Terminal Deoxynucleotidyl Transferase
What is TdT?
The Terminal Deoxynucleotidyl Transferase (TDT) test is performed to classify lymphomas and leukemias, to differentiate between lymphoblastic and non-lymphoblastic leukemia, to diagnose acute lymphoblastic leukemia, lymphoblastic lymphomas and lymphoid blast crisis of CML (Chronic Myelgenous Leukemia).
Why is TdT done?
The test is performed when a patient exhibits symptoms of leukemia such as-
>Swollen lymph nodes
>Unexplained weight loss
>Loss of appetite
Interpreting TdT results
The results depend upon the stain used for the classification and distinction of leukemias and lymphomas. So, a positive result is indicated by the presence of positive staining of the ALL B-cells and negative staining, i.e., no staining in case of absence of TdT positive cells.