Porphyria

Acute intermittent porphyria presents with intermittent abdominal pain that resembles the clinical picture of acute abdomen. Since the origin of the pain is neurologic, there is no fever and leukocytosis. Between the attacks, the patient fully recovers from the pain. Vomiting and constipation are also very common.

Any part of the nervous system may be involved with autonomic and peripheral neuropathy [4] [5]. Peripheral neuropathy may be symmetric or asymmetric. In extreme cases, even quadriplegia or respiratory paralysis may occur. Seizures and psychiatric disorders may also occur in the patients of acute intermittent porphyria. These disorders include depression, anxiety and frank psychosis.

Hypertension and tachycardia are also seen in most of the patients.

In porphyria cutanea tarda, the patient presents with bullous eruptions on the skin when exposed to sunlight. When the eruptions heal, scarring may take place.

The diagnosis of acute intermittent porphyria is made by the use of the following investigations.

• Serum electrolytes: The patients of acute intermittent porphyrias often have hyponatremia which is detected by examination of the serum electrolytes.
• Urine examination: The freshly void urine of the patients of acute intermittent porphyria is normal in color. However, when it is allowed to stand with exposure to light and air, it may turn black in color. The diagnosis is confirmed by increased amount of porphobilinogen in the urine during an attack.

The diagnosis of other types of porphyrias can also be made by similar demonstration of porphyrins in the urine or feces [6] [7]. Congenital porphyrias may be diagnosed prenatally by specialized tests [8].

The treatment of acute intermittent porphyria is mainly supportive and consists of the following principles.

• If the patient is hyponatremic, the amount of sodium in the blood should be corrected.
• Analgesics are given for pain. Because of the severity of the pain, narcotics may be given. Celiac plexus injection may be required in cases with extremely unbearable pain [9].
• Intravenous glucose is given in order to maintain a high level of carbohydrates in the patient.
• The symptoms of nausea and vomiting are managed by giving ondansetron [10].
• Intravenous infusion of hemin is given once or twice a day according to a calculate dose of 4 mg/kg body weight. It appears to be of some benefit in these patients but may cause the side effects of phlebitis and coagulopathy.

Porphyrias are associated with lifelong morbidity. If porphyrias are not diagnosed early and managed properly, they are fatal [2]. There is also a high risk for the development of hepatocellular carcinoma in the patients with acute hepatic porphyrias [3].

Porphyrias are primarily inherited metabolic disorders. All forms of porphyrias except congenital erythropoietic porphyria are autosomal-dominant disorders, the latter being autosomal-recessive.

Rarely, porphyrias may be acquired. A fungicide called hexachlobenzene is documented to have caused porphyrias in Turkey in the fifth decade of the twentieth century [1]. Alcohol is known to be a precipitating factor for porphyria cutanea tarda.

The peak incidence of acute intermittent porphyria is seen in the people around 30 years of age. The prevalence ranges from one case per 100,000 population in the United States to as high as 60 to 100 cases in northern Sweden. Women are affected much more commonly as compared to males.

Porphyrias result from the excess production of porphyrins - the intermediate products in the biosynthesis of heme. This occurs when there is a deficiency of function of one or more enzymes involved in the normal biosynthesis of heme.

Acute intermittent porphyria is caused by the deficiency of the function of an enzyme called porphobilinogen deaminase. This leads to an increased excretion of aminolevulinic acid and proporphobilinogen in the urine.

Inherited types of porphyrias can not be prevented. However, the precipitating factors of the attacks can be removed. These include certain drugs and alcohol. Alcohol intake is to be strongly restricted in the patients of porphyria cutanea tarda. Screening of other family members of the patients should be done with measurement of erythrocyte porphobilinogen, amino-levulinic acid (ALA) synthetase and other common porphyrins. The patients with hepatic porphyrias should be screened for signs of hepatocellular carcinoma.

Porphyrias are a group of usually inborn errors of metabolism. They are characterized by abnormalities of the enzymes that are involved in the biosynthesis of heme - the iron containing component of hemoglobin. Deficiency of the function of these enzymes results in the overproduction and accumulation of intermediate compounds in the biosynthetic pathway of heme formation. These intermediate compounds are named porphyrins.

Porphyrias can be classified according to several criteria. In porphyrias, excess production of porphyrins can occur either in the liver or in the bone marrow. The former are known as hepatic porphyrias whereas the latter are known as erythropoietic porphyrias. Acute intermittent porphyrias, hereditary porphyrias, variegate porphyrias and porphyria cutanea tarda are all hepatic porphyrias whereas congenital porphyrias and erythropoietic protoporphyria are erythropoietic porphyrias.

Porphyrias can also be classified according to their clinical presentations. The porphyrias that have an acute clinical picture include acute intermittent porphyria and variegate porphyria. On the other hand, porphyria cutanea tarda and erythropoietic protoporphyria have a subacute clinical picture. Acute intermittent porphyria is the most important type of porphyrias.

Porphyrias are a group of diseases in which the body is unable to normally form a component of red blood cells’ pigment because of a defect in any level of the synthetic pathway. Because of this, there is an accumulation of the intermediary compounds of the pathway.

These compounds accumulate in amounts that are toxic to the body and cause a variety of symptoms. For better quality of life, the disease should be diagnosed and treated early.

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