Porphyria

General or Other | Emergency Medicine | Porphyria (Disease)


Description

The porphyrias are a group of different diseases, each caused by a specific abnormality in the heme production process.

Heme is a chemical compound that contains iron and gives blood its red color. The essential functions of heme depend on its ability to bind oxygen. Heme is incorporated into hemoglobin, a protein that enables red blood cells to carry oxygen from the lungs to all parts of the body.

Heme also plays a role in the liver where it assists in breaking down chemicals (including some drugs and hormones) so that they are easily removed from the body.

Porphyria symptoms arise mostly from effects on either the nervous system or the skin. Effects on the nervous system occur in the acute porphyrias (AIP, ADP, HCP and VP).

Causes and Risk factors

Normally, the body makes heme in a multi-step process. Porphyrins are made during several steps of this process. Patients with porphyria have a deficiency of certain enzymes needed for this process. This causes abnormal amounts of porphyrins or related chemicals to build up in the body.

There are many different forms of porphyria. The most common type is porphyria cutanea tarda (PCT).

Drugs, infection, alcohol, and hormones such as estrogen may trigger attacks of certain types of porphyria.

Diagnosis and Treatment

Proper diagnosis is often delayed because the symptoms are nonspecific. Skin manifestations can include burning, blistering and scarring of sun-exposed areas.

The treatment goal for acute attacks of porphyria is to decrease heme synthesis and reduce the production of porphyrin precursors. High doses of glucose (400 g/d) can inhibit heme synthesis and are useful for treatment of mild attacks.

People experiencing severe attacks, especially those with severe neurologic symptoms, should be treated with hematin in a dose of 4 mg/kg/d for 4 days. Pain control is best achieved with narcotics. Laxatives and stool softeners should be administered with the narcotics to avert exacerbating existing constipation. Treat seizures with Neurontin. Most classic antiseizure medicines can lead to acute porphyria attacks. ...