Endocrine Abstracts

Introduction: Salivary cortisol measurement, representing free cortisol, seems to be a promissing alternative method to serum cortisol. Besides its use in the diagnostics of hypercortisolism, it could be of help in evaluation of adrenocortical reserve. It might be useful especially in patients on estrogen replacement, which modulates transcortin and hence total cortisol levels.

Aims: Compare the reliability of salivary vs. serum cortisol assessment during ACTH test.

Patients: We have performed ACTH test in 84 subjects (mean age 63.2; 66 men) with clinical suspicion on hypocorticism. According to the peak serum cortisol (≥500 nmol/l) patients were divided into two groups. Group A with normal response (n=76; mean age 64; 60 men) and group B with hypocorticism (n=8; mean age 61.4; six men).

Methods: 250 μg teracosactide was injected intravenously. The blood and saliva were obtained before, in 30 and 60 min afterwards.

Results: Medians of serum cortisol in group A were 445; 766 and 902 nmo/l in 0, 30, and 60 min and 256; 394; and 453 in group B respectively. Medians of salivary cortisol were 6.9; 14.5 and 22.5 nmol/l in group A and 3.5; 5.1 and 4.8 nmol/l in group B. There was a significant correlation between serum and salivary cortisol levels during the test. The percent of variability as an expression of discriminating power, explained by the repeated measures ANOVA model, was significantly (P=0.021) higher for serum cortisol (R²=93.4%) compared to salivary one (R²=89.3%).

Conclusion: Our data show significant correlation between salivary and serum cortisol levels during the ACTH test. Measurement of serum cortisol has superior discriminating power compared to salivary cortisol in standard evaluation of adrenocortical reserve not influenced by estrogen replacement.