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Epic Test Code LAB21001 Porphyrins, Feces

Additional Codes

MML Code: FQPPS

LIS Code: PYST

NY State Approved

Yes

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Reporting Name

Porphyrins, F

Method Name

High-Performance Liquid Chromatography (HPLC)

Specimen Stability Information

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


Necessary Information


1. Weight of the non-homogenized sample

2. Collection duration

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

4. Indicate if patient was compliant with the patient preparation requirements.



Specimen Required


Patient Preparation:

1. For 3 days before collection and during the entire specimen collection period, patient must refrain from eating red meat and or taking any aspirin-containing medications.

2. Patient should not use barium, laxatives, or enemas for 24 hours before starting, as well as during, specimen collection.

Collection Container/Tube: Stool Containers - 24, 48, 72 Hour Kit (T291). No preservative.

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

Collection Instructions:

1. Collect all stool specimens within a 24, 48, 72, or 96 hour timeframe.

2. Do not add preservative.

3. Send entire collection.

Additional Information:

1. Length of collection period is required.

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

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


Specimen Type

Fecal

Specimen Minimum Volume

See Specimen Required

Reference Values

UroporphyrinI:

<120 mcg/24 h

 

Uroporphyrin III:

<50 mcg/24 h

 

Heptacarboxyl porphyrin I:

<40 mcg/24 h

 

Heptacarboxyl porphyrin III:

<40 mcg/24 hours

 

Isoheptacarboxyl porphyrins:

<30 mcg/24 h

 

Hexacarboxnyl porphyrin:

<10 mcg/24 h

 

Hexacarboxnyl porphyrin III:

<10 mcg/24 h

 

Isohexacarboxnyl porphyrins :

<10 mcg/24 h

 

Pentacarboxyl porphyrin I:

<20 mcg/24 hours

 

Pentacarboxyl porphyrin II:

<20 mcg/24 h

 

Isopentacarboxyl porphyrins:

<80 mcg/24 hours

 

Coproporphyrin I:

<500 mcg/24 h

 

Coproporphyrin III:

<400 mcg/24 h

 

Isocoproporphyrin:

<200 mcg/24 h

 

Protoporphyrins:

<1,500 mcg/24 h

 

Coproporphyrin III/Coproporphyrin I RATIO:

<1.20

 

See The Heme Biosynthetic Pathway

Report Available

3 to 6 days

Day(s) Performed

Monday, Thursday

CPT Code Information

84126

Reject Due To

Specimens in preservative Reject
 

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:

-Porphyria (Acute) Testing Algorithm

-Porphyria (Cutaneous) Testing Algorithm

Disease States

  • Porphyria

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. For more information see The Heme Biosynthetic Pathway.

 

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 caused by hepatic inhibition of the enzyme uroporphyrinogen decarboxylase (UROD). It is most often sporadic (acquired), but in about 20% of cases, a heterozygous variant in UROD increases the susceptibility to disease. 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) is a rare autosomal recessive form of porphyria caused by homozygous or compound heterozygous variants in UROD. It typically presents in early childhood with both erythropoietic and cutaneous manifestations and is similar 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 or call 800-533-1710 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.

Cautions

Heme from red meat can contribute to fecal protoporphyrin concentrations and cause a misleading indication of erythropoietic protoporphyria, X-linked dominant protoporphyria, or variegate porphyria.

 

Aspirin ingestion may cause minimal gastrointestinal bleeding, leading to false elevations of protoporphyrin.

 

Specimen submitted should contain at least 100 g of feces. Specimens smaller than 100 g may not provide interpretable results. Specimens weighing less than 10 grams will be rejected.

Specimen Retention Time

1 week