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Test ID: PTP Porphyrins, Total, Plasma

Reporting Name

Porphyrins, Total, P

Useful For

Monitoring treatment of patients with porphyria cutanea tarda

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
PFP Porphyrins, Fractionation, P No No

Testing Algorithm

If total porphyrins are >1.0 mcg/dL, then PFP / Porphyrins, Fractionation, Plasma will be performed at an additional charge.

 

The following algorithms are available in Special Instructions:

-Porphyria (Acute) Testing Algorithm

-Porphyria (Cutaneous) Testing Algorithm

Specimen Type

Plasma


Specimen Required


Collection Container/Tube:

Preferred: Green top (heparin)

Acceptable: Lavender top (EDTA)

Submission Container/Tube: Amber vial (T192)

Specimen Volume: 3 mL

Collection Instructions:

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

2. Centrifuge specimen and aliquot plasma into amber vial. Send plasma frozen.

3. Send specimen in amber vial to protect from light.

Additional Information: Include a list of medications the patient is currently taking.


Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time
Plasma Frozen 14 days

Reference Values

≤1.0 mcg/dL

Day(s) and Time(s) Performed

Monday through Friday; 8 a.m.

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 U.S. Food and Drug Administration.

CPT Code Information

84311-Porphyrins, total

82542-Porphyrins, fractionation (if appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
PTP Porphyrins, Total, P 2815-9

 

Result ID Test Result Name Result LOINC Value
8731 Porphyrins, Total, P 2815-9
34252 Reviewed By No LOINC Needed
33869 Interpretation 59462-2

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 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, hepatic porphyrias can be further classified as chronic or acute, based on their clinical presentation.

 

The 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.

 

Cutaneous photosensitivity is associated with the chronic hepatic porphyria, porphyria cutanea tarda (PCT), and the erythropoietic porphyrias including erythropoietic protoporphyria (EPP), X-linked dominant protoporphyria (XLDPP), and congenital erythropoietic porphyria (CEP). Although genetic in nature, environmental factors may exacerbate symptoms, significantly impacting the severity and course of disease.

 

CEP is an erythropoietic porphyria caused by uroporphyrinogen III synthase deficiency. Symptoms typically present in early infancy with red-brown staining of diapers, severe cutaneous photosensitivity with fluid-filled bullae and vesicles. Other common symptoms may include thickening of the skin, hypo- and hyperpigmentation, hypertrichosis, cutaneous scarring, and deformities of the fingers, eyelids, lips, nose, and ears. A few milder adult-onset cases have been documented as well as cases that are secondary to myeloid malignancies.

 

PCT is the most common form of porphyria and can be either sporadic (acquired) or inherited in an autosomal dominant manner. The most prominent clinical characteristics are cutaneous photosensitivity and scarring on sun-exposed surfaces. Patients experience chronic blistering lesions resulting from mild trauma to sun-exposed areas. These fluid-filled vesicles rupture easily, become crusted, and heal slowly. Secondary infections can cause areas of hypo- or hyperpigmentation or sclerodermatous changes and alopecia may develop at sites of repeated skin damage. Liver disease is common in patients with PCT as evidenced by abnormal liver function tests with 30% to 40% of patients developing cirrhosis. In addition, there is an increased risk of hepatocellular carcinoma.

 

Hepatoerythropoietic porphyria (HEP) occurs when an individual inherits PCT from both parents. Patients exhibit a similar clinical presentation to what is seen in CEP.

 

Clinical presentation of EPP and XLDPP is identical with onset of symptoms typically occurring in childhood. Cutaneous photosensitivity in sun-exposed areas of the skin generally worsens in the spring and summer months. Common symptoms may include itching, edema, erythema, stinging or burning sensations, and occasionally scarring of the skin in sun-exposed areas.

 

Plasma porphyrins are most appropriate for monitoring treatment of PCT. Although analysis in plasma is not recommended for diagnosis, increases in plasma porphyrin concentrations are observed in the cutaneous porphyrias and may be elevated during acute episodes of AIP, VP, and HCP. In addition, persons in chronic renal failure who develop bullous dermatosis similar to that associated with PCT may have increased plasma porphyrins.

 

The workup of patients with a suspected porphyria is most effective when following a stepwise approach. See Porphyria (Acute) Testing Algorithm and Porphyria (Cutaneous) Testing Algorithm in Special Instructions or contact Mayo Medical Laboratories to discuss testing strategies.

Interpretation

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.

Analytic Time

2 days (not reported Saturday or Sunday)

Clinical Reference

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. Anderson KE, Sassa S, Bishop DF, Desnick RJ: Disorders of Heme Biosynthesis: X-Linked Sideroblastic Anemia and the Porphyrias In The Online Metabolic and Molecular Bases of Inherited Disease. Edited by Valle D, Beaudet AL, Vogelstein B, et al. New York, McGraw-Hill, 2014. Accessed June 27, 2016. Available at http://ommbid.mhmedical.com/content.aspx?bookid=971&Sectionid=62638866

Method Name

PTP: Extraction and Scanning Spectrofluorometry

PFP: High-Performance Liquid Chromatography (HPLC)

Mayo Medical Laboratories | Genetics and Pharmacogenomics Catalog Additional Information:

mml-biochemical