Test ID: PBGU
Porphobilinogen, Quantitative, Random, Urine
Secondary ID 
A test code used for billing and in test definitions created prior to November 2011
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
First-line test for establishing a tentative diagnosis for acute neuropathic porphyria including acute intermittent porphyria, hereditary coproporphyria, and variegate porphyria.
Testing Algorithm Delineates situation(s) when tests are added to the initial order. This includes reflex and additional tests.
The following algorithms are available in Special Instructions:
-Porphyria (Acute) Testing Algorithm
-Porphyria (Cutaneous) Testing Algorithm
Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test
Method Name A short description of the method used to perform the test
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) Stable Isotope Dilution Analysis
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
AIP (Acute Intermittent Porphyria)
HCP (Hereditary Coproporphyria)
Hereditary Coproporphyria (HCP)
PBG (Porphobilinogen)
Porphobilinogen (PBG)
Variegate Porphyria (VP)
VP (Variegate Porphyria)
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Container/Tube: Amber, 60-mL urine bottle (Supply T596)
Specimen Volume: 20 mL
Collection Instructions:
1. Collect a random urine specimen.
2. No preservative necessary but pH must be >5.0.
3. Protect specimen from light.
Forms:
1. 1. New York Clients-Informed consent is required. Please document on the request form or electronic order that a copy is on file. An Informed Consent for Genetic Testing (Supply T576) is available in Special Instructions.
2. 2. If not ordering electronically, submit a Biochemical Genetics Request Form (Supply T439) with the specimen.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | NA |
| Lipemia | NA |
| Icterus | NA |
| Other | NA |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Urine | Frozen (preferred) | 7 days |
| Refrigerated | 7 days |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Urinary porphobilinogen (PBG) is elevated during the acute phase of the neurologic porphyrias: acute intermittent porphyria (AIP), hereditary coproporphyria (HCP), and variegate porphyria (VP). Acute attacks may produce symptoms of cerebral dysfunction and damage (confusion, "psychiatric disease"), autonomic neuropathy, constipation, urinary retention, tachycardia, hypertension, and severe (sometimes chronic) abdominal pain. In the acute phase, these disorders can be life threatening. Between attacks patients have mild symptoms that may include psychoneuroses. Several studies indicate that approximately 1 in 300 psychiatric patients have AIP.
The common symptoms of AIP, HCP, and VP mimic many other diseases from acute appendicitis to acute schizophrenia. Acute episodes usually begin with or include abdominal discomfort ranging from mild cramping to severe pain that suggests a need for surgical intervention. These symptoms and outward signs are common to a variety of medical problems and diagnosis usually depends on timely, accurate laboratory testing. Frequently, surgical intervention can be avoided if the laboratory returns an elevated level for urinary PBG. For additional information on the recommended order of testing, see Porphyria (Acute) Testing Algorithm and Porphyria (Cutaneous) Testing Algorithm in Special Instructions. Refer to The Challenges of Testing For and Diagnosing Porphyrias, Mayo Medical Laboratories Communique 2002 Nov;27(11) for more information regarding diagnostic strategy.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
< or =1.3 mcmol/L
Interpretation Provides information to assist in interpretation of the test results
Abnormal results are reported with a detailed interpretation including an overview of the results and their significance, a correlation to available clinical information provided with the specimen, differential diagnosis, and 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.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Ideally, specimen collection should occur during the acute phase. Porphobilinogen (PBG) may be normal when the patient is not exhibiting symptoms.
PBG is susceptible to degradation at high temperatures, at pH <5.0, and on prolonged exposure to light. Specimens should be frozen immediately following collection and protected from light.
Urine and fecal porphyrin analysis should be performed to confirm the diagnosis and to distinguish between acute intermittent porphyria (AIP), hereditary coproporphyria (HCP), and variegate porphyria (VP). A biochemical diagnosis of AIP can be confirmed by measurement of PBG deaminase activity (PBGD_/88925 Porphobilinogen [PBG] Deaminase, Whole Blood). VP and HCP can be confirmed by measurement of fecal porphyrins (FQPPS/81652 Porphyrins, Feces).
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Tortorelli S, Kloke K, Raymond K: Chapter 15: Disorders of porphyrin metabolism. In Biochemical and Molecular Basis of Pediatric Disease. Fourth edition. Edited by DJ Dietzen, MJ Bennett, ECC Wong. AACC Press, 2010, pp 307-324
2. Nuttall KL, Klee GG: Analytes of hemoglobin metabolism - porphyrins, iron, and bilirubin. In Tietz Textbook of Clinical Chemistry. Fifth edition. Edited by CA Burtis, ER Ashwood. Philadelphia, WB Saunders Company, 2001, pp 584-607
3. Anderson KE, Sassa S, Bishop DF, Desnick RJ: Disorders of heme biosynthesis: X-linked sideroblastic anemia and the porphyrias. In The Metabolic Basis of Inherited Disease. Eighth edition. Edited by CR Scriver, AL Beaudet, WS Sly, et al. New York, McGraw-Hill BookCompany, 2001, pp 2991-3062
Method Description Describes how the test is performed and provides a method-specific reference
Porphobilinogen (PBG) in urine is quantified by liquid chromatography tandem-mass spectrometry analysis in positive ion mode. An internal standard (13C2-PBG) is added to 1 mL of acidified urine. PBG and 13C2-PBG are extracted from the sample using an Oasis HLB column on a Gilson ASPEC Workstation. Separation of PBG from the specimen matrix is achieved by a reverse phase HPLC. PBG and the internal standard are monitored through their corresponding precursor and product ion pairs. The ion pair for PBG and 13C2-PBG are m/z 227 to m/z 210 and m/z 229 to m/z 212, respectively.(Ford RE, Magera MJ, Kloke KM, et al: Quantitative measurement of porphobilinogen in urine by stable-isotope dilution liquid chromatography-tandem mass spectrometry. Clin Chem 2001 September;47[9]:1627-1632)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Friday; 8 a.m.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
84110
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| 29365 | Porphobilinogen, U | 2811-8 |
| 29366 | Interpretation (PBGU) | 59462-2 |
| 35032 | Reviewed By | 2811-8 |
External
link
PDF
document
Excel
document
Word
document