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Porphyrias are a group of eight inherited or acquired enzyme disorders of the heme biosynthetic pathway that result in overproduction of porphyrins or porphyrin precursor compounds. Clinical symptoms include abdominal pain, and neurologic disorders, bullous skin lesions, and photosensitivity.
Tests generally appear in the order most useful for common clinical situations
| Test name: Porphobilinogen (PBG), Urine |
| ARUP #: 0080260 |
| Methodology: Quantitative Ion Exchange Chromatography/Spectrophotometry |
| Use: Essential first-line test during suspected attack of acute porphyria Use in determining metabolic response to IV hematin |
| Limitations: 24-hour specimen is more sensitive |
| Follow-up: If result is negative, but high clinical suspicion exists, repeat when symptoms are present |
| Test name: Porphyrins, Fractionation & Quantitation, Urine |
| ARUP #: 2002058 |
| Methodology: Quantitative High Performance Liquid Chromatography |
| Use: Evaluate cutaneous photosensitivity to exclude or include PCT, CEP or HEP |
| Limitations: 24-hour specimen is more sensitive Coproporphyrinuria is non-specific Urine coproporphyrin is elevated in many common disorders |
| Follow-up: If test is negative, but high clinical suspicion still exists, repeat when symptoms are present |
| Test name: Porphyrins & Porphobilinogen (PBG), Urine |
| ARUP #: 2002181 |
| Methodology: Quantitative High Performance Liquid Chromatography/Quantitative Ion Exchange Chromatography/Quantitative Spectrophotometry |
| Use: Evaluate patients with suspected porphyria presenting with cutaneous and/or neurologic and psychiatric symptoms |
| Limitations: 24-hour specimen is more sensitive |
| Test name: Porphyrins, Fecal |
| ARUP #: 0099824 |
| Methodology: Quantitative High Performance Liquid Chromatography |
| Use: Distinguish among AIP, HCP, HEP, VP |
| Limitations: Bacterial modification of fecal porphyrins is extensive Meat in diet may influence test results |
| Test name: Porphyrins, Serum Total |
| ARUP #: 0080429 |
| Methodology: Quantitative Scanning Fluorometry |
| Use: Monitor PCT Confirm VP and EPP Former initial test for cutaneous porphyrias |
| Limitations: Does not differentiate specific porphyrin present |
| Test name: Aminolevulinic Acid (ALA), Urine |
| ARUP #: 0080103 |
| Methodology: Quantitative Ion Exchange Chromatography/Spectrophotometry |
| Use: Evaluate suspected ADP or other acute porphyria, lead poisoning or hereditary tyrosinemia |
| Limitations: 24-hour specimen is more sensitive |
| Follow-up: If lead poisoning suspected, order whole blood lead testing |
| Test name: Porphobilinogen (PBG) Deaminase, Erythrocyte |
| ARUP #: 0099550 |
| Methodology: Quantitative Enzymatic/Fluorometry |
| Use: Useful in family studies to determine which members are most at risk for AIP PBG deaminase more correctly termed hydroxymethylbilane synthase |
| Limitations: Not recommended for diagnosis of an individual patient Best performed in association with a specimen from an unaffected family member |
| Test name: Zinc Protoporphyrin (ZPP), Whole Blood |
| ARUP #: 0020605 |
| Methodology: Quantitative Hematofluorometry |
| Use: Screen for EPP Confirm ADP |
| Limitations: Also elevated in early and late iron deficiency, anemia of chronic disease, and chronic lead poisoning Less specific than EP test |
| Follow-up: Order whole blood lead testing to evaluate for lead poisoning If ZPP is elevated, order EP and/or serum porphyrins |
| Test name: Erythrocyte Porphyrin (EP), Whole Blood |
| ARUP #: 0020610 |
| Methodology: Quantitative Extraction/Fluorometry |
| Use: Evaluate the presence of EPP |
| Limitations: Also elevated in early and late iron deficiency, anemia of chronic disease, and chronic lead poisoning |
| Follow-up: Order whole blood lead testing to evaluate for lead poisoning |
| Test name: Cutaneous Direct Immunofluorescence, Biopsy |
| ARUP #: 0092572 |
| Methodology: Direct Immunofluorescence (Direct Fluorescent Antibody Stain) |
| Use: Biopsy of skin for unusual cutaneous presentations |
| Limitations: Characteristic pattern of staining but not specific |
| Test name: Epithelial Skin Antibody |
| ARUP #: 0090299 |
| Methodology: Indirect Immunofluorescence (Indirect Fluorescent Antibody) |
| Use: Serum testing for epithelial antibodies |
| Limitations: Negative in porphyria and pseudoporphyria, positive in immunobullous diseases |
