[Morning changes in the sigma ESR, erythrocyte sedimentation rate (Westergren) and C-reactive protein]

A comparative study of the morning variation of the Sigma and Westergren sedimentation rates, and C-reactive protein was undertaken in 90 patients with osteoarticular disease (measurements at 07:00, 09:00, 10:00, and 12:00). The mean values of all three tests were elevated at 07:00 in patients with inflammatory disease, and no significant variation was observed in the Westergren sedimentation rate or C-reactive protein throughout the morning, irregardless of whether an anti-inflammatory agent was used. On the other hand, there was a very significant increase in the Sigma sedimentation rate at 09:00 in untreated patients (p less than 0.0001, n = 24). This morning increase of the Sigma sedimentation rate was not related to food intake, identical value being obtained in fasting or postprandial samples from the same patients. The Sigma sedimentation rate at 09:00 was significantly reduced however, in patients treated with an effective level of an anti-inflammatory agent (p less than 0.001, n = 32). This decrease varied in size and duration depending on the anti-inflammatory agent used. The existence of a circadian rhythm of the Sigma sedimentation rate which can be reversed with anti-inflammatory drug usage is helpful in understanding the chronobiologic aspects of the inflammatory process. Numerous therapeutic applications can be foreseen.