Endocrine Abstracts

Aim: If ‘0’minute salivary cortisol (SALCORT_0) or cortisone (SALCONE_0) can predict normal post-synacthen cortisol response.

Method: Baseline salivary sample was collected for 110 patients who had short synacthen test (SST) between 09:00 and 10:00 after hydrocortisone withdrawal for at least 24-hour. SST was labelled ‘pass’ if 30-minute serum cortisol was >450 nmol/l. Serum cortisol was measured by immunoassay whereas salivary cortisol and cortisone were measured by liquid-chromatography tandem mass-spectrometry.

Results: SALCORT_0 and SALCONE_0 were undetectable in 13 and 2% respectively. SALCORT_0:SALCONE_0 ratio was 5.1±3.4 nmol/l (1.2–20.6) in patients not on steroid (PNS; n=72, 8 ‘fail’ SSTs) and 4.4±2.2 nmol/l (0.09–9.83) in patients on hydrocortisone (POH; n=38, 8 ‘pass’ SSTs). Ratio<1.2 hinted saliva contamination by hydrocortisone, and both patients had ‘failed’ SST. In POH, SALCORT_0 and SALCONE_0 as high as 25.4 and 35.2 nmol/l were in ‘failed’ synacthen. As they were with CORT_0 of >300 nmol/l and flat SST, they are likely result of non-compliance with instruction to omit hydrocortisone before test. That a reason why they are not useful to predict ‘pass’ in SST. Lowest values of SALCORT_0 and SALCONE_0 amongst ‘pass’ SSTs in POH were 2.91 and 17.3 nmol/l respectively; and 13 of 38 patients had both values below these. In PNS; highest values of SALCORT_0 and SALCONE_0 in ‘failed’ synacthen were 4.07 nnol/l and 25.8 nmol/l respectively; and would preclude any predicting ability as no patient had both values above this.

Conclusion: SALCORT_0 and SALCONE_0 under cut-off could predict ‘failed’ SST in POH and it could be delayed till either value cross the cut-off and the ratio>1.2. 9am salivary sample collection at home would significantly alleviate logistic and financial implications of repeated SSTs in those with low pre-test probability of ‘pass’ and could have avoided 39% SSTs in our cohort.