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Table 1 The effect of storage temperature and duration on dried blood spot estimation of GPD enzyme activity

From: Population screening for glucose-6-phosphate dehydrogenase deficiencies in Isabel Province, Solomon Islands, using a modified enzyme assay on filter paper dried bloodspots

Storage temperature Baseline G6PD enzyme activity (%) that results in a sample testing severely deficient (< 10% activity) at the designated storage temperature and duration Decay in enzyme activity
  Day 1 Day 5 Day 10 Day 14  
4°C 10% 10% 15% 15% ~ 5% by Day 10
25°C 10% 15% 25% 25% ~ 5% by Day 5
      ~ 15% by Day 10
37°C 10% 15% 25% 50% ~ 5% by Day 5
      ~ 15% by Day 10
      ~ 40% by Day 14
  1. The reliability of G6PD assays on blood spots stored for different times at different temperatures was assessed with bloodspots containing differing amount of reference G6PD enzyme activity. The table shows the % enzyme activity that tested as deficient (≤ 10% activity) at days 1, 5, 10 and 14 when stored at 4°C, 25°C and 37°C. The decay in enzyme activity represents the difference between the original enzyme activity and the activity when retested.