Porphyria

Tests

Measurement of porphyrins and porphyrin precursors in blood, urine and faeces are the main tests for assessing patients with symptoms that may be caused by porphyria. Measurement of enzyme activities in cells and DNA testing for mutations are most useful for assessing people who may be affected but do not currently have symptoms and close relatives of affected persons.

• Measurement of porphobilinogen or PBG in urine is the most important test for diagnosing an acute neurological porphyria.
• Measurement of porphyrins in urine, faeces, red blood cells and blood plasma are used to differentiate the various types of porphyrias that may have the same symptoms.
• Measurement of enzyme activity in red blood cells may be used to identify relatives of persons with AIP who also are potentially affected.
• Identification of specific mutations in genes (DNA testing) may also be used to identify potentially affected persons but is difficult, expensive and rarely available outside research laboratories at present.