Increase of hemoglobin A2 in human immunodeficiency virus-1-infected patients treated with zidovudine

We observed increased hemoglobin A₂ (HbA₂) levels in an asymptomatic human immunodeficiency virus-1 (HIV¹) patient with no previous history of β-thalassemia. He was treated only with zidovudine (AZT). In an attempt to understand this observation, a retrospective study was initiated to determine whether mean HbA₂ levels are higher in AZT-treated patients than in subjects not receiving this drug and to assess if other hematologic alterations are associated with elevated HbA₂. One hundred fifty-one HIV-positive cases were investigated; AZT was administered to 81 of them. The mean value of HbA₂ was 0.032 (SD ±0.005) for the treated group vs. 0.027 (SD ±0.004) for the controls. This difference was highly significant (P < 0.001). Twenty-four patients (31%) in the treated group had elevated HbA₂ levels vs. none in the controls. Bone marrow toxicity seemed to be more significant in patients with heightened HbA₂ values, and HbA₂ levels did not increase with CDC clinical stage. We conclude that AZT may be linked to high HbA₂ levels in some patients.