Table 1 Calculating G6PD activity

The WHO has defined a total of five classes (I–V) of G6PD activity [16]:

 • Severe deficiency (<10 % activity, chronic, non-spherocytic, haemolytic anaemia)

 • Severe deficiency (<10 % activity, intermittent haemolysis)

 • Mild deficiency (10–60 % activity, haemolysis with stressors only)

 • Normal enzyme variant (60–150 % activity, no clinical sequelae)

 • Increased enzyme activity (>150 % activity, no clinical sequelae)

100 % G6PD activity is based on the adjusted quantitative (iU/gHb or U/10¹² RBC) median of all male samples from a defined sample set [9]. In a first step the median G6PD activity of samples from all male participants is calculated. Second, all samples with ≤10 % G6PD activity of the median are excluded. Third, the median is re-calculated based on the remaining samples, the adjusted male median. The adjusted male median is defined as 100 % G6PD activity and all samples are grouped accordingly