What is the required specimen for confirming a positive G6PD deficiency?

G6PD deficiency is diagnosed through biochemical assays that measure the enzyme's activity in red blood cells. The most reliable specimen for confirming a positive G6PD deficiency is EDTA whole blood. This specimen is preferred because it preserves the integrity of red blood cells, allowing for accurate measurement of G6PD enzyme levels. Whole blood provides a functional assessment of the enzyme's activity directly from the source, which is essential for an accurate diagnosis.

Dried blood spot can be used in certain contexts, particularly in newborn screening programs, but it doesn’t yield the same immediate quantifiable information as EDTA whole blood because of potential degradation during storage and processing. Urine is typically not used for the diagnosis of G6PD deficiency, as it does not contain sufficient G6PD enzyme for assessment. Serum is also not appropriate for this purpose, since the enzyme is present primarily within red blood cells and is not measured in serum. Therefore, EDTA whole blood is the specimen of choice for confirming G6PD deficiency.