G6PD Deficiency in the Newborn Guidelines

Updated: Jun 25, 2020
  • Author: Lawrence C Wolfe, MD; Chief Editor: George T Griffing, MD  more...
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Guidelines

Guidelines Summary

British Society for Haematology

Guidelines on the laboratory diagnosis of G6PD deficiency, published in January 2020 by the British Society for Haematology, include the following [38] :

  • Screening tests should not be relied on for the diagnosis of female patients; G6PD activity should be measured directly by quantitative spectrophotometric assay
  • An abnormal or borderline screening test means that a quantitative assay must be performed
  • To be certain that a G6PD-deficiency diagnosis is not missed, re‐assay after a hemolytic episode of unknown cause
  • Because the G6PD reaction is temperature‐dependent, an accurate cuvette temperature is essential
  • Controls should be run with every sample batch; it is preferable to use a normal and deficient sample obtained through a commercial company than to employ an in‐house control
  • White cells, which contain a significant amount of G6PD, ideally should be removed before assay; especially consider removal of white cells with a cellulose/”real” cotton wool column prior to assay if the count is above the lab’s reference interval upper limit
  • If performed only infrequently, carry out assays in duplicate; the duplicates’ results, on normal samples, should be within 0.5 IU/g of hemoglobin of each other
  • Employ in-house testing to establish a laboratory reference range
  • Assay absorbance should be checked to see that it increases in a linear fashion (which may take a minute or two to achieve), and, for non-kit methods, the absorbance should be measured over 10 minutes at 20-second intervals
  • Measurement of the hemoglobin concentration of the hemolysate is equal in importance to measurement of the enzyme activity, since both measurements have a comparable impact on the final result; this applies similarly to well-mixed whole blood where a kit indicates such use
  • Interpret the final G6PD activity in light of the reticulocyte count measured on the same sample
  • Participation in an accredited external quality assessment scheme is important for laboratories undertaking these screening tests and assays