[The role of melatonin in the immediate postoperative period in elderly patients]

Melatonin induces sleep and modulates immune system. Aim of the paper is to show a possible relation between impaired rhythm of melatonin secretion and the onset of postoperative septic complications and insomnia in old patients undergoing surgery.

Fifty old patients, aged from 60 to 94 years, have been studied; 39.5% of the patients had neoplastic disease. Melatonin serum levels have been evaluated by ELISA technique at 12 p.m., 3 a.m. 8 a.m. immediately before operation. Postoperative clinical findings of insomnia and septic complications have been recorded.

The melatonin serum mean values of all the patients were 16.3 pg/ml at 12 p.m., 22.4 pg/ml at 3 a.m. and 7.1 pg/ml at 8 a.m. Neoplastic patients showed the higher values of melatonin (26.696 pg/ml, 33.143 pg/ml, 9.185 pg/ml), long-lived patients (> 90 years) the lower. The melatonin secretion curve of the old patients with postoperative insomnia (19.961 pg/ml, 20.297 pg/ml, 9.378 pg/ml) or postoperative septic complications (20.695 pg/ml, 16.183 pg/ml, 6.036 pg/ml) was significantly different compared with that of other patients. The peak was advanced, lower and decreased slowly in the midnight.

The study seems to show a possible correlation between impaired rhythm of melatonin secretion and postoperative insomnia and postoperative sepsis in old patients undergoing surgery.