Porphyrins, blood

How the Test is Performed:
Blood is drawn from a vein ( venipuncture ), usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) or blood pressure cuff is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to distend (fill with blood). A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding .

The sample is then placed in ice and taken immediately to the laboratory.

How to Prepare:
Fasting for 12 to 14 hours prior to this test is required. You may drink water right before the test.

If your child is to have this test performed it may be helpful to explain how the test will feel, and even practice or demonstrate on a doll. The more familiar your child is with what will happen to them, and the purpose for the procedure, the less anxiety they will feel.

How it Feels:
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing .

Risks:
Risks associated with venipuncture are slight:
  • excessive bleeding
  • fainting or feeling lightheaded
  • hematoma (blood accumulating under the skin)
  • infection (a slight risk any time the skin is broken)
  • multiple punctures to locate veins



Why this Test is Performed:
This test is used to diagnose porphyrin disorders involving red blood cells.

Normal Values:
This test specifically measures total porphyrin levels, but reference values for the individual components are also included:

  • total porphyrin levels: 16 to 60 mcg/dl
  • coproporphyrin levels: <2 mcg/dl
  • protoporphyrin levels: 16 to 60 mcg/dl
  • uroporphyrin levels: <2 mcg/dl

Note: mcg/dl = micrograms per deciliter

Abnormal Results:
Increased levels of coproporphyrins may indicate:

Increased protoporphyrin levels may indicate:

Increased uroporphyrin levels may indicate:



Cost:
Information not available.

Special Considerations:
Failure to comply with dietary restrictions prior to the test may alter and invalidate test results.

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.