Porphyrins urine

Specimen:

Random urine, protected from light and refrigerated if immediate analysis is not possible.

Method:

Porphyrins (total): spectrophotometry, fluorometry.

Uroporphyrin, coproporphyrin: HPLC.

Reference Interval:

Porphyrins (total): < 250 nmol/L

Uroporphyrin: < 40 nmol/L

Coproporphyrin: < 240 nmol/L

Application:

The test is only reliable if the patient is symptomatic when the specimen is collected.

Diagnosis of acute neurological porphyrias (acute intermittent porphyria, porphyria variegata, hereditary coproporphyria) or porphyria cutanea tarda.

It may be used to diagnose lead poisoning but blood lead is the recommended test.

Interpretation:

Increased coproporphyrin occurs in porphyria variegata, hereditary coproporphyria, and the porphyrinurias due to lead poisoning and cholestasis.

Increased uroporphyrin occurs in porphyria cutanea tarda, in which increased hepta-, hexa-, and penta-carboxylporphyrins are also found.

Uroporphyrin is also increased in acute intermittent porphyria due to chemical conversion from porphobilinogen in urine.

Reference:

Lecha M et al. Dermatol Ther. 2003; 16(1): 65-72.