Some chemicals have ring structures that absorb light, which can cause in vitro decomposition of the compound. This can result in a falsely low concentration when the specimen is analyzed.
Analytes affected:
(1) vitamin A
(2) vitamin B6
(3) bilirubin
(4) beta-carotene
(5) porphyrins
(6) urobilinogen
(7) tryptophan
(8) delta-aminolevulinic acid
(9) citrulline
(10) certain drugs with ring structures (methotrexate, etc)
Specimens may be affected if:
(1) left in sunlight
(2) exposed to a light source emitting at the appropriate wavelength.
Suitable transport and storage containers:
(1) aluminum foil
(2) amber container
(3) light-proof container
Differential diagnosis of false decrease in an analyte:
(1) failure to use an appropriate preservative
(2) bacterial contamination
(3) failure to store or transport the specimen at the proper temperature
(4) delayed transport
To read more or access our algorithms and calculators, please log in or register.
