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The sample collection fee is a fixed cost that refers to the visit to the clinic where you submit your sample. The fee is not affected by how many tests you have ordered, but varies depending on the order value:

  • For order values under SEK 350, the sampling fee is SEK 129.
  • For order values between SEK 350 and SEK 1000, the fee is SEK 59.
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TFR

(TfR)

Tansferrin receptor

Transferrin receptor (P-sTfR) is a biomarker that reflects the body's need for iron at the cellular level. The analysis is primarily used to identify iron deficiency and functional iron deficiency, especially in conditions where ferritin is difficult to interpret.

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Contents

What is transferrin receptor (P-sTfR)?

Transferrin receptor (soluble transferrin receptor, sTfR) is a circulating biomarker that reflects the body's need for iron at the cellular level. The transferrin receptor is expressed on the cell surface of most cells, especially in the erythroid cells of the bone marrow, where it enables the uptake of iron via transferrin.

A smaller proportion of the receptor is released into the blood as soluble transferrin receptor (P-sTfR). The concentration in plasma therefore reflects both the iron availability in the tissues and the activity of erythropoiesis.

Physiological function

Iron is transported in the blood bound to transferrin. In order for iron to be taken up by cells, transferrin must bind to the transferrin receptor on the cell membrane. When iron requirements increase or intracellular iron stores decrease, the expression of transferrin receptors increases.

Elevated levels of P-sTfR therefore indicate that the cells are demanding more iron, regardless of the body's total iron stores.

Clinical significance

P-sTfR is used in healthcare as a complement to traditional iron markers, especially in conditions where ferritin is difficult to interpret. The marker is affected to a significantly lesser extent by inflammation compared to ferritin.

Elevated levels are seen primarily in:

  • Iron deficiency.
  • Functional iron deficiency (insufficient iron supply despite normal or high iron stores).
  • Increased erythropoiesis, for example in hemolysis or after bleeding.

Functional iron deficiency

Functional iron deficiency means that iron is stored in the body but is not available for effective blood formation. This is often seen in chronic inflammation, infection, cancer or chronic kidney disease.

In these situations, ferritin may be normal or elevated, while P-sTfR is elevated, making the analysis particularly valuable for identifying hidden or functional iron deficiency.

When is analysis of P-sTfR relevant?

Analysis of transferrin receptor can be particularly useful in:

  • Suspected iron deficiency despite normal or elevated ferritin.
  • Inflammatory or chronic disease states.
  • Investigation of anemia of unclear genesis.
  • Follow-up of iron therapy in case of concomitant inflammation.

Interpretation and Reference Intervals

P-sTfR is analyzed in plasma. The value should always be interpreted together with other iron parameters such as ferritin, iron, transferrin and Hb, and in relation to the clinical picture. The combination of P-sTfR and ferritin (sTfR/log ferritin index) is sometimes used to further improve diagnostics in complex cases of anemia.

The reference range for transferrin receptor (P-sTfR) is 1.7–4.1 mg/L. The reference range may vary slightly between laboratories and should always be interpreted in relation to other iron parameters and the clinical picture.