Acute porphyric attack, which is characterized by abdominal pain and neurologic manifestations, is a feature in acute intermittent porphyria, variegate porphyria, and hereditary coproporphyria. In all three conditions the porphyrin precursors porphobilinogen and 5-aminolevulinic acid are accumulated during attacks. In symptomatic patients the specific porphyria can easily be diagnosed by specific laboratory tests. Most porphyrias are inherited in autosomal dominant fashion, but the penetrance of the disease varies greatly. In many porphyrias, the majority of patients remain asymptomatic throughout their lives.
Biochemical tests are often inaccurate in the diagnosis of latent cases of porphyria.
When the underlying mutation in an affected family is known, the DNA diagnosis is accurate, but the genetic heterogeneity of individual porphyrias restricts usefulness of this method. During an acute attack, symptoms include severe abdominal pain, vomiting, constipation, often pain in the extremities and in the back, and psychologic symptoms that range from anxiety to delirium. Urine may be dark or red in color because of increased amounts of porphobilin and porphyrins. Heme is much more effective in this regard than Specific treatment is justified only when a patient has symptoms and signs compatible with an acute attack and increased excretion of porphobilinogen in the urine. The presence of symptoms without raised levels of porphobilinogen, or the finding of raised levels of porphobilinogen, 5-aminolevulinic acid, or porphyrins without symptoms, is Symptomatic Therapy Patients with acute attacks usually have symptoms that may necessitate medication or other therapies.