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Porphyrins, Quantitative, 24-Hour Urine

CPT: 84120
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Synonyms

  • Coproporphyrin
  • Uroporphyrin

Test Includes

Coproporphyrins I and III; uroporphyrins; heptacarboxylporphyrins; hexacarboxylporphyrins; pentacarboxylporphyrins


Special Instructions

The test request form must state 24-hour collection volume.


Expected Turnaround Time

4 - 7 days



Related Documents


Specimen Requirements


Specimen

Urine (24-hour), protected from light


Volume

2-mL aliquot


Minimum Volume

1.5-mL aliquot (Note: This volume does not allow for repeat testing.)


Container

12-mL plastic transport tube without preservative.


Collection

Instruct patient to void at 8 AM (or 8 PM) and discard the specimen. Then collect all the urine, including the final specimen voided at the end of the 24-hour collection period (ie, 8 AM [or 8 PM] the following day). Mix well. Measure and record total urine volume on the test request form, along with the patient's name, date, and time collection started and finished. Transfer required aliquot into a LabCorp amber plastic transport tube with amber cap (LabCorp N° 23598). (If amber transport tubes are unavailable, cover transport tube completely, top and bottom, with aluminum foil. Identify specimen with patient's name directly on the amber transport tube and on the outside of the aluminum foil. Secure with tape.) Specimen must be kept refrigerated during transport.


Storage Instructions

Refrigerate and protect from light.


Stability Requirements

Temperature

Period

Room temperature

Unstable

Refrigerated

7 days

Frozen

14 days

Freeze/thaw cycles

Stable x3


Causes for Rejection

Stored specimen not refrigerated; specimen exposed to light; acid preservative; pH <3


Test Details


Use

Evaluate porphyrias, including those involving deficiencies of enzymes that are needed for heme synthesis and chemical porphyrias.

In congenital erythropoietic porphyria, elevations of urinary uroporphyrin and coproporphyrin occur, with the former exceeding the latter.

In acute intermittent porphyria, porphobilinogen and δ-aminolevulinic acid are elevated in acute attacks, and mild increases of urinary uroporphyrin and coproporphyrin may be found. Porphobilinogen is increased in many but not all patients with acute intermittent porphyria in latent periods. Quantitative porphobilinogen is a better test than δ-aminolevulinic acid overall for acute intermittent porphyria, but both are used (as well as the Watson-Schwartz test).1

Coproporphyrin and porphobilinogen excretion in urine are markedly increased during acute attacks of hereditary coproporphyria, increase of urinary uroporphyrin may be found, and increased fecal coproporphyrin III is described.

In variegate porphyria in acute attacks, results are similar to those of acute intermittent porphyria. Porphobilinogen and ALA are prone to become normal between attacks. Urine coproporphyrin exceeds uroporphyrin excretion during acute attacks.

Chemical porphyrias occur. Porphyrinogenic chemicals include certain halogenated hydrocarbons that cause the excretion of increased uroporphyrin.

In lead poisoning elevation of δ-aminolevulinic acid greater than that of porphobilinogen occurs and porphobilinogen may be normal. Urinary coproporphyrin characteristically is increased. Free erythrocyte protoporphyrin is increased. Toxins such as lead interfere with heme synthesis and cause porphyrinuria.

Increased urine excretion of uroporphyrinogen, uroporphyrin, and coproporphyrin occurs in porphyria cutanea tarda. It is found in (1) middle-aged men who like ethanol, (2) young women on oral contraceptives, and in (3) subjects on dialysis. These patients do not excrete increased porphobilinogen, but they may have slight elevations of δ-aminolevulinic acid.

Two Types of Porphyria*†

Cutaneous Porphyria

Clinical Notes

Neurologic Porphyria

Clinical Notes

*Note: Low urine values are meaningless. Only greatly increased values (10-15 times the upper limit of the reference interval) have clinical significance for porphyrias.

†Timing of urine collection for the investigation of cutaneous porphyria is not as critical as in neurologic porphyrias in which PBG screening test should be collected when the patient is symptomatic.

Congenital erythropoietic porphyria (CEP)

Very rare; generally diagnosed in childhood

Acute intermittent porphyria (AIP)

80% of neurologic porphyrias

Protoporphyria (PP)

Seen in adolescents

Variegate porphyria (VP)

Porphyria cutanea tarda (PCT)

90% (most common) of cutaneous porphyrias; seen in middle age

Coproporphyria (CP)

The accompanying flow diagrams outline steps for the investigation of cutaneous and neurologic porphyrias.


Limitations

Increased porphobilinogen may occur in patients on oral contraceptives. This test and δ-aminolevulinic acid will not detect protoporphyria. Coproporphyrinuria alone lacks specificity and sensitivity for lead testing. Erythrocyte uroporphyrinogen-1-synthase is decreased in latent acute intermittent porphyria, and is needed in patients with possible latent acute intermittent porphyria. Quantitative porphobilinogen is of value in active and in many cases of latent acute intermittent porphyria, but will miss some of the latter when compared to red cell uroporphyrinogen-1-synthase.


Methodology

High-pressure liquid chromatography (HPLC) with fluorometric detection


Reference Interval

• Coproporphyrin (CP) I: 0−24 μg/24 hours

• Coproporphyrin (CP) III: 0−74 μg/24 hours

• Heptacarboxylporphyrins (7-CP): 0−4 μg/24 hours

• Hexacarboxylporphyrins (6-CP): 0−1 μg/24 hours

• Pentacarboxylporphyrins (5-CP): 0−4 μg/24 hours

• Uroporphyrins (UP): 0−24 μg/24 hours

See table.

Pattern of the Different Porphyrias

Disease

Uro

Hepta

Hexa

Penta

Copro I

Copro III

+ = increased; ++ = strongly increased; n = normal; v = varies.

Values from: Doss M. Porphyrinstoffwechsel. In: Greiling H, Gressner AM (Hrsg). Lehrbuch der Klinischen Chemie und Pathobiochemie. Dritte Auflage. Stuttgart, Germany: Schattauer Verlag.

Values marked with * and ** respectively, are derived from:

*Hindmarsh JT, Oliveras L, Greenway DC. Biochemical differentiation of the porphyrias. Clin Biochem. 1999 Nov; 32(8):609-619.

**Elder GH, Smith SG, Smyth SJ. Laboratory investigation of the porphyrias. Ann Clin Biochem. 1990 Sep; 27(Pt 5):395-412.

Porphyria cutanea tarda (PCT)

++

++

+

+

+*

+*

Acute intermittent porphyria (AIP)

++

+

+

++

+*

++*

Porphyria variegata (VP)

++

+

+

++

+*

++*

Hereditary coproporphyria (CP)

+

+

+

++

n*

++*

Protoporphyria

v

n

n

v

+*

v

Morbus Gunther

++

+

+

+

++**

Porphobilinogen synthase deficiency

+

+

+

++

++


Additional Information

Increased urine porphyrin excretion may be secondary to other diseases (eg, hepatobiliary diseases), especially coproporphyrin excretion. These are secondary porphyrinurias. They lack increased urinary porphobilinogen or Δ-ALA, with the important exception of lead poisoning.2 The table provides an abbreviated overview of the porphyrias. Porphyrin fractionation of plasma can be done. Increases of urine porphyrins are found with congenital erythropoietic porphyria, acute intermittent porphyria, hereditary coproporphyria, variegate porphyria, and porphyria cutanea tarda.

Porphyrias: Overview

Disorder

Inheritance

Age of Clinical Onset

Primary Organ Involvement

Useful Tests

Primary Symptoms

Congenital erythropoietic porphyria

Autosomal recessive

Birth−5 y

Erythroid cells

Urinary porphyrins;

Fecal porphyrins;

Uroporphyrinogen III synthase, erythrocytes

Severe photosensitivity

(Günther disease)

Rare

Fluorescence of a diaper under Wood light

Red urine;

diaper stains;

hemolytic anemia

Acute intermittent porphyria

Autosomal dominant

Adults

Hepatic, probably erythroid cells

Urine porphobilinogen;

Porphobilinogen deaminase, erythrocyte;

Urine porphyrins;

Urinary δ-aminolevulinic acid;

Erythrocyte uroporphyrinogen-1-synthase;

Fecal porphyrins

Mild/severe neurologic/visceral (autonomic) symptoms

Precipitating causes include barbiturates, hydantoins, sulfonamides

Most common acute hepatic porphyria in US

Acute attacks

Hereditary coproporphyria

Autosomal dominant

Adults

Hepatic, possibly erythroid cells

Urine PBG and ALA in acute attacks;

Urine porphyrins including coproporphyrin;

Fecal porphyrins;

Plasma porphyrins

Similar to variegate porphyria;

acute attacks

Variegate porphyria

Autosomal dominant

Adults

Hepatic, possibly erythroid cells

Urine PBG and ALA in acute attacks;

Urine porphyrins;

Fecal porphyrins;

Plasma porphyrins;

Erythrocyte uroporphyrinogen-1-synthase

Mild/severe photosensitivity, neurologic/visceral symptoms;

acute attacks

Porphyria cutanea tarda

Autosomal dominant, type II (inherited type); sporadic type also known; most common porphyria in US

Adults

Hepatic, possibly erythroid cells; photosensitivity

Urine porphyrins;

Plasma porphyrins;

Uroporphyrinogen decarboxylase, type II (RBCs)

Similar to variegate porphyria;

photosensitization;

liver damage

Protoporphyria

Autosomal dominant

Usually childhood

Erythroid cells, probably liver

Protoporphyrin, free erythrocyte

Photosensitization;

liver damage

Acquired (intoxication) porphyria

Acquired

Children and adults

Hepatic, erythroid cells

Erythrocyte porphyrins;

Urinary δ-aminolevulinic acid;

Urine porphobilinogen;

Urine porphyrins;

Fecal porphyrins

Mild photosensitivity

Fecal porphyrin examination for hereditary coproporphyria, variegate porphyria, and protoporphyria can be used for adult patients. Stool examination for coproporphyrin and protoporphyrin is recommended for diagnosis of variegate porphyria.3

Neurologic dysfunction occurs in the hepatic porphyrias, the types of porphyria in which acute attacks develop: acute intermittent porphyria, variegate porphyria, hereditary coproporphyria, and ALA dehydrase deficiency. Abdominal pain, caused by autonomic neuropathy, occurs with acute attacks (eg, acute intermittent porphyria). It is the most common symptom of acute intermittent porphyria.2

Cutaneous aspects of the porphyrias are caused by photosensitization (eg, porphyria cutanea tarda, protoporphyria).

Hepatic complications are found with porphyria cutanea tarda and protoporphyria. Fluorescence is demonstrable in liver biopsies from patients with the former, as well as siderosis. Crystalline deposits may be found in protoporphyria.2 The amount of porphobilinogen excreted in acute intermittent porphyria is usually greater than the excretion of δ-aminolevulinic acid (Δ-ALA). When there is more Δ-ALA, another diagnosis should be considered, including lead poisoning, another type of porphyria, or hereditary tyrosinemia.2 See also Zinc Protoporphyrin (ZPP) [010170], which pertains to lead poisoning, and erythropoietic protoporphyria. The differential diagnosis of lead poisoning is relevant.4


Footnotes

1. Tschudy DP. Porphyrins. In: Brown SS, Mitchell FL, Young DS, eds. Chemical Diagnosis and Disease. Amsterdam, Holland: Elsevier/North Holland Biomedical Press;1979:1039-1058.
2. Bloomer JR, Bonkovsky HL. The porphyrias. Dis Mon. 1989 Jan; 35(1):1-54.
3. Muhlbauer JE, Pathak MA, Tishler PV, Fitzpatrick TB. Variegate porphyria in New England. JAMA. 1982 Jun 11; 247(22):3095-3102.
4. Bird TD, Wallace DM, Labbe RF. The porphyria, plumbism, pottery puzzle. JAMA. 1982 Feb 12; 247(6):813-814.

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
003194 Porphyrins, Qn, 24 Hr Ur. 121042 Uroporphyrins (UP) ug/L 11228-4
003194 Porphyrins, Qn, 24 Hr Ur. 121043 Uroporph(UP),24hr ug/24 hr 3113-8
003194 Porphyrins, Qn, 24 Hr Ur. 121044 Heptacarboxyl (7-CP) ug/L 2407-5
003194 Porphyrins, Qn, 24 Hr Ur. 121045 Heptacarb(7-CP),24hr ug/24 hr 24462-4
003194 Porphyrins, Qn, 24 Hr Ur. 121046 Hexacarboxyl (6-CP) ug/L 27400-1
003194 Porphyrins, Qn, 24 Hr Ur. 121047 Hexacarb(6-CP),24hr ug/24 hr 9527-3
003194 Porphyrins, Qn, 24 Hr Ur. 121048 Pentacarboxyl (5-CP) ug/L 11221-9
003194 Porphyrins, Qn, 24 Hr Ur. 121049 Pentacarb(5-CP),24hr ug/24 hr 9730-3
003194 Porphyrins, Qn, 24 Hr Ur. 121050 Coproporphyrin (CP) I ug/L 47253-0
003194 Porphyrins, Qn, 24 Hr Ur. 121051 Coproporph(CP)I,24hr ug/24 hr 6877-5
003194 Porphyrins, Qn, 24 Hr Ur. 121052 Coproporphyrin (CP) III ug/L 47254-8
003194 Porphyrins, Qn, 24 Hr Ur. 121053 Copropor(CP)III,24hr ug/24 hr 6878-3

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