Porphyrins & Porphobilinogen

Label Mnemonic:	PBGPU
Epic code:	LAB7365
Downtime form:	Doctor/Provider Orders - Pathology Core and Specialty Care Nursery

Commercial Mailout Laboratory
6240-8 RCP
356-8593

Specimen(s):

Urine (24 hr or random) More information

Specimen Instructions:

Refrigerate during 24 hr collection in dark plastic container. The most important aspect of specimen preservation is adequate refrigeration during collection, storage, and transport. Protect from light during collection, storage, and shipment. Record total volume and collection time interval on transport tube and test request form.

Collection Medium:

Urine - 24 hour/timed dark plastic urine container

Minimum:

24 hr collection in dark plastic container and refrigerate during entire collection and submission to University of Iowa Hospitals and Clinics laboratory. Containers available from Pharmacy.

24 hr collection or random urine
  Preferred Minimum:  8 mL aliquot of urine
  Absolute Minimum:  4 mL aliquot or urine

Rejection Criteria:

Body fluids other than urine.

Turn Around Time:

2-5 days upon receipt at reference laboratory

Reference Range:

Components:            Reference Interval:
 Uroporphyrin           0-4 μ mol/mol crt
 Heptacarboxylate       0-2 μ mol/mol crt
   Porphyrin
 Coproporphyrin I       0-6 μ mol/mol crt
 Coproporphyrin III     0-14 μ mol/mol crt
 Porphobilinogen, Urine 0.0-8.8 μ mol/L
 Porphobilinogen,       0.0-11.0 μ mol/d
   Urine (24-hour)
 Creatinine (24-hour)   Male (mg/d)           Female (mg/d)
                        3-8 yrs: 140-700      3-8 yrs: 140-700
                        9-12 yrs: 300-1300    9-12 yrs: 300-1300
                        13-17 yrs: 500-2300   13-17 yrs: 400-1600
                        18-50 yrs: 1000-2500  18-50 yrs: 700-1600
                        51-80 yrs: 800-2100   51-80 yrs: 500-1400
                        81+ yrs: 600-2000     81+ yrs: 400-1300

Note:  Urine porphyrins are useful for the evaluation of cutaneous 
photosensitivity to exclude porphyria cutanea tarda (PCT). Urine 
porphobilinogen (PBG) is useful for the evaluation of neurologic and/or 
psychiatric symptoms to exclude acute porphyrias such as acute 
intermittent porphyria (AIP).

Interpretive Data:

Results are normalized to creatinine concentration and reported as a ratio of amounts (micromoles of porphyrin/moles of creatinine).

Results for random urine specimens are normalized to creatinine (CRT) concentration and reported as a ratio of amounts (millimoles of PBG/mole of creatinine). Porphobilinogen (PBG) in a random urine specimen is used to evaluate an attack of acute porphyria. Slight increases in urinary PBG are associated with acute porphyrias other than acute intermittent porphyria (AIP) and may indicate a resolving or treated acute porphyria. Urinary PBG in excess of two times the upper reference limit is consistent with acute porphyria. Per 24h calculations are provided to aid interpretation for collections with a duration of 24 hours and an average daily urine volume. For specimens with notable deviations in collection time or volume, ratios of analytes to a corresponding urine creatinine concentration may assist in result interpretation. Per 24h calculations are provided to aid interpretation for collections with a duration of 24 hours and an average daily urine volume. For specimens with notable deviations in collection time or volume, ratios of analytes to a corresponding urine creatinine concentration may assist in result interpretation.

Comments:

Submit collection dates and times on requisition.  Includes 
Uroporphyrins, Heptacarboxylporphyrins, Coproporphyrins, 
Porphobilinogens, and Creatinine value.  Protect from strong light; 
refrigerate during collection.  The most important aspect of specimen 
preparation is adequate refrigeration during collection, storage, and 
transport.

Samples collected according to refrigerated guidelines are viable for 4 
days ONLY refrigerated.

Test Limitations:

Urine porphyrins are useful for the evaluation of cutaneous photosensitivity to exclude porphyria cutanea tarda (PCT). Evaluation of neurologic and/or psychiatric symptoms associated with acute porphyrias such as acute intermittent porphyria (AIP) requires urine porphobilinogen (PBG) testing.

Methodology:

High Performance Liquid Chromatography/Quantitative Spectrophotometry/ Quantitative High Performance Liquid Chromatography-Tandem Mass Spectrometry

CPT Code:

84120 Porphyrins, urine; 84110 PBG, urine

See also:
Aminolevulinic Acid, Urine (24 hour or random)
Porphobilinogen, Qualitative, Urine, Random

See Additional Information:
Urine Tests Requiring Preservatives, Refrigeration or Special Containers