How Do Doctors Diagnose Porphyria?
Porphyria is a group of genetic disorders in which there are high levels of porphyrins in the blood and tissues. Each type of porphyria has different symptoms and disease progression. That’s why a series of exams and tests may be necessary to diagnose a patient with porphyria.
Physical exam and medical history
Your doctor first will give you a physical exam. He or she also will ask about your family medical history. Many porphyria cases are inherited, so that means another family member may have the disease.
Blood, urine, and stool tests
You may need to give a blood, urine, or stool sample for doctors to diagnose porphyria. A few milliliters of blood are sufficient for the test. In order to test a stool or urine sample, your doctor may give you containers that you can use at home to collect the samples. You then return the samples to the clinic or hospital for testing.
If your samples indicate that you have high levels of porphyrins in your blood, stool, or urine, then your doctor will arrange for other tests to diagnose porphyria.
Genetic testing for Porphyria
Mutations in genes that provide instructions for making enzymes that play a role in creating a compound called heme from porphyrins are what cause porphyrias. The body uses heme to make hemoglobin, the protein that binds oxygen in red blood cells. Heme also is important in the process of making energy in cells.
There are eight genes that play a role in making heme. These are: ALAD, ALAS2, CPOX, FECH, HMBS, PPOX, UROD, and UROS. Heme production requires all eight enzymes working in series. Genetic mutations in any of these genes can, therefore, cause cells not to be able to make heme. This results in porphyrins accumulating in cells and tissues.
Genetic testing can look for disease-causing mutations in any one of the genes that play a role in making heme and confirm a diagnosis of porphyria.
Last updated: July 28, 2020
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