Acute intermittent porphyria: a diagnostic challenge.

Acute intermittent porphyria is a metabolic disorder rarely seen in prepubertal children. A delay in diagnosis of acute intermittent porphyria is common because of variable and nonspecific symptoms. We report an 8-year-old boy with right hemimegalencephaly and intractable seizures, who presented with dark-colored urine, hypertension, increasing lethargy, fluctuating seizures, and poor oral intake. He subsequently developed hyponatremia secondary to syndrome of inappropriate antidiuretic hormone secretion. His urinalysis was negative for red blood cells, and a random urine porphobilinogen level was elevated. Further biochemical and molecular testing confirmed the diagnosis of acute intermittent porphyria. His antiepileptic medications were discontinued and hemin administered, with dramatic clinical improvement. The diagnosis of acute intermittent porphyria was challenging because of his underlying neurologic condition. This case highlights the variable presentation of acute intermittent porphyria and emphasizes the importance of considering the diagnosis even in young patients with underlying neurologic conditions when they present with nonspecific neurovisceral symptoms or with unexplained neurologic deterioration.