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| A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # |
URINE PORPHYRIN SCREEN
MessageTest Code
Preferred Specimen
Minimum Volume
Limitations
Drugs such as methyl red, pyridium, urosein, and melanogen will cause false positives.
This fluorescense method will not distinguish between uroporphyrin, coproporphyrin, and protoporphyrin but it will rule out porphobilinogen and aminolevulinic acid. The identification of the specific porphyrins requires additional extraction techniques and the analysis of fecal and erythrocyte samples.
Clinical Significance
Porphyrins are the intermediate compounds in the production of heme. Fluorescent screening for uroporphyrin, coproporphyrin, and protoporphyrin requires their extraction into a mixture of glacial acetic acid and ethyl acetate. The solvent layer is then examined under a Wood’s lamp. Porphobilinogen, delta aminolevulinic acid, and the porphyrinogens are not detected by this method.
An in-house screening method is necessary to avoid inappropriate and expensive testing for specific porphryins in urine when porphyria is a clinical consideration.
