Causes of macrocytosis in HIV-infected patients not treated with zidovudine

Objective: Zidovudine is a well known cause of macrocytosis. However, many HIV-infected patients develop macrocytosis even though they do not receive zidovudine. The aim of this case-control study was to evaluate other causes of high mean corpuscular volumes (MCV) in HIV infected patients. Methods: Thirty patients with a MCV greater than or equal to 100 fl (cases) were compared to 60 randomly selected controls with MCV less than or equal to 99 fl, none of them receiving zidovudine, Results: Sex ratio, age, mean CD4, prevalence of alcohol abuse and liver di sease were similar in both groups, Vitamin B12 or folic acid levels were no t decreased in patients with macrocytosis, In contrast, there was an associ ation between macrocytosis and use of stavudine alone or in combination wit h another antiviral drug (28/30 cases, 15/60 controls, odds ratio 40.6 (95% tonfidence interval 5.1-325.2), P< 0.001), The haemoglobin concentration a mong cases (mean 13.5 g/dl) was similar to that of controls (mean 13.0 g/dl ), Conclusions: Stavudine use increase the risk of macrocytosis more than 40-f old in HIV-infected patients who do not receive zidovudine, None of the sta vudine-treated patients, however, developed anaemia or had to interrupt tre atment because of this side effect. (C) 2000 The British Infection Society.