Ordering Recommendation

Use to confirm a diagnosis of acute intermittent porphyria (AIP) following a positive urine porphobilinogen (PBG) test. Use to evaluate disease risk in family members of an individual with a confirmed diagnosis of AIP.

New York DOH Approval Status

This test is New York state approved.

Specimen Required

Patient Preparation

Perform automated hemoglobin on EDTA whole blood before preparing for transport.


Lavender (EDTA) or pink (K2EDTA).

Specimen Preparation

Transport 3 mL whole blood. (Min: 1 mL)

Storage/Transport Temperature


Unacceptable Conditions

Body fluid other than EDTA preserved whole blood. Clotted specimens.


Automated hemoglobin result must be included with specimen.


Ambient: 4 hours; Refrigerated: 1 week; Frozen: 1 month


Quantitative Enzymatic Assay/Fluorometry


Tue, Thu


1-6 days

Reference Interval

Adult: 2.10-4.30 mU/g Hb

Interpretive Data

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.

Compliance Category



This test is most useful for family studies to determine which family members are at risk for acute intermittent porphyria and is best performed in association with a specimen from the proband. Because of ambiguous results, this test is not generally recommended for diagnosis.

Hotline History


CPT Codes



Component Test Code* Component Chart Name LOINC
0099550 Porphobilinogen Deaminase RBC 49228-0
2011401 Hemoglobin (client supplied) 718-7
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.


  • Acute Intermittent Porphyria Enzyme
  • HMB Synthase
  • HMBS
  • Hydroxymethylbilane Synthase
  • PBG-D
  • Porphyria Enzyme
  • Uroporphyrinogen I Synthase
  • Uroporphyrinogen Synthase
Porphobilinogen (PBG) Deaminase, Erythrocyte