Increased plasma nitric oxide metabolites in suicide attempters

Objective: To evaluate any correlation between plasma levels of nitric oxide metabolites (NO_x) and suicide attempt. Method: Plasma NO _x levels were measured in 53 patients who had recently attempted suicide, 58 nonsuicidal psychiatric patients, and 75 normal controls. The severity of suicidal behaviors was evaluated using Weisman and Worden's Risk-Rescue Rating Scale. Results: Plasma NO_x levels were significantly higher in suicidal patients than nonsuicidal psychiatric patients or normal control subjects (F = 11.029, d.f. = 2, 183, p < 0.001). Among the patients with a diagnosis of major depression, suicidal depressive patients had significantly higher plasma NO_x levels than nonsuicidal depressive patients (t = -3.090, d.f. = 84, p = 0.003). Conclusion: Our study suggests that increased NO production in plasma is associated with suicide attempt, especially in depressive patients.