Change in circadian cortisol rhythmicity in patients with intracranial tumour

To verify the influence of intracranial expanding processes on circadian cortisol rhythm, we studied its occurrence in 10 normal subjects, in 5 patients with extrasellar tumour, and in 3 patients with intracranial haematoma. All patients were tested every 4 h. Cortisol was measured by RIA. A cosine function was fitted to the data by mean cosinor method to evidence any rhythm and its parameters. A significant circadian rhythm was detected in the normal subjects with acrophase at 07.55 (07.15-08.25). The patients with extrasellar tumour and those with intracranial haematoma showed a lack of circadian rhythmicity due to a significant increase of cortisol levels at 20.00 and at 00.00, respectively. Our results suggest that study of the cortisol rhythm is useful, especially when an extrasellar tumour is suspected.