From the Guidelines
Normal ferritin (375) with low TIBC suggests iron overload rather than iron deficiency, and I recommend further evaluation with a transferrin saturation test and possibly genetic testing for hereditary hemochromatosis, especially if there are symptoms like fatigue, joint pain, or liver dysfunction. This pattern is consistent with conditions like hemochromatosis, chronic inflammation, or liver disease. Ferritin is an iron storage protein that typically rises when iron levels are high, while TIBC (Total Iron Binding Capacity) measures the blood's capacity to bind iron via transferrin. Low TIBC indicates that transferrin is already saturated with iron or that there's reduced transferrin production.
According to the most recent study 1, the goal ferritin is 50 ng/mL, regardless of sex at birth, and a TSAT <20% has high sensitivity for diagnosing absolute or functional iron deficiency. However, in this case, the normal ferritin level and low TIBC suggest iron overload.
The study also mentions that 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 ID and IDA. However, the most recent and highest quality study 1 should be prioritized, and it recommends avoiding iron supplements as they could worsen potential iron overload.
Some key points to consider:
- Ferritin levels can be elevated in inflammatory conditions, making it less reliable for diagnosing iron deficiency 1
- TSAT <20% has high sensitivity for diagnosing absolute or functional iron deficiency 1
- sTfR can be useful in diagnosing iron deficiency in patients with inflammatory conditions, but it is not always available and has its own limitations 1
- Reticulocyte Hb content can be a direct assessment of the functional availability of iron to the erythropoietic tissue, but it is not always available and can be abnormal in inflammation and thalassemia 1
In terms of management, if hemochromatosis is confirmed, treatment typically involves therapeutic phlebotomy (blood removal) to reduce iron levels. For inflammatory conditions causing this pattern, treating the underlying inflammation would be the priority. Dietary modifications to reduce iron intake might be recommended depending on the diagnosis.
From the Research
Iron Deficiency Diagnosis
- The patient's ferritin level is 375, which is considered normal, and the Total Iron Binding Capacity (TIBC) is low 2.
- According to the study published in the Journal of the College of Physicians and Surgeons--Pakistan, serum ferritin is the gold standard for diagnosing iron deficiency, with a specificity of 99% and sensitivity of 80% at a concentration of 30 ng/ml 2.
- The same study found that serum iron and TIBC give no additional information in the diagnosis of iron deficiency anemia and are redundant if serum ferritin is available 2.
Interpretation of Test Results
- A low TIBC can indicate iron overload or an inflammatory condition, rather than iron deficiency 3, 2.
- The patient's normal ferritin level suggests that they do not have iron deficiency anemia, despite the low TIBC 3.
- It is essential to consider other potential causes of low TIBC, such as inflammation or liver disease, and to evaluate the patient's overall clinical presentation and medical history 3.