The human immunodeficiency virus (HIV) constitutes a major public health problem in Botswana with a prevalence of 17.6% 1 in the general population and 31.8% amongst pregnant woman.2,3 Botswana is one of the countries in Africa that has led a very high response to the epidemic through a range of multilevel interventions, including the widespread access to antiretrovirals (ARVs),4,5 and has built capacity to conduct international prevention, treatment and vaccine trials.6 A valid scientific safety evaluation of ARVs and HIV vaccines relies on the availability of locally defined reference values for parameters of clinical interest.