Cortisol elevation and serum gamma-glutamyl transpeptidase in response to adverse job conditions: how are they interrelated?

This study explores the use of plasma cortisol as an indicator of psychologically straining work. As plasma cortisol and liver function might be associated through biological mechanisms, this paper has a secondary object, namely to explore the interaction between cortisol and liver function. As an index of liver function the serum level of gamma-glutamyl transpeptidase (GT) was used. The study sample was 2,000 prison employees from 67 different prisons in Sweden. Questionnaires and health examinations were used as well as measurements of plasma cortisol and serum GT. Very few work-related factors were associated with plasma cortisol unless analyzed separately for high and low level of serum GT. Two-way analyses of variance showed significant differences in the physiological "responses" to straining work with regard to psychic strain at work (men), social support at work (men), job role (men), loneliness at work (men and women), management style (women) and overtime work (women) between "low serum GT" and "high serum GT" individuals. Aggregated analyses showed that prison means of work-related factors were in some respects associated with prison means of plasma cortisol. The conclusion is that in individually based analyses plasma cortisol is difficult to use as an indicator of straining work, especially if the level of serum GT is unknown.