The urine of a patient who has ingested antifreeze may fluoresce if sodium fluorescein has been added by the manufacturer.
Features:
(1) A patient presents with suspected ethylene glycol intoxication.
(2) A urine sample is examined under a fluorescent light with the proper wavelength.
(3) If the urine fluoresces then ethylene glycol poisoning should be suspected.
Theelen notes that emission spectrum of fluorescein peaks at 540 nm with a green color. A Wood’s lamp (wavelength 365 nm) is too low and may be more likely to detect fluorophores other than fluorescein.
False positives:
(1) porphyria
(2) drugs, food additives or other chemicals in the urine that fluoresce (fluorophores)
(3) Pseudomonas aeruginosa urinary tract infection or contamination of the urine sample
False negatives:
(1) The antifreeze was formulated without sodium fluorescein as an additive.
(2) The urine is collected more than more than 4 hours since the ingestion.
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