Background: A false positive sweat test in patients with deficiency of glucose-6-phosphate-1-dehydrogenase (EC 126.96.36.199; G6PD) is repeatedly reported.
Methods: Sweat chloride or conductivity was measured in eleven patients with G6PD deficiency.
Results:Mean chloride level (n=8, median age 9.2 years, range 1.9-48.5) was 18.8 ±9.6 mmol/l and, mean sodium level 26.0 ±10.0 mmol/l respectively, and mean conductivity (n=3, median age 6.6 years, range 1.9-40.5) was 34.3 ±6.5 mmol/l.
Conclusion: In sweat of 11 patients with G6PD deficiency we did not find any abnormality. The reason for alleged false positive sweat test in patients with G6PD deficiency is not known and we were unable to identify any original reference. It appears that tables of putative false positive sweat tests in several disease states have been directly "copied and pasted" from one paper or textbook to another without verifying the original literature, a phenomenon one can call "chain citation".