From the Guidelines
Low transferrin levels in the blood indicate a decreased ability to transport iron throughout the body, which can lead to iron deficiency and potentially anemia or other complications if left untreated. Transferrin is a protein that binds to iron and carries it in the bloodstream to areas where it's needed, such as the bone marrow for red blood cell production. According to the most recent study 1, low transferrin can occur in several conditions, including malnutrition, protein deficiency, liver disease (particularly cirrhosis), kidney disease, inflammation, and certain cancers. It may also be seen in conditions of iron overload like hemochromatosis, where the body has excess iron and reduces transferrin production in response.
Some key points to consider when evaluating low transferrin levels include:
- The frequency of administration and duration of benefit of intravenous iron is dependent on the underlying etiology of the iron deficiency 1
- Laboratory evaluation following IV iron should include a CBC and iron parameters (ferritin, percent transferrin saturation (TSAT)) 4 to 8 weeks after the last infusion 1
- A TSAT <20% has high sensitivity for diagnosing absolute or functional iron deficiency, but a ferritin of <100 ng/mL has a low sensitivity of 35%–48% 1
- Soluble transferrin receptor (sTfR) has been shown to be more sensitive in patients with inflammatory conditions where the ferritin (but not the TSAT) is unreliable for evaluation of iron deficiency and iron deficiency anemia 1
If you have low transferrin levels, your doctor may recommend additional tests to determine the underlying cause, such as liver function tests, kidney function tests, iron studies, or tests for inflammatory markers. Treatment focuses on addressing the underlying condition rather than the transferrin level itself. For example, improving nutrition for malnutrition, treating liver disease, or managing kidney problems. It is essential to address the underlying cause of low transferrin levels to prevent potential complications, such as anemia, and to improve overall health outcomes.
From the Research
Low Transferrin Levels
- A low transferrin level can be an indicator of iron deficiency, but it is not a direct measure of iron status 2, 3.
- Transferrin saturation (TSAT) is calculated by dividing serum iron by total iron-binding capacity (TIBC), and a low TSAT indicates iron deficiency 2.
- However, in patients with chronic kidney disease (CKD), low TIBC can be associated with malnutrition and inflammation, making TSAT a less reliable indicator of iron status 2.
- In such cases, low serum iron can still be a risk factor for anemia, even with normal TSAT 2.
Diagnosis and Treatment
- Iron deficiency anemia can be diagnosed using a combination of laboratory tests, including serum iron, ferritin, TSAT, and mean corpuscular volume 3, 4.
- Treatment of iron deficiency anemia typically involves oral or parenteral iron supplementation, and blood transfusion may be reserved for symptomatic anemia despite iron supplementation 3, 4.
- New parameters, such as red blood cell ferritin, serum transferrin receptor test and index, and hepcidin, have been studied for their utility in indicating true iron deficiency in combination with chronic liver disease 3.
Transferrin Saturation as a Diagnostic Criterion
- Transferrin saturation can be used as a diagnostic criterion for iron deficiency, particularly in combination with ferritin 5.
- A systematic review of the literature found that using transferrin saturation in addition to ferritin can improve the diagnosis of iron deficiency, especially in patients with chronic inflammatory diseases 5.