Melatonin secretion in patients with pineal region tumors-preliminary report

Tumors of the pineal region, though not very common, are recently more often diagnosed due to the introduction of computer tomography and magnetic resonance examinations into neurosurgical practice. However many controversies about the treatment of them still exist. Some of them need aggressive treatment. The others are benign and asymptomatic. Thus it seems to be important to improve our diagnosis of mass lesion of the pineal region, especially before taking a decision for surgery. The purpose of this study was to find any significant changes in the circadian pattern of melatonin secretion in patients with pineal region tumors. Blood samples were collected preoperatively from 21 patients with diagnosed pineal region tumors. In 13 patients sampling was performed at 08:00, 14:00, 20:00 and 02:00 h during a 24-hour period but in 8 former ones only at 02:00 h at night. The samples were immediately centrifuged and the serum stored at -20 degrees C until analysis. The patients stayed in the darkened room from 23:00 to 05:00 h. Plasma melatonin was measured by direct and specific radioimmunoassay. The following three groups of results were found: (1) eight patients showed normal melatonin secretion profiles, (2) six cases with lack of the night maximum plasma value, and (3) seven cases with nocturnal melatonin concentration higher than in the healthy population (>100pg/ml). We observed no correlation between melatonin secretion and histological type of tumor. In conclusion, we suggest that changes of melatonin secretion could indicate the pineal region pathology. However further studies with a larger group of patients, especially with tumors originating from the pineal gland (pinealocytoma, pinealoblastoma), are necessary.