Porphyrins

Latest Edit: Hector 2014-03-24 (EDT)

See Also	Lab Tests

Porphyrin testing is used to help diagnose and monitor porphyrias disorders. These disorders are either classified as neurological porphyrias or cutaneous porphyrias.

Discussion

• Most porphyrin tests detect and measure the by-products or heme synthesis. Heme is an iron-containing pigment that is a necessary component of hemoglobin and a number of other proteins. If there is a deficiency in one of the enzymes involved in the production of hemoglobin that porphyrins such as uroporphyrin, coproporphyrin, and protoporphyrin can build up in the body's fluids and tissues and can be toxic to the body.
• Most porphyrin disorders are inherited.
• Indications for the test includes symptoms that suggest a neurologica porphyria (e.g. abdominal pain, tingling or numbness in the hands or feet, muscular weakness and/or alterations in thought or mood) or a cutaneous porphyria (e.g. redness, blistering, or scarring of sun-exposed skin).
• Neurologic porphyrias are associated with acute attacks involving the nervous system and/or gastrointestinal tract. There are four neurological porphyrias:

1. acute intermitent porphyria (AIP)
2. variegate porphyria (VP)
3. hereditary coproporhyria (HCP)
4. ALA dehydratase deficiency prophyria (ADP) which is very rare.

• Symptoms of acute neurologic porphyrias includes:

• Abdominal Pain
• Constipation
• Peripheral Neuropathy - tingling, numberness or pain in the hands and feet
• Muscle Weakness
• Urinary retention
• Confusion, hallucinations

• Acute neurologic porphyrias may last for days or weeks. Attacks can be triggered by drugs, environmental toxins, dietary changes, stress and exposure to toxic substances.

• Cutaneous prophyrias product skin-related symptoms. There are three cutaneous porphyrias:

1. prophyria cutanea tarda (PCT)
2. erythropoietic protoporphyria (EPP)
3. congenital erythropoietic porphyria (CEP)

• Symptoms of cutaneous porphyrias includes:

• blisters
• scarring
• hyperpigmentation
• redness
• itching
• burning
• swelling

Patient Preparation

• Testing for porphyrins can be done as a blood test, a random or 24-hour urine sample or as a stool sample.
• No preparation is required, yet if a neurologic porphyria is suspected, the sample should be collected during an acute attack.

Interfering Factors

• Environmental Toxins
• Stress
• Dietary changes

Clinical Implications

Interpreation of the patterns can be difficult and should be done by a physician or laboratory scientist with expertise in porphyrias.

Associated Tests

• Porphobilinogen deaminase (PBG-D), Uroporphyrinogen Decarboxylase