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Test ID: FQPPS Porphyrins, Feces

Reporting Name

Porphyrins, F

Useful For

Evaluation of patients who present with signs or symptoms suggestive of porphyria cutanea tarda, hereditary coproporphyria, variegate porphyria, congenital erythropoietic porphyria, erythropoietic protoporphyria, or X-linked dominant protoporphyria

Testing Algorithm

The following algorithms are available in Special Instructions:

-Porphyria (Acute) Testing Algorithm

-Porphyria (Cutaneous) Testing Algorithm

Specimen Type

Fecal


Specimen Required


Container/Tube: Stool container (T291)

Specimen Volume: Entire collection (48, 72, or 96 hour). 24-Hour collection is adequate if the collection volume is approximately 100 g.

Collection Instructions:

1. Patient should be instructed to refrain from red meat and aspirin-containing medications for 3 days prior to, as well as during, specimen collection. Compliance should be indicated.

2. No barium, laxatives, or enemas may be used within 24 hours of starting the collection.

Additional Information:

1. Length of collection period is required.

2. Specimens smaller than 100 g may not provide interpretable results.

3. Include a list of medications the patient is currently taking.


Specimen Minimum Volume

10 g

Specimen Stability Information

Specimen Type Temperature Time
Fecal Frozen (preferred) 14 days
  Refrigerated  14 days

Reference Values

UROPORPHYRIN I

<120 mcg/24 hours

 

UROPORPHYRIN III

<50 mcg/24 hours

 

HEPTACARBOXYL PORPHYRIN I

<40 mcg/24 hours

 

HEPTACARBOXYL PORPHYRIN III

<40 mcg/24 hours

 

ISOHEPTACARBOXYL PORPHYRINS

<30 mcg/24 hours

 

HEXACARBOXYL PORPHYRIN I

<10 mcg/24 hours

 

HEXACARBOXYL PORPHYRIN III

<10 mcg/24 hours

 

ISOHEXACARBOXYL PORPHYRINS

<10 mcg/24 hours

 

PENTACARBOXYL PORPHYRIN I

<20 mcg/24 hours

 

PENTACARBOXYL PORPHYRIN III

<20 mcg/24 hours

 

ISOPENTACARBOXYL PORPHYRINS

<80 mcg/24 hours

 

COPROPORPHYRIN I

<500 mcg/24 hours

 

COPROPORPHYRIN III

<400 mcg/24 hours

 

ISOCOPROPORPHYRIN

<200 mcg/24 hours

 

PROTOPORPHYRINS

<1,500 mcg/24 hours

 

COPROPORPHYRIN III/COPROPORPHYRIN I RATIO

<1:20

 

See The Heme Biosynthetic Pathway in Special Instructions.

Day(s) and Time(s) Performed

Monday through Friday; 1 p.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

84126

LOINC Code Information

Test ID Test Order Name Order LOINC Value
FQPPS Porphyrins, F In Process

 

Result ID Test Result Name Result LOINC Value
W6 Total weight 30078-0
TM70 Collection Duration 13363-7
15517 Uroporphyrin I 26691-6
15518 Uroporphyrin III 33585-1
15519 Heptacarboxyl I 49900-4
15520 Heptacarboxyl III 49901-2
15521 Isoheptacarboxyl 23885-7
15522 Hexacarboxyl I 23874-1
15523 Hexacarboxyl III 23875-8
15524 Isohexacarboxyl 23886-5
15525 Pentacarboxyl I 33623-0
15526 Pentacarboxyl III 33624-8
15527 Isopentacarboxyl 23887-3
15528 Coproporphyrin I 23845-1
15529 Coproporphyrin III 23846-9
15530 Isocoproporphyrin 33625-5
15534 Protoporphyrin 2891-0
15545 CoproIII/CoproI ratio 33618-0
81652 Interpretation (FQPPS) 59462-2
35013 Reviewed By No LOINC Needed

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, which typically onset during puberty or later. Common symptoms include severe abdominal pain, peripheral neuropathy, and psychiatric symptoms. Crises may be precipitated by a broad range of medications (including barbiturates and sulfa drugs), alcohol, infection, starvation, heavy metals, and hormonal changes. Photosensitivity is not associated with AIP, but may be present in HCP and VP.

 

Cutaneous photosensitivity is associated with the chronic hepatic porphyrias: porphyria cutanea tarda (PCT) and the erythropoietic porphyrias; 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 is most commonly sporadic (acquired), but in about 25% of cases it is 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 may result in the development of alopecia at sites of repeated skin damage. Liver disease is common in patients with PCT as evidenced by abnormal liver function tests and 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.

 

Increased fecal porphyrin excretions are observed most commonly in symptomatic patients with CEP, PCT, HCP, and VP. In quiescent phases, as well as prior to puberty, fecal porphyrin excretion may be within normal limits. Patients with AIP may have elevated fecal porphyrin levels during severe attacks. EPP and XLDPP patients may have elevated protoporphyrin levels, however, these disorders cannot be diagnosed by fecal analysis alone.

 

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.

Clinical Reference

1. Tortorelli S, Kloke KM, Raymond KM: 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: X-Linked sideroblastic anemia and the porphyrias. In Disorders of Heme Biosynthesis. Edited by D Valle, AL Beaudet, B Vogelstein, et al. New York: McGraw-Hill; 2014. Accessed June 27, 2016. Available at http://ommbid.mhmedical.com/content.aspx?bookid=971&Sectionid=62638866

Analytic Time

4 days (not reported on Saturday or Sunday)

Method Name

High-Performance Liquid Chromatography (HPLC)

Porphyrins are quantified by fluorescence.

Forms

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 (T576) is available in Special Instructions.

Mayo Medical Laboratories | Genetics and Pharmacogenomics Catalog Additional Information:

mml-biochemical