What a Porphyria Urine Sample Measures

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Porphyria [por·fee·ree·uh] is a group of disorders caused by abnormal function of the enzymes involved in the production of heme. Heme is a major component of hemoglobin, the oxygen-carrying component of red blood cells. Heme is also produced in the liver, where it is used in the production of various important cytochrome enzymes that help synthesize and break down hormones.

The production of heme in the bone marrow and liver will normally create a certain amount of porphyrins, but if the heme-producing enzymes are out of balance, porphyrins can build up and become toxic.

Porphyria

The terms "porphyrin" and "porphyria" come from the Greek word "porphyrus," meaning purple. The name was given to these chemicals because people who have a buildup of porphyrin can have discolored urine that has a dark or reddish hue, or it becomes darker the longer it is exposed to air.

If your doctor suspects you have porphyria based on your symptoms, the doctor will order the appropriate screening test. This typically includes analysis of a urine sample from the patient.

Keep reading to learn more about how a urine sample can be used to help diagnose these rare enzyme disorders.

An unseen person holding a urine sample.

cglade/Getty

Types of Porphyria

There are several types of porphyria, and each leads to an accumulation of a different type of porphyrin. Below are some of the types of porphyria and the enzyme that causes them:

  • Acute Intermittent porphyria (AIP): Prophobilinogen deaminase
  • Hereditary coproporphyria (HCP): Coproporphyrinogen oxidase
  • Variegate porphyria (VP): Protoporphyrinogen oxidase
  • Porphyria cutanea tarda (PCT): Uroprophyrinogen decarboxylase
  • Hepatoerythropoetic porphyria (HEP): Uroprophyrinogen decarboxylase
  • Congenital erythropoietic porphyria (CEP): Uroporphyrinogen III synthase
  • Erythropoietic protoporphyria (EPP): Ferrocheletase
  • X-linked protoporphyria (XLP): δ-aminolevulinic acid synthase
  • Delta-aminolevulinic acid dehydratase (ALAD) porphyria (ADP) (also written as δ-aminolevulinic acid dehydratase): alpha aminolevulinic acid synthase (also written as α-aminolevulinic acid synthase)

With each type, porphyria is the result of the overproduction or deficiency of a specific enzyme involved in the production of heme. There are many types of porphyria, but, overall, these conditions are rare.

How Common Is Porphyria?

Only about 1 in 10,000 people have the most common form of porphyria (PCT), while 1 in 1 million people have CEP. For the rarest form of the condition (ADP), only six cases have ever been recorded.

What Causes Porphyria? 

Porphyrias usually develop because of an inherited genetic mutation. The mutation causes problems with the enzymes that work together to create blood cells.

What Are Enzymes?

Enzymes are chemicals in the body (generally proteins) that speed up a chemical process. Many types of enzymes are used by the body, with each one playing a role in the chemical reactions that take place.

The production of a molecule that contains iron (heme)p requires the work of several enzymes to create hemoglobin.

The production of the protein in your red blood cells that carries oxygen throughout your body (hemoglobin) is complex. If one step is off balance, porphyrins—which are a natural by-product of the process—can build up to toxic levels. The part of the process that gets disrupted and the type of porphyrin that is produced depends on the enzyme that is affected by the genetic mutation.

There are also rare forms of porphyria that are not caused by genetic mutations. These conditions are called acquired porphyrias. Possible causes of acquired porphyria include:

Symptoms 

In addition to being grouped by the type of enzyme that is disrupted, porphyrias are also classified by how they affect the body and what symptoms they cause.

Acute Porphyria

Acute porphyrias evolve over several days and get worse with time. These types are sometimes called neurologic porphyrias. Porphyrias that are included in this category include:

  • Acute intermittent porphyria (AIP)
  • Hereditary coproporphyria (HCP)
  • Variegate porphyria (VP)
  • δ-aminolevulinic acid dehydratase (ALAD) porphyria

Abdominal pain is a common primary symptom in this category of porphyria. Other symptoms may also include:

Two porphyrias in this category—variegate porphyria and hereditary coproporphyria—may also cause symptoms like skin blistering after exposure to sunlight.

Most people (80%–90%) who carry genetic mutations for AIP, HP, and HCP never have symptoms or only have a few severe attacks of symptoms in their lifetime.

Cutaneous Porphyria

Cutaneous porphyrias mostly affect the skin, creating fragile or blistering areas on the backs of the hands, forearms, ears, neck, and face.

The main forms of porphyria that fall into this category are:

  • Porphyria cutanea tarda (PCT)
  • Hepatoerythropoietic porphyria (HEP)
  • Congenital erythropoietic porphyria (CET)
  • Erythropoietic protoporphyria (EPP)
  • X-linked protoporphyria (XLP)

While CEP and HEP can develop in childhood, PCT only occurs in adults. Sensitivity to light and pain, inflammation, or blistering after sun exposure are the main symptoms of porphyrias in this group.

Diagnosis 

The variety of symptoms that can occur with different types of porphyria can make it tricky to diagnose the condition. In many cases, a diagnosis only comes after other conditions have been ruled out.

Polyphorin tests are a common way to check the level of these chemicals in your body. The tests can be done using urine, stool, blood, or other body fluids.

With blood testing, a laboratory technician will remove a small amount of blood from your body—usually through a vein in your arm—for testing. When stool testing is done, your healthcare provider will give you a special container and instructions on where to bring the stool that you have collected at home.

Urine collection can be done in the following two ways when testing for porphyria:

  • A 24-hour urine collection can provide a more exact picture of your urine content. Urine is more concentrated in the morning or after you sleep; therefore, testing your first urine of the day can lead to skewed results. This test combines all of your urine over the course of 24 hours.
  • A random urine sample can be done at your doctor's office or a lab. These urine tests are easier to collect than a 24-hour collection is, but since the first urine of the morning is preferred, you might be sent home with a container to do the collection at home.

When one of the acute porphyrias is suspected, a spot urine sample is often the best test to use because rapid diagnosis and treatment is important. Rapidly detecting elevated urinary porphyrins can allow treatment to be initiated quickly.

If you're doing the collection at home, make sure to bring your urine sample to the doctor's office or lab as soon as possible after completion.

Where to Go

If you are having a random urine sample collected for testing, it can usually be done at your doctor's office and sent to a lab. Blood draws are sometimes performed in a doctor's office but are usually done in the lab.

If you are having a 24-hour urine or stool test, your doctor will send you home with a special container and instructions on how to do the collection, as well as where to bring it for testing.

Adults 

When completing a 24-hour urine collection, you will be given a special container to take home. You will collect all your urine over a 24-hour period. You will add your urine to the container in a specific way, as follows:

  • On the first day of the collection period, urinate in the toilet.
  • With your second urination of the day, begin collecting your urine and putting it into the designated container.
  • Keep the container capped and in a cool, dark place like a refrigerator between collections.
  • End the collection period with your first urine after you wake up on the second day.

Your doctor will give you instructions on how and where to bring your urine in for testing. Typically, you will bring the container to a lab.

Babies and Young Children 

A 24-hour urine collection can be harder in babies and young children who are not toilet trained and are still in diapers. There is a specific process for doing a urine collection in this case, which is:

  • Get the urine collection bag your doctor has given you. They are usually plastic and have an adhesive strip on one end.
  • Wash the area around your child's urethra.
  • Place the bag entirely over the penis or labia.
  • Once the bag is in place, your child can be diapered as usual.
  • As with adults, discard your child's first urine of the day for the first day.
  • Urine collection for young children can take several attempts, as they can easily dislodge the bag and cause the urine to be absorbed by the diaper. Once you have been successful, empty the bag into the collection contained provided by your doctor for a 24-hour period.
  • End the collection with your child's first urination on the second day.

Taking a Second Test

There are no special preparations for a random or 24-hour urine collection, however, you should be aware of things that could skew the results of porphyrin testing, which would require you to have to do a second test.

Some things that may alter the results of your urine test include:

  • Dehydration
  • Use of contrast dyes within a few days of the test
  • Contamination from stool or vaginal fluid
  • Urinary tract infections
  • Certain vitamins or medications
  • Extreme stress
  • Strenuous exercise

If your urine test is inconclusive, or your doctor wants a way to confirm a porphyria diagnosis, they may want you to have genetic or DNA testing to identify specific gene mutations.

Follow-Up Test Questions 

Depending on how your test is done and where the lab that is doing the testing is located, your results could be ready in as little as a few hours, or it may take several days.

While you wait, your doctor may give you information about porphyria and explain how to manage any symptoms.

There are no risks related to the test itself, but if you have blood testing done, you may have some tenderness or bruising at the collection site.

Understanding Your Results

Blood, urine, and stool testing will reveal the porphyrin levels in your body. There are several types of porphyrins, and each has an acceptable normal range. Anything above these ranges could signal an abnormally high amount of these chemicals.

For blood samples, the amounts are written in micrograms per deciliter (mcg/dL) or nanomoles per litre (nmol/L). The acceptable ranges of porphyrins are:

  • Total porphyrin levels: 0–1.0 mcg/dL (0–15 nmol/L)
  • Coproporphyrin level: <2 mcg/dL (<30 nmol/L)
  • Protoporphyrin level: 16–60 mcg/dL (0.28–1.07 µmol/L)
  • Uroporphyrin level: <2 mcg/dL (<2.4 nmol/L)

For 24-hour urine collections, the amounts are written as micrograms per 24-hour-period (mcg/24 hours). The reference ranges are:

  • Coproporphyrin (CP) I: 0–24 mcg/24 hours
  • Coproporphyrin (CP) III: 0–74 mcg/24 hours
  • Heptacarboxylporphyrins (7–CP): 0–4 mcg/24 hours
  • Hexacarboxylporphyrins (6-CP): 0–1 mcg/24 hours
  • Pentacarboxylporphyrins (5-CP): 0–4 mcg/24 hours
  • Uroporphyrins (UP): 0–24 mcg/24 hours

Treatment

If your test results reveal porphyria, treatment will depend on the type. Some people are tested because of a family history of porphyria and may not be experiencing any symptoms of the condition.

Preventive measures can be taken to prevent an acute episode, or flare-up (when symptoms worsen), including:

  • Avoiding drugs and alcohol
  • Avoiding sunlight and protecting skin when exposed to the sun

Medications that may trigger flare-ups can include:

Research on the most effective way to manage the underlying process that causes the condition is still underway, but there are a few prescription medications to treat specific types of porphyria, including:

  • Panhematin (hemin for injection) for acute porphyrias like AIP, VP, HCP, ADT
  • Givlaari (givosiran) for AIP, VP, HCP, ADT
  • Scenesse (afamelanotide) for EPP

Summary

Porphyria is a term that describes a group of rare conditions that are caused by abnormal function of the enzymes that help your body make heme. These conditions can cause symptoms like urine color changes, abdominal pain, and sensitivity to sunlight. It is usually diagnosed by analyzing a urine sample. The treatment for the condition depends on the type of porphyria.

A Word From Verywell

If you are diagnosed with porphyria, your doctor will explain what you need to know about the type that you have, including the options for treatment.

If you have had an acute episode of symptoms, know that many people with certain types of porphyria only have a few of these episodes in their lifetime. There are also ways that you can prevent flare-ups, such as by avoiding triggers and taking medication.

Frequently Asked Questions

  • What color is urine in porphyria patients?

    People with porphyria may have urine that is dark yellow to red or violet in color.

  • How do you know if you need a urine porphyrin test?

    Your doctor will order the test for you if you have a family history of porphyria or if your symptoms match one of the subtypes of the condition.

  • What’s the normal range of porphyrins in urine?

    The normal range of porphyrins depends on the specific porphyrin type being tested and the type of urine test that is being done. Your doctor will talk to you about the ranges that apply to your situation.

  • Does insurance cover a urine porphyrin test?

    Coverage for individual lab tests depends on your insurance plan. Most insurance plans will cover at least a portion of tests that are ordered if they are determined to be medically necessary by your doctor.

    If you are unsure about your insurance coverage, you may want to call your health insurance company before being tested for porphyria.

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10 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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