A new concept for melatonin deficit: On pineal calcification and melatoninexcretion.

Even though exogenous melatonin has proven to influence sleep and circadian parameters, low endogenous melatonin is not related to sleep disturbances, nor does it predict response to melatonin replacement therapy. In this man uscript, we present a new concept towards a definition of a melatonin defic it. The purpose of the study was to introduce a marker for an intra-individ ual decrease in melatonin production. Therefore, we developed a method to q uantify the degree of pineal calcification (DOC) using cranial computed tom ography. combining pineal DOC with the organs's size, we estimated the unca lcified pineal gland volume. This estimation was positively and significant ly associated wit 6-sulfatoxymelatonin (aMT6s), collected over 24 hours in urine, in 26 subjects. Data yielded evidence that the decline in aMT6s excr etion with age can be sufficiently explained by an increased pineal calcifi cation. These results suggest that DOC might be useful as an indicator of a n intra-individual, decreased capability of the pineal gland to produce mel atonin. DOC might prove to be a response-marker for melatonin replacement t herapy and a vulnerability marker of the circadian timing system. [Neuropsy chopharmacology 21:765-772, 1999] (C) 1999 American College of Neuropsychop harmacology. Published by Elsevier Science Inc.