ACUTE INTERMITTENT PORPHYRIA - A group of metabolic disorders that result from a disturbance in porphyrin metabolism, causing increased formation and excretion of porphyrin or its precursors. Acute intermittent porphyria is a rare inherited (autosomal dominant) form that can result in abdominal pain, photosensitivity, and neurological disturbances. The various forms can be differentiated measuring various blood porphyrins.