TY - JOUR T1 - MHpg excretion AU - Rifkin A, Quitkin F Y1 - 1979/08/01 N1 - 10.1001/archpsyc.1979.01780090116013 JO - Archives of General Psychiatry SP - 1030 EP - 1030 VL - 36 IS - 9 N2 - To the Editor.—  The article by Pickar et al (Archives 35:1378-1383, 1978) on the relationship of changes in excretion of 3-methoxy-4-hydroxyphenethylene glycol (MHPG) and remission of depressive symptoms at the time of follow-up requires a cautionary note. The most important finding was that the ratio of follow-up-baseline levels of MHPG was higher in the six patients whose conditions were in remission than in the four whose conditions were not.The difficulty in interpreting this is that a variable known to affect outcome was not controlled: treatment with drugs. Three of the six patients whose conditions were improved had been receiving drugs before the 21day drug-free period prior to evaluation. Only one of the four whose conditions did not improve had received drugs. In the absence of a prospective study, holding known relevant variables constant, we cannot conclude that the finding by these authors is unambiguous. It may very well be true SN - 0003-990X M3 - doi: 10.1001/archpsyc.1979.01780090116013 UR - http://dx.doi.org/10.1001/archpsyc.1979.01780090116013 ER -