Evaluation of Non-Hemoglobin-Bound Iron Accumulation in Hemolysates of Thalassemia Patients

Thalassemia refers to a group of blood disorders characterized by a decrease or absence of the synthesis of one or more normal globin chains. Depending on their clinical severity and transfusion requirements, they can be divided into transfusion-dependent and non-transfusion-dependent thalassemias. In patients with beta-thalassemia major, Hb A synthesis is very low, and Hb F constitutes more than 80% of total hemoglobin. These patients are often transfusion-dependent to ensure tissue oxygenation and suppress ineffective erythropoiesis. Transfusion-dependent patients also need to start iron chelation therapy after a period to prevent iron accumulation in the body. While procedures such as liver biopsy and cardiac MRI (magnetic resonance imaging) exist to directly determine tissue iron accumulation, these procedures are invasive, time-consuming, costly, and require a suitable environment. Therefore, the decision to start iron chelation therapy and adjust the dosage is often made by monitoring ferritin levels, which indicate tissue iron accumulation. Serum ferritin is the most commonly used technique for indirectly indicating body iron stores.

Iron accumulation in the body due to frequent transfusions affects not only tissues such as the liver, heart, and nervous system, but also erythroid cells. While previous studies have frequently measured plasma iron not bound to transferrin, also known as labile plasma iron, there are also publications analyzing intracellular labile iron by staining with calcein and using flow cytometry. Another study measured free iron within erythrocytes using HPLC (high-pressure liquid chromatography). However, both HPLC and flow cytometry are expensive and difficult techniques requiring technician expertise and are not available in every laboratory. In our study, we aim to modify the colorimetric method used for traditional iron measurement and measure hemoglobin-free iron in hemolysate samples obtained from erythrocytes. In simpler terms, we aim to detect iron accumulation in the erythrocytes of thalassemia patients who receive frequent transfusions. As is known, serum ferritin monitoring is a parameter that influences the decision to start iron chelation therapy and the treatment dose in thalassemia patients. However, serum ferritin monitoring has some serious disadvantages. Serum ferritin is an indirect indicator of iron overload, showing a nonlinear response to high iron overload; the absence of a decrease in serum ferritin during follow-up does not preclude this response. Furthermore, ferritin is a positive acute phase reactant, and serum levels increase in many cases, making it difficult to differentiate whether the increase in thalassemia patients is due to accumulation or infection. In our study, we aim to directly assess changes in iron overload at the cellular level, as opposed to ferritin, by measuring intracellular iron that is not bound to hemoglobin.