the level of soluble transferrin receptor and ferritin in the blood 3
- Hemoglobin concentration: measures the amount of hemoglobin in the blood 2, 3, 5, 6
- Red cell indices: measures the size and shape of red blood cells 2
- Mean corpuscular volume (MCV): measures the average volume of red blood cells 5
- Mean cell hemoglobin concentration (MCHC): measures the average concentration of hemoglobin in red blood cells 5
- Serum iron: measures the amount of iron in the blood 5
Interpretation of Laboratory Tests
The interpretation of these laboratory tests is crucial in diagnosing iron deficiency and its severity. The tests should be used in combination to efficiently identify patients with iron deficiency 3. The severity of iron deficiency can be assessed by measuring the extent of iron depletion, iron-deficient erythropoiesis, and iron-deficiency anemia 2.