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Porphyrins - urine

Definition

Porphyrins help form many important substances in the body including hemoglobin, the protein in red blood cells that carries oxygen in the blood.

Porphyrins can be found in urine. A urine porphyrins test measures the amount of porphyrins in the urine.

Alternative Names

Uroporphyrin

How the test is performed

A 24-hour urine sample is needed.

• On day 1, urinate into the toilet when waking up in the morning.
• For the next 24 hours, every time you urinate, collect the urine in a special container. Keep it in the refrigerator or a cool place during the collection period.
• On day 2, urinate into the container in the morning when waking up. Close the container, and label it with your name, date, and time you finished.
• Return the container to your health care provider as instructed.

In infants:

Thoroughly wash the area around the urethra (the area where urine exits). Open the urine collection bag provided by your doctor. For boys, place the entire penis in the bag and attach it to the surrounding skin. For girls, place the bag over the labia.

You can diaper the baby as usual, over the collection bag.

Note: It may take a few tries to get the bag correctly into place. Check the infant frequently and change the bag after the infant has urinated. Drain the urine into the special container provided by your health care provider. Take the container to the laboratory or your health care provider as soon as possible.

How to prepare for the test

Extra collection bags may be necessary if the urine sample is being taken from an infant.

Your doctor may tell you to stop taking any medicines that may affect the test results. NEVER stop taking any medicine without first talking to your doctor.

Drugs that can affect test measurements include:

• Aminosalicylic acid
• Birth control pills
• Barbiturates
• Chloral hydrate
• Chlorpropamide
• Ethyl alcohol
• Griseofulvin
• Morphine
• Phenazopyridine
• Procaine
• Sulfonamides

How the test will feel

The test will feel the same as normal urination.

Why the test is performed

Your doctor will order this test if you have signs of porphyria or other disorders that can cause abnormal urine porphyrins.

Normal Values

Normal results vary. In general, for a 24-hour urine test, the range is about 50 - 300 mg (milligrams).

What abnormal results mean

Abnormal results may be due to:

• Liver cancer
• Hepatitis
• Lead poisoning
• Porphyria (several types)

References

Anderson K. The porphyrias. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 229.

McPherson R, Ben-Ezra J, Zhao S. Basic examination of urine. In: McPherson RA, Pincus MR. Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. Philadelphia, Pa: Saunders; 2006:chap 27.