Background: A false-positive sweat test in patients with deficiency of glucose-6-phosphate-1-dehydrogenase (EC 18.104.22.168; G6PD) is repeatedly reported.
Methods: Sweat chloride or conductivity was measured in 11 patients with G6PD deficiency.
Results: Mean (SD) chloride level (n = 8, median age 9.2 years, range 1.9–48.5) was 18.8 (9.6 mmol/l) and, mean (SD) sodium level was 26.0 (10.0 mmol/l), respectively, and mean (SD) 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”.
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Competing interests: None.