This guideline is an update of the first G6PD guideline [The Assessment of Glucose‐6‐Phosphate Dehydrogenase Deficiency; prepared by the General Haematology Task Force, 1991]. Data from recent External Quality Assessment (EQA) exercises show that there is continued variation in both the results obtained and laboratory practice and this may be sufficient to affect clinical outcome. The guideline is for use by staff working in diagnostic laboratories and is intended to promote the harmonisation of analytical methods through sharing best practice in the diagnosis of G6PD deficiency.

Declaration of Interests

The BSH paid the expenses incurred during the writing of this guidance. None of the authors had conflicts of interest to declare. All authors have made a declaration of interests to the BSH and Task Force Chairs which may be viewed on request.