Ice Pops Can Cause False-Positive Galactomannan Test
WEDNESDAY, July 3 (HealthDay News) -- A case of a false-positive serum aspergillus antigen (galactomannan) test in a patient who underwent a stem-cell transplant and ate flavored ice pops is described in a letter published in the July 4 issue of the New England Journal of Medicine.
Nicolas Guigue, Pharm.D., from Hôpital Saint Louis in Paris, and colleagues describe the case of a 42-year-old women who received a human leukocyte antigen-matched hematopoietic stem-cell transplant from an unrelated donor for a myeloproliferative syndrome, and had an increased galactomannan index at 32 and 34 days after transplantation. The patient had been fasting but began consuming three to four flavored ice pops per day starting on day 29 after transplantation.
The researchers initiated voriconazole on day 35. Four flavored ice pops from the same batch were tested and found positive for galactomannan. After discontinuation of these ice pops, levels returned to negative within seven days, and voriconazole therapy was discontinued on day 53. Thirty-seven ice pops from three marketed brands were tested for galactomannan; three of the cultures were found to contain penicillin, most likely due to contamination of the wrapping. In all samples, regardless of brand or flavor, high levels of galactomannan were observed. The source of galactomannan in the ice pops was undetermined, but food additives were suspected, included sodium gluconate, which is currently used as a stabilizer and thickener and is known to cause false-positive tests for galactomannan.
"Physicians should be aware of this unusual cause of interaction with the galactomannan test, which can result in unnecessary investigations and treatments," the authors write.
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