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PORQT / PQNU-M
PORPHYRINS, QUANTITATIVE, 24-HOUR URINE

Test Code PORQT / PQNU-M 
Test PORPHYRINS, QUANTITATIVE, 24-HOUR URINE 
Methodology High-Performance Liquid Chromatography (HPLC) with Fluorometric Detection. Includes quantitation of coproporphyrins, uroporphyrins, and intermediate porphyrins (heptacarboxyl, hexacarboxyl, and pentacarboxyl). Includes liquid chromatography-tandem mass spectrometry (LC-MS/MS) determination of porphobilinogen. 
Description The measurement of porphobilinogen (PBG) in urine is important in the diagnosis of acute, neurologic porphyrias including acute intermittent porphyria (AIP), hereditary coproporphyria (HCP), and variegate porphyria (VP). Urinary porphyrin determination is helpful in the diagnosis of these disorders, as well as other porphyrias including congenital erythropoetic porphyria (CEP) and porphyria cutanea tarda (PCT). 
Specimen 20-50 mL (minimum: 15 mL) from a 24-hour collection. Add 5 g of sodium carbonate as preservative at start of collection. This preservative is intended to achieve a pH of > 7.0. See "Urine Preservatives" for multiple collections. Send specimen frozen in a plastic 60-mL urine bottle. Protect specimen from light.

NOTE:
1. DO NOT SUBSTITUTE SODIUM BICARBONATE FOR SODIUM CARBONATE.
2. The pH will generally fall between 8-10 if the proper preservative (5.0 g sodium carbonate) was added to the container before the collection was started.
3. The patient should be off medications for at least one week. If clinically inappropriate to discontinue medications, forward a list of medications with the specimen.
4. Patient should abstain from alcohol for at least 24 hours prior to collection, as well as during collection.
5. 24-HOUR VOLUME IS REQUIRED ON THE REQUEST FORM FOR PROCESSING.
6. Follow "Urine Collections" instructions. 

Reference Values UROPORPHYRINS (octacarboxyl)
< or =30 nmol/24 hours
HEPTACARBOXYLPORPHYRINS
< or =9 nmol/24 hours
HEXACARBOXYLPORPHYRINS
< or =8 nmol/24 hours
PENTACARBOXYLPORPHYRINS
< or =10 nmol/24 hours
COPROPORPHYRINS (tetracarboxyl)
Males: < or =230 nmol/24 hours
Females: < or =168 nmol/24 hours
PORPHOBILINOGEN
< or =2.2 mcmol/24 hours

See "Porphyrinogens, Porphyrins, and Porphyrias". 

Analytic Time 2 Days 
Day(s) Test Set Up Monday through Friday 
CPT Code(s) 84110  Porphobilinogen, quantitative
84120  Porphyrins, quantitation and fractionation

Special Instructions