ethylene glycol ingestion and Wood’s lamp-ing urine

21 Dec

NICE IDEA:
–most antifreeze (which contains ethylene glycol) has fluorescein added to it

–fluorescein should light up with a Wood’s lamp (=blacklight = UV)
–can you light up a patient’s face (to see if they drank some) and/or urine (to see if they’re peeing it out) to help your diagnosis?

NOT THAT USEFUL, SADLY:
STUDY 1: 60 docs in 2 groups; 150 urine specimens, all of which were fluorescent by flow cytometry
–Group 1 reported fluorescence in 80.7% of urine specimens
–group 2 reported fluorescence in 69.3%
–Interrater agreement was poor (72.5%)

STUDY 2: 2 docs, 27-30 urine specimens; shown sequentially or together on a test tube rack
–sequential: sensitivity 35%, specificity 75%, accuracy 48% for detecting florescein
–grouped:  sensitivity 42%, specificity 66%, accuracy 50%

BOTTOM LINE:
urine fluorescence for ethylene glycol ingestion, nice idea, not too clinically useful
not very sensitive, specific, or accurate
–we suck at eyeballing fluorescence, apparently
–stick with anion/osmol gaps, clinical judgement, etc.

Reference(s): study 1, study 2, another study that agrees, picture

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