Diagnostic value of salivary cortisol in end stage renal disease

ObjectivesSalivary cortisol has been proposed a surrogate marker for free serum cortisol measurements. The aim of this study was to ascertain the diagnostic value of basal and stimulated salivary cortisol for the detection of adrenal insufficiency (AI) in hypotensive end stage renal disease (ESRD) patients. Basal salivary cortisol and basal total serum cortisol were studied in order to determine the accuracy of both biomarkers in predicting AI.Patients and methodsTwenty-nine ESRD patients with sustained hypotension were investigated for possible AI. Salivary cortisol was assessed at baseline and 30 min after 25 μg ACTH i.m. (LDTs). The dosage of salivary aldosterone was performed in salivary cortisol hypo-responders. Basal blood samples were drawn for steroids, renin and ACTH measurements.ResultsA clear separation between patients with normal and impaired adrenal function was obtained through salivary cortisol levels at 30 min after ACTH. AI was detected in six cases (21%) through impaired salivary cortisol responses; stimulated salivary aldosterone helped to differentiate primary (n = 3) from secondary AI (n = 3). ROC curves showed that cutoff values for basal SAF ≤4.4 nM and serum cortisol ≤232.0 nM suggest AI (sensitivities: 93% and 69%; specificities: 86.4% and 91%, respectively).ConclusionsWe conclude that ACTH stimulated SAF is an accurate biomarker for the diagnosis of AI in hypotensive ESRD patients. Neither basal salivary cortisol nor serum cortisol showed 100% sensitivities for the detection of AI.