BACKGROUND: Patients experience preoperative anxiety which stimulates the release of catecholamines. They have influences on serum K⁺ level by shifting them into the intracellular space. The purpose of this study is to determine whether there is a correlation between anxiety and the serum potassium level immediately before induction of anesthesia.

METHODS: Thirty patients were asked about their anxiety levels at 7 : 00 pm of the day before surgery and immediately before induction of anesthesia : 0; nil, 1; slight, 2; moderate, 3; marked. At those times, arterial blood was taken for checking serum K⁺ level and blood gas analysis.

RESULTS: There was no significant correlation between anxiety level and serum potassium level. At 7 : 00 pm of the day before surgery, the anxiety levels of patients had no significant correlation with the changes of serum potassium level ("K₁-K₂"; K₁ = serum potassium level of patient at 7 : 00 pm of the day before surgery, K₂ = serum potassium level of patient immediately before induction of anesthesia). Definite correlation between the anxiety level immediately before induction of anesthesia and the changes of serum potassium level has been documented. Immediately before induction of anesthesia, 43% of patients had hypokalemia (K⁺ < 3.5 mEq/L).

CONCLUSIONS: Anxiety level has no correlation with serum potassium level, but the anxiety level immediately before induction of anesthesia has the changes of serum potassium level. If a patient has high anxiety level immediately before induction of anesthesia, the possibility of hypokalemia is increased.