Relationship between Carnitine Deficiency and Tyrosine Kinase Inhibitor Use in Patients with Chronic Myeloid Leukemia

Background: Some chemotherapeutic agents cause carnitine deficiency, which confers general fatigue; however, there is no study on carnitine deficiency in patients with chronic myeloid leukemia (CML) during tyrosine kinase inhibitor (TKI) therapy. Objective: This study investigated carnitine concentrations in patients with CML treated with TKIs. Method: This study included patients with well-controlled CML. Total carnitine and free carnitine concentrations were evaluated using the enzyme cycling method. The Brief Fatigue Inventory (BFI) and Cancer Fatigue Scale (CFS) were used to assess general fatigue developed during TKI therapy. Results: Fifty-five patients on TKIs were included; 12 (21.8%) had low free carnitine concentrations. Free carnitine concentrations were higher in men than in women. Younger age was closely associated with lower free carnitine concentrations. TKI type, TKI dose, treatment response, or therapy duration were not associated with free carnitine concentrations. None of the scores (the global fatigue score with the BFI and CFS score) correlated with carnitine concentrations. Concentrations of free carnitine in the treatment-free remission group were slightly higher than those in the TKI group, with only 9.1% having a low concentration of free carnitine. Conclusion: Carnitine deficiency is probably not a major cause of general fatigue, but may occur in patients with CML receiving TKIs.