Porphyrins Evaluation, Whole Blood
Method Description Describes how the test is performed and provides a method-specific reference
This evaluation is performed as a 3-step analysis. First, the total RBC porphyrin concentration is determined by extracting the porphyrins from washed, resuspended RBCs using a mixture of ethyl acetate and acetic acid. The porphyrins are then back extracted into dilute hydrochloric acid. Total porphyrins are quantified using this extract via spectrofluorometry.(Piomelli S: Free erythrocyte porphyrins in the detection of undue absorption of Pb and Fe deficiency. Clin Chem 1977;23:264-269)
If the total porphyrin concentration is elevated, the RBCs are re-extracted using an acetone:water solution. This extraction allows for separation and quantification of zinc-complexed and noncomplexed (free) protoporphyrin via HPLC.(Ford RE, Ellefson RD: Quantitation of erythrocyte protoporphyrins and zinc protoporphyrin by high-pressure liquid chromatography. Clin Chem 1984;30:972)
Depending on the results from the acetone:water extraction, the original acid extract may be submitted for HPLC analysis to separate and quantitate the individual porphyrin analytes to aid in the diagnosis of congenital erythropoietic porphyria.(Ford RE, Ou C, Ellefson RD: Liquid chromatographic analysis for urinary porphyrins. Clin Chem 1981;27:397-401)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Friday; 8 a.m.