[EEG changes in a patient with acute intermittent porphyria and a Schwartz-Bartter syndrome (SIADH)].

A 24-year-old female with gastrointestinal disturbances, nausea and vomiting, had a convulsion with loss of urine and bitten lips on the 5th day of hospitalization. A significant decrease of sodium and potassium levels and lowered osmolality of the serum as well as urinary hyperosmolality permitted the diagnosis of the so-called syndrome of inappropriate antidiuretic hormone release (SIADH) of unknown aetiology, described by Schwartz-Bartter. Twice short tests for porphyria were negative; then the elevated porphyrin precursors collected in 24 h urine indicated the existence of an acute intermittent porphyria. A clinical follow-up and improvement were demonstrated by the EEG findings. Since animal experiments and pathohistological findings indicate that porphyrin metabolites such as delta-amino laevulinic acid and porphobilinogen may influence inhibitory and neurosecretory structures in central nervous tissue and interfere with GABA, cerebral hyperexcitability as well as disturbance of electrolytes may be explained. Finally, the question of whether the EEG changes are due to the significant electrolyte disturbances or are typical signs of acute intermittent porphyria is discussed.