Diagnosis; Screening

Establish or confirm diagnosis

Preferred test to begin assessment for congenital erythropoietic porphyria and porphyria cutanea tarda and during symptomatic periods for acute intermittent porphyria, hereditary coproporphyria, and variegate porphyria when specimen transport will not exceed 72 hours.

Is research allowed on the sample after clinical testing is complete? Help
N/A

An aliquot of urine is acidified and mesoporphyrin is added as an injection marker. Porphyrins in the acidified urine are separated by HPLC and the eluted porphyrins are quantified by comparison of their fluorescence intensity to that of known porphyrin standards. Porphobilinogen (PBG) in urine is quantified by liquid chromatography-tandem … An aliquot of urine is acidified and mesoporphyrin is added as an injection marker. Porphyrins in the acidified urine are separated by HPLC and the eluted porphyrins are quantified by comparison of their fluorescence intensity to that of known porphyrin standards. Porphobilinogen (PBG) in urine is quantified by liquid chromatography-tandem mass spectrometry after addition of stable isotope-labeled PBG internal standard and solid-phase extraction. View more

Tests performed
Entire test performed in-house

Accuracy was assessed by the analysis of proficiency testing specimens and was acceptable. Intra assay precision was performed at 3 levels: CV results ranged from 0% to 13.2% (N=10 each). Inter assay precision was performed at 3 levels: CV results ranged from 0% to 29.1%(N=10 each). The analytical measurement range … Accuracy was assessed by the analysis of proficiency testing specimens and was acceptable. Intra assay precision was performed at 3 levels: CV results ranged from 0% to 13.2% (N=10 each). Inter assay precision was performed at 3 levels: CV results ranged from 0% to 29.1%(N=10 each). The analytical measurement range is analyte dependent and ranges from 0 – 200 µg/dL. View more

Porphobilinogen (PBG) and porphyrins are susceptible to degradation at high temperature, at pH below 5.0, and exposure to light. Neither erythropoietic protoporphyria nor X-linked dominant protoporphyria are detected utilizing urine porphyrins and PBG measurements. Ethanol and a variety of medications are known to interfere with heme synthesis leading to elevations … Porphobilinogen (PBG) and porphyrins are susceptible to degradation at high temperature, at pH below 5.0, and exposure to light. Neither erythropoietic protoporphyria nor X-linked dominant protoporphyria are detected utilizing urine porphyrins and PBG measurements. Ethanol and a variety of medications are known to interfere with heme synthesis leading to elevations in urine porphyrins, particularly coproporphyrin. Coproporphyrin elevation without concomitant PBG elevation should not be used as the basis for the diagnosis of porphyria but may warrant follow-up testing with fecal porphyrin analysis. View more

Is proficiency testing performed for this test? Help
Yes

Method used for proficiency testing: Help
Formal PT program

PT Provider: Help
College of American Pathologists, CAP

Description of PT method: Help
Formal PT program.

Description of internal test validation method: Help
This test was laboratory developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements.

Software used to interpret novel variations Help
N/A

Laboratory's policy on reporting novel variations Help
N/A