PORPHOBILINOGEN DEAMINASE, ERYTHROCYTE
- PORPHOBILINOGEN DEAMINASE, ERYTHROCYTE
- Start Date
- Expiration Date
- CPT Codes
- Reference Test
- ATLAS Test Code
Lavender, EDTA Whole Blood
- Transport Info
Do not centrifuge
Do not remove plasma from cells
- Fasting Required?
- Patient Instructions
- Reference Range
Adult: 2.10-4.30 mU/g Hb
Porphobilinogen (PBG) deaminase (hydroxymethylbilane synthase or uroporphyrinogen I synthase) is expressed in units of mU per gram hemoglobin at 37°C. In persons genetically susceptible to acute intermittent porphyria (AIP), PBG deaminase concentrations are approximately half of reference values. Normal concentrations of erythrocyte PBG deaminase may include abnormal forms of hepatic PBG deaminase.
This test is most useful for family studies to determine which family members are at risk for acute intermittent porphyria. It is best performed in association with a specimen from the proband. Because of ambiguous results, this test is not generally recommended for diagnosis of individuals.
Porphobilinogen (PBG) deaminase (also called uroporphyrinogen I synthase or hydroxymethylbilane synthase) catalyzes the formation of hydroxymethylbilane from porphobilinogen. In persons genetically susceptible to acute intermittent porphyria (AIP), PBG deaminase levels are approximately half of usual values. Normal concentrations of erythrocyte PBG deaminase, however, may include rare abnormal forms of hepatic PBG deaminase. Since reticulocytes contain higher amounts of this enzyme, hemolytic processes cause an increase in the measured activity. Measurement of porphobilinogen deaminase activity is of limited use in assessing patients with latent acute intermittent porphyria. High urinary excretion of aminolevulinic acid and porphobilinogen are found in overt clinical disease, but these findings are absent in the latent form. PBG deaminase may show decreased activity in gene carriers without overt disease. The recommended approach to the diagnosis of the "acute porphyrias" (e.g., acute intermittent porphyria, hereditary coproporphyria, and variegate porphyria) is to measure urinary PBG. The clinical usefulness of PBG deaminase is limited. This test is most useful for family studies to determine which family members are at risk for acute intermittent porphyria. It is best performed in association with a specimen from the proband. Because of ambiguous results, this test is not generally recommended for studies on an individual.