Correspondence

Urine Fluorescence in Ethylene Glycol Poisoning

N Engl J Med 2007; 356:2006-2007May 10, 2007

Article

To the Editor:

With regard to the Image in Clinical Medicine by McStay and Gordon (Feb. 8 issue),1 the presence of urine fluorescence can be short lived, less than 4 hours from the time of ingestion.2 This brief duration poses the potential for false negative results. Not all brands of antifreeze contain fluorescein as a colorant for the detection of radiator leaks. Other researchers have reported that urine specimens from children may fluoresce without an exposure to antifreeze.3,4 A database lists 148 substances, including a number of drugs, food products, toxins, and endogenous compounds, that can contribute to urine fluorescence and the potential for false positive results.5 Urine fluorescence as an adjunctive tool in the evaluation of ethylene glycol ingestion may be helpful, but physicians should be aware of the considerable limitations of this test, including both false negative and false positive results.

Mark L. Winter, Ph.D.
Wayne R. Snodgrass, M.D., Ph.D.
University of Texas Medical Branch, Galveston, TX 77555-1175
mwinter@utmb.edu

5 References

1. 1

   McStay CM, Gordon PE. Urine fluorescence in ethylene glycol poisoning. N Engl J Med 2007;356:611-611
   Full Text | Web of Science | Medline

2. 2

   Winter ML, Ellis MD, Snodgrass WR. Urine fluorescence using a Wood's lamp to detect the antifreeze additive sodium fluorescein: a qualitative adjunctive test in suspected ethylene glycol ingestions. Ann Emerg Med 1990;19:663-667
   CrossRef | Web of Science | Medline

3. 3

   Casavant MJ, Shah MN, Battels R. Does the fluorescent urine indicate antifreeze ingestion by children? Pediatrics 2001;107:113-114
   CrossRef | Web of Science | Medline

4. 4

   Parsa T, Cunningham SJ, Wall SP, Almo SC, Crain EF. The usefulness of urine fluorescence for suspected antifreeze ingestion in children. Am J Emerg Med 2005;23:787-792[Erratum, Am J Emerg Med 2006;24:396.]
   CrossRef | Web of Science | Medline

5. 5

   Hazardous Substances Data Bank (HDSB) of the National Library of Medicine. (Accessed April 19, 2007, at http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?HSDB.)
   

To the Editor:

McStay and Gordon report on a patient with antifreeze (presumably ethylene glycol) intoxication. The urine of their patient showed blue fluorescence under ultraviolet excitation. Fluorescein is a chromophore with a high quantum yield of fluorescence. Therefore, assessment of urine fluorescence was suggested in cases of suspected ethylene glycol intoxication.1 The emission spectrum of fluorescein peaks at approximately 540 nm (green), and it is virtually absent below 500 nm (blue).2 Thus, the deep-blue urine fluorescence described by McStay and Gordon presumably originated from a fluorophore other than fluorescein. A number of unknown fluorophores may be assumed to be the source of the fluorescence observed. For instance, a strong blue fluorescence was observed after excitation with ultraviolet light for certain ion–chelate complexes.3 Only a strong green fluorescence points to fluorescein ingested with antifreeze. In a case of unusual fluorescence, as shown here, one should consider substances other than ethylene glycol as the source of intoxication.

Thomas Theelen, M.D., Ph.D.
Radboud University Nijmegen Medical Center, 6500 HB Nijmegen, the Netherlands

3 References

1. 1

   Winter ML, Ellis MD, Snodgrass WR. Urine fluorescence using a Wood's lamp to detect the antifreeze additive sodium fluorescein: a qualitative adjunctive test in suspected ethylene glycol ingestions. Ann Emerg Med 1990;19:663-667
   CrossRef | Web of Science | Medline

2. 2

   Du H, Fuh R-CA, Li J, Corkan LA, Lindsey JS. PhotochemCAD: a computer-aided design and research tool in photochemistry. Photochem Photobiol 1998;68:141-142
   Web of Science

3. 3

   Bekiari V, Lianos P. Strongly luminescent poly(ethylene glycol)-2,2-bipyridine lanthanide ion complexes. Adv Mater 1998;10:1455-1458
   CrossRef | Web of Science

Author/Editor Response

We agree with Winter and Snodgrass and strongly caution clinicians against making critical management decisions solely on the basis of urine fluorescence. This recommendation is especially pertinent in the pediatric population, given the extremely high rate of fluorescence in patients who have not been poisoned.1,2 Difficulties with positive and negative controls as well as interobserver variability are also important considerations. We acknowledge that the result of our own bedside test could represent a false positive finding from one or more fluorophores, as Theelen points out. In a report by Parsa et al., images of fluorescent urine samples from children who have not been poisoned retain their blue hue despite elevated levels of sodium fluorescein.2

Given the lack of rapidly available testing for ethylene glycol in many centers, we still believe that urine fluorescence may have some use as an adjuvant test in adults. Above all, we strongly urge clinicians with questions regarding testing and management of both suspected and confirmed poisonings to consult with their local poison-control center.

Christopher M. McStay, M.D.
Peter E. Gordon, M.D.
New York University, New York, NY 10016
mcstac01@med.nyu.edu

2 References

1. 1

   Casavant MJ, Shah MN, Battels R. Does the fluorescent urine indicate antifreeze ingestion by children? Pediatrics 2001;107:113-114
   CrossRef | Web of Science | Medline

2. 2

   Parsa T, Cunningham SJ, Wall SP, Almo SC, Crain EF. The usefulness of urine fluorescence for suspected antifreeze ingestion in children. Am J Emerg Med 2005;23:787-792[Erratum, Am J Emerg Med 2006;24:396.]
   CrossRef | Web of Science | Medline