Excretion of 3-methoxy-4-hydroxyphenylglycol in depressed and geriatric patients and normal persons.

Measurement of urinary excretion of 3-methoxy-4-hydroxyphenylglycol (MHPG) is being tested in a number of psychiatric problems, most notably affective disorders. These measurements have certain problems. First, the collection of 24-hour urine specimens continues to be somewhat difficult, and no suitable solution has been found for using collections that might be incomplete. Second, the range of excretion of MHPG is rather similar in normal persons, depressed patients, and geriatric patients. One can think of no situation in all of medicine where diagnostic or prognostic distinctions can be made on the basis of variations within the normal limits of a laboratory test. Third, the variability of MHPG excretion may be high in some patients, even over the short term, clouding the significance of mean values of repeated determinations.