Intermittent acute porphyria

Intermittent acute porphyria is a congenital disturbance of the metabolism of porphyrins, which is characterized by an excessive excretion of porphyrin precursors, porphobilinogen, and δ-aminolevulinic acid during the clinical episodes of the disease. There is a clear evidence of familial incidence. It is transmitted as a dominant autosomic trait and is more frequent in women. The clinical manifestations consist of attacks of abdominal colic pain usually accompanied by nausea and vomiting and occasionally by fever and leukocytosis. Intense constipation, psychiatric disturbances, and neuromuscular anomalies also occur. The appearance of clinical symptoms may follow the use of certain drugs. The pathologic basis lies in an alteration of the central, peripheral, and autonomic nervous systems. The basic problem is apparently a defect or hypofunction of uroporphyrinogen I synthetase which causes an increase in the level of δ-aminolevulinic acid and porphobilinogen in urine. The most conclusive diagnositic test is to determine the activity of uroporphyrinogen I synthetase in the erythrocytes; this procedure, however, is not practicable in most cases and the normal method is to determine the levels of δ-aminolevulinic acid and porphobilinogen in urine. A simple, easy test is to expose fresh urine to sunlight, making it turn a dark color, though this test is not specific for intermittent acute porphyria. Treatment is based on an overload of carbohydrates, but recently success has been achieved with intravenous injection of hematin.