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Test Code LAB433 Porphyrins, Quantitative, 24 Hour, Urine

Additional Codes

PQNU

Useful For

Preferred screening test for congenital erythropoietic porphyria and porphyria cutanea tarda and during symptomatic periods for acute intermittent porphyria, hereditary coproporphyria, and variegate porphyria when specimen transport will be longer than 72 hours

Testing Algorithm

The following algorithms are available:

-Porphyria (Acute) Testing Algorithm 

-Porphyria (Cutaneous) Testing Algorithm 

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Urine


Ordering Guidance


This 24-hour urine test should be ordered when the specimen will not reach Mayo Clinic Laboratories (MCL) within 72 hours. If the specimen will reach MCL within 72 hours, order PQNRU / Porphyrins, Quantitative, Random, Urine.



Shipping Instructions


Ship specimen in amber container to protect from light.



Necessary Information


1. 24-Hour volume (in milliliters) is required.

2. Patient's sex is required.

3. Collection date and time should be documented upon completion of the 24-hour collection.

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



Specimen Required


Patient Preparation: Patient should not consume any alcohol for the 24 hours before, as well as during, specimen collection.

Supplies:

-Urine Container - Amber, 60-mL (T596)

-Sodium Carbonate, 5 gram (T272)

Container/Tube: Amber, 60-mL urine container

Specimen Volume: 20 to 50 mL

Collection Instructions:

1. Add 5 g of sodium carbonate as preservative at start of collection. This preservative is intended to achieve a pH above 7. Do not substitute sodium bicarbonate for sodium carbonate.

2. Collect a 24-hour urine specimen.

3. The container should be refrigerated and protected from light as much as possible during collection.

4. Record volume and duration. An aliquot should be frozen when collection is complete.

Additional Information: See Urine Preservatives-Collection and Transportation for 24-Hour Urine Specimens for multiple collections.


Specimen Minimum Volume

15 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Urine Frozen 7 days LIGHT PROTECTED

Reference Values

Uroporphyrins (Octacarboxyl):

≤30 nmol/24 h

 

Heptacarboxylporphyrins:

≤9 nmol/24 h

 

Hexacarboxylporphyrins:

≤8 nmol/24 h

 

Pentacarboxyporphyrins:

≤10 nmol/24 h

 

Copropprphyrins (Tetracboxyl)

Males: ≤230 nmol/24 h

Females: ≤168 nmol/24 h

 

Porphobilinogen:

≤2.2 mcmol/24 h

Day(s) Performed

Monday through Friday

CPT Code Information

84110-Porphobilinogen, quantitative

84120-Porphyrins, quantitation and fractionation

LOINC Code Information

Test ID Test Order Name Order LOINC Value
PQNU Porphyrins, QN, U 43116-3

 

Result ID Test Result Name Result LOINC Value
TM3 Collection Duration 13362-9
VL1 Urine Volume 3167-4
29357 Uroporphyrin, Octa 15096-1
29358 Heptacarboxylporphyrins 25434-2
29359 Hexacarboxylporphyrins 25438-3
29360 Pentacarboxylporphyrins 25494-6
29361 Coproporphyrin, Tetra 15041-7
29362 Porphobilinogen 14882-5
23403 Interpretation 59462-2

Interpretation

Abnormal results are reported with a detailed interpretation which may include 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.

Method Description

An aliquot of urine is acidified and mesoporphyrin is added as an injection marker. Porphyrins in the acidified urine are separated by high-performance liquid chromatography, and the eluted porphyrins are quantified by comparison of their fluorescence intensity to that of known porphyrin standards.(Ford RE, Ou CN, Ellefson RD. Liquid chromatographic analysis for urinary porphyrins. Clin Chem. 1981;27[3]:397-401; de Andrade VL, Mateus ML, Aschner M, Dos Santos AM. Assessment of occupational exposures to multiple metals with urinary porphyrin profiles. J Integr OMICS. 2018;8(1):216. doi:10.5584/jiomics.v8i1.216)

 

Porphobilinogen (PBG) in urine is quantified by liquid chromatography tandem mass spectrometry after addition of stable isotope-labeled PBG internal standard and solid-phase extraction.(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;47[9]:1627-1632; Louleb M, Galvan I, Latrous L, et al. Detection of porphyrins in hair using capillary liquid chromatography-mass spectrometry. Int J Mol Sci. 2022;23[11]:6230.

Report Available

2 to 4 days

Specimen Retention Time

1 week

Reject Due To

  All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Method Name

High-Performance Liquid Chromatography (HPLC) with Fluorometric Detection/Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)

Urine Preservative Collection Options

Note: The addition of preservative must occur prior to beginning the collection.

Ambient (no additive)

No

Refrigerate (no additive)

No

Frozen (no additive)

No

50% Acetic Acid

No

Boric Acid

No

Diazolidinyl Urea

No

6M Hydrochloric Acid

No

6M Nitric Acid

No

Sodium Carbonate

Required

Thymol

No

Toluene

No

**Protect specimen from light.