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Test ID: PBALP Porphobilinogen and Aminolevulinic Acid, Plasma

Shipping Instructions

Ship specimens refrigerated or frozen and in amber vial to protect from light.

Necessary Information

Include a list of medications the patient is currently taking.

Specimen Required

Patient Preparation: Patient should abstain from alcohol for at least 24 hours prior to specimen collection.

Supplies: Amber Frosted Tube, 5mL (T915)

Collection Container/Tube:

Preferred: Green top (sodium heparin)

Acceptable: Green top (lithium heparin), lavender top (EDTA), yellow top (ACD A or B)

Submission Container/Tube: Amber vial

Specimen Volume: 1 mL

Collection Instructions:

1. It is recommended that specimen collection occur during the acute phase. Porphobilinogen and aminolevulinic acid may be normal when the patient is not exhibiting symptoms.

2. Centrifuge and aliquot plasma into plastic vial.

Useful For

An equivalent option to urine for first-line test for evaluation of a suspected acute porphyria


Monitoring patients undergoing treatment for an acute intermittent porphyria or other acute porphyria

Method Name

Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)

Reporting Name

PBG and ALA, P

Specimen Type


Specimen Minimum Volume

0.3 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Plasma Frozen (preferred) 21 days LIGHT PROTECTED
  Refrigerated  7 days LIGHT PROTECTED

Clinical Information

The porphyrias are a group of inherited disorders resulting from enzyme defects in the heme biosynthetic pathway. Depending on the specific enzyme involved, various porphyrins and their precursors accumulate in different specimen types. The patterns of porphyrin accumulation in erythrocytes and plasma and the excretion of the heme precursors in urine and feces allow for the detection and differentiation of the porphyrias.


The porphyrias are typically classified as erythropoietic or hepatic based upon the primary site of the enzyme defect. In addition, of the 5 hepatic porphyrias, 4 typically present with acute neurological manifestations and are designated the acute porphyrias. Clinically, however, these attacks can be prolonged and chronic.


Three primary acute hepatic porphyrias: acute intermittent porphyria (AIP), hereditary coproporphyria (HCP), and variegate porphyria (VP), are associated with neurovisceral symptoms that typically onset during puberty or later. Common symptoms include severe abdominal pain, peripheral neuropathy, and psychiatric symptoms. A broad range of medications (including barbiturates and sulfa drugs), alcohol, infection, starvation, heavy metals, and hormonal changes may precipitate crises. Photosensitivity is not associated with AIP but may be present in HCP and VP.


Plasma porphobilinogen (PBG) and aminolevulinic acid (ALA) are elevated during the acute phase of these neurologic porphyrias. Urine and fecal porphyrin analysis should be performed to confirm the diagnosis and to distinguish among AIP, HCP, and VP. A biochemical diagnosis of AIP can be confirmed by measurement of PBG deaminase activity (PBGD_ / Porphobilinogen Deaminase, Whole Blood). VP and HCP can be confirmed by measurement of fecal porphyrins (FQPPS / Porphyrins, Feces). Once the biochemical diagnosis of an acute porphyria is established, molecular genetic testing is available (APGP / Acute Porphyria Gene Panel, Varies), which allows for diagnosis of at-risk family members.


The very rare (<10 cases described) autosomal recessive ALA dehydratase deficiency porphyria (ADP) is also a primary acute porphyria causing neurovisceral symptoms with variable age of onset. Biochemically, ADP is characterized by an isolated significant elevation of ALA. More commonly, however, isolated elevations of ALA are due to secondary inhibition of ALA dehydratase with acute lead intoxication, which results in the highest degree of aminolevulinic aciduria. Less significant elevations are seen in chronic lead intoxication,  tyrosinemia type I, alcoholism, and pregnancy.

The workup of patients with a suspected porphyria is most effective when following a stepwise approach.


For more information, see the following or call 800-533-1710 to discuss testing strategies:

-The Heme Biosynthetic Pathway 

-Porphyria (Acute) Testing Algorithm

-Porphyria (Cutaneous) Testing Algorithm

Reference Values

Porphobilinogen: ≤0.5 nmol/mL

Aminolevulinic Acid: ≤0.5 nmol/mL


Abnormal results are reported with a detailed interpretation that may include an overview of the results and their significance, a correlation to available clinical information provided with the specimen, differential diagnosis, recommendations for additional testing when indicated and available, and a phone number to reach one of the laboratory directors in case the referring physician has additional questions.

Day(s) Performed


Report Available

3 to 9 days

Test Classification

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information



LOINC Code Information

Test ID Test Order Name Order LOINC Value
PBALP PBG and ALA, P 96911-3


Result ID Test Result Name Result LOINC Value
38029 Porphobilinogen, P 17474-8
38028 Aminolevulinic Acid, P 79646-6
38030 Interpretation (PBALP) 59462-2
38031 Reviewed By 18771-6

Clinical Reference

1.Tortorelli S, White A, Raymond K: Disorders of porphyrin metabolism. In: Dietzen DJ, Bennett MJ, Wong ECC, Haymond S eds. Biochemical and Molecular Basis of Pediatric Disease. 5th ed. Academic Press; 2021:503-528

2. Anderson KE, Lobo R, Salazar D, et al: Biochemical diagnosis of acute hepatic porphyria: Updated expert recommendations for primary care physicians. Am J Med Sci. 2021 Aug;362(2):113-121. doi: 10.1016/j.amjms.2021.03.004

Mayo Clinic Laboratories | Genetics and Pharmacogenomics Catalog Additional Information: