Salivary Cortisol and Cortisone After Low-Dose Corticotropin Stimulation in the Diagnosis of Adrenal Insufficiency.

CONTEXT: Basal and poststimulation salivary cortisol and cortisone levels can be useful in the diagnosis of adrenal insufficiency. However, little is known about the optimal cutoffs and performance characteristics of these tests. OBJECTIVE: To derive the cutoff values and study the performance characteristics of salivary cortisol and salivary cortisone in the diagnosis of adrenal insufficiency. DESIGN AND SETTING: Prospective study in a regional hospital in Hong Kong from January 2014 to September 2015. PARTICIPANTS: Fifty-six Chinese healthy volunteers and 171 patients suspected of having adrenal insufficiency. MAIN OUTCOME MEASURES: All participants underwent low-dose short Synacthen test (LDSST) with intravenous injection of 1 µg of tetracosactide (Synacthen 1-24). Serum cortisol, salivary cortisol and cortisone levels were measured at baseline and 30 and 60 minutes afterward. RESULTS: Using the reference cutoff (mean - 2 standard deviations of post-LDSST peak serum cortisol) derived from healthy volunteers as the gold standard, receiver operating characteristic analysis of patients' data revealed that both post-LDSST peak salivary cortisol and cortisone performed better than basal tests. The most optimal cutoff values for serum cortisol as measured by immunoassay and for salivary cortisol and salivary cortisone as measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS) were 376, 8.6, and 33.5 nmol/L, respectively, for post-LDSST peak values, and 170, 1.7, and 12.5 nmol/L, respectively, for basal values. CONCLUSIONS: We established method-specific reference cutoffs for serum cortisol, salivary cortisol, and salivary cortisone during LDSST. Both post-LDSST peak salivary cortisol and cortisone performed well as diagnostic tests for adrenal insufficiency. Their measurements by LC-MS/MS can alleviate problems associated with serum cortisol immunoassays.

The use of aldosterone-renin ratio as a diagnostic test for primary hyperaldosteronism and its test characteristics under different conditions of blood sampling.

Recent reviews recommended the use of the aldosterone/renin ratio (ARR) to screen for primary hyperaldosteronism. However, widely different cutoff levels have been proposed, and test characteristics of ARR under different conditions of sampling are not known. We conducted a retrospective review among 45 subjects with carefully validated diagnoses of primary hyperaldosteronism and 17 subjects with essential hypertension to study the utility of ARR. Sixty-two patients with 75 sets of plasma renin activity (PRA), aldosterone, and ARR values from a postural study and 48 sets of values from a saline suppression test were analyzed. Ninety-four percent of these subjects underwent investigations because of hypokalemic hypertension.ARR yielded larger areas under the curve in the receiver-operating-characteristics curve than PRA or aldosterone under all conditions of testing. Our results confirmed the superiority of ARR to either aldosterone or PRA alone as a diagnostic test for primary hyperaldosteronism.ARR cutoff levels were significantly affected by the condition of testing. Depending on posture and time of day, it varied from 13.1-35.0 ng/dl per ng/ml.h in our study population. When using ARR for screening primary hyperaldosteronism, posture and time of sampling should be standardized both within and between centers to minimize variability in cutoff levels.