Blood analysis to investigate functional iron deficiency - a condition in which the body has stored iron, but where the iron is not available for blood formation and oxygen transport. Functional iron deficiency is a common cause of fatigue and decreased energy that is often not detected with standard iron tests.
In functional iron deficiency, ferritin may be normal or elevated, while the body suffers from a true iron deficit at the cellular level. The iron is then "locked up" in the body and cannot be used effectively, often as a result of inflammation, infection or chronic disease.
The analysis therefore focuses not only on how much iron is stored, but on how the iron is actually used in the body. By combining several complementary markers, functional iron deficiency can be identified even when traditional iron tests appear normal.
What is functional iron deficiency?
Functional iron deficiency means that the body's iron stores are not depleted, but that the iron cannot be mobilized for blood formation. This is often seen in inflammatory conditions, chronic diseases, long-term stress or infection, where the body's regulation of iron metabolism is altered.
What is analyzed in the test?
The test includes several key markers that together can identify the pattern of functional iron deficiency:
- Transferrin saturation (TSAT) – shows how large a proportion of the iron is biologically available.
- Transferrin receptor (P-sTfR) – reflects the cells' need for iron.
- Ferritin – shows the body's iron stores, but is affected by inflammation.
- Iron – the amount of circulating iron in the blood.
- TIBC – iron-binding capacity.
- Blood status (Hb, MCV, EPK) – information about blood formation and red blood cell size.
- Reticulocytes – reflects the bone marrow's current production of red blood cells.
- RDW – shows the variation in red blood cell size and may be elevated in iron deficiency.
Typical test pattern in functional iron deficiency
- Low transferrin saturation (<15–20%).
- Normal or elevated ferritin.
- Elevated transferrin receptor (P-sTfR).
- Low S-iron.
- Normal or low TIBC.
This pattern indicates that iron is present in the body but is not available for effective blood formation.
Who is the test suitable for?
- You who have long-term fatigue or reduced energy.
- You who have normal iron tests but persistent symptoms.
- You with inflammatory or chronic medical conditions.
- You who have not had an effect from iron supplements.
- You who want to investigate iron metabolism at the cellular level.
Sample collection and medical assessment
The sample is taken as a regular venous blood sample. All test results are reviewed by a licensed physician who provides a personal medical opinion with interpretation and recommendations if necessary.
