To the Editor.—
With reference to the article entitled "Receptor Sensitivity and the Mechanism of Action of Antidepressant Treatment" by Charney et al (Archives 1981;38:1160-1180), we disagree with the authors concerning our study on pretreatment urinary levels of 3-methoxy-4-hydroxyphenethyleneglycol (MHPG) as predictors of response to amitriptyline hydrochloride treatment. They stated that our results were nonconfirmative, but we actually did find significant differences between the responders to amitriptyline treatment (higher levels of MHPG) and the nonresponders (lower levels of MHPG).1 Our findings confirmed previous reports by Schildkraut2 and Beckman and Goodwin.3