Long-Term Follow-up of Erythrocyte Porphobilinogen Deaminase Activity in a Patient With Acute Intermittent Porphyria: The Relationship between the Enzyme Activity and Abdominal Pain Attacks

The relationship between the onset of abdominal pain attack and the urinary levels of δ-aminolevulinic acid, porphobilinogen, uroporphyrin, and the activity of erythrocyte porphobilinogen deaminase was studied on a monthly basis over a four-year period in a 29-year-old male patient with acute intermittent porphyria. A close relationship is seen between the onset of pain episodes and sharp decreases of porphobilinogen deaminase activity. The activity normalizes as the patient improves, suggesting that this enzyme is a more sensitive monitor for acute intermittent porphyria attacks than the urinary parameters currently used for its diagnosis. Our results suggest that month-by-month testing of porphobilinogen deaminase activity in acute intermittent porphyria patients is a good practice to predict episodes of acute abdominal pain before its onset, also allowing estimation of possible promoting factors and in establishing optimal specific therapies.