[Propofol pharmacokinetics in a patient with TSH producing pituitary adenoma]

We investigated propofol pharmacokinetics in a patient with secondary hyperthyroidism caused by thyroid stimulating hormone (TSH) producing pituitary adenoma. Laboratory data indicated thyrotoxic state with elevated TSH, FT3 and FT4 levels. General anesthesia was maintained with a doubled propofol infusion rate (8-10 mg.kg-1.hr-1) compared to our standard procedure. During 370 min of infusion, propofol concentrations in arterial blood were kept within optimal ranges (2-4 micrograms.ml-1). Although the clearance of propofol was high (2.8 l.min-1) because of the thyrotoxic state, the patient showed delayed recovery from anesthesia. The half-life of blood propofol after the termination of infusion exceeded 30 minutes (normal: 10-15 minutes). We conclude that the delayed recovery was due to the accumulation of propofol in the adipose tissue during long-term infusion in spite of the increased propofol clearance.