The impact of an inaccurate HemoCue® measured Hb is likely to be greater at low Hb concentrations because this may lead to unnecessary referrals for further management of anaemia or unnecessary blood transfusions (with its attendant complications [37]) whilst overreading the true Hb concentration would result in a missed diagnosis of anaemia and no appropriate management of an anaemic patient. This evidence concerns the gene GSTM1 and anemia (phenotype).