A Preliminary Study of Circadian Serum Cortisol Concentrations in Response to a 72-hour Fast in Rheumatoid Arthritis Patients not Previously Treated with Corticosteroids

Abstract

The aim of the study was to investigate the effects a 72-h fast upon serum total and free cortisol concentrations in RA patients not previously treated with glucocorticoids. Total serum cortisol and transcortin concentrations were measured in four RA patients with active disease at 4-h intervals during two 24-h periods (1200 h-1200 h), the first while eating a normal diet (fed state) and the second during the last 24 h of a 72-h water fast. Free cortisol concentrations were calculated from the total cortisol and transcortin values. The 3-day fast increased overall 24-h free and total cortisol concentrations by 50% and 35%, respectively. This was due largely to a marked increase in nocturnal serum cortisol concentrations during fasting, particularly at 0400 h, when mean total and free cortisol levels were increased by 170% and 260% compared to the fed state. Between 2000 and 0800 h overall total- and free cortisol concentrations were increased by 72% and 99%, respectively. These results suggest that an increase in nocturnal concentrations of cortisol occurs in response to fasting in RA patients not previously treated with glucocorticoids. These increases may mediate the beneficial clinical response previously found in studies of longer fasting periods in RA patients.