Diagnosis of Cushing syndrome in patients presenting with symptoms or signs suggestive of the disease
Specimen Type
Saliva
Specimen Requirements
Cortisol, Saliva Collection Kit (T514)
Specimen Collection / Processing Instructions
Patient Preparation:
Do not brush teeth before collecting specimen
Do not eat or drink for 15 minutes prior to specimen collection
Supplies: Cortisol, Saliva Collection Kit (T514)
Container/Tube: SARSTEDT Salivette
Specimen Volume: 1.5 mL
Collection Instructions:
Provide patient with a Saliva Collection Kit (Salivette) containing the Cortisol – Saliva Collection Instructions and ask them to follow the instructions as written
Instruct patient to collect specimen between 11 p.m. and midnight and record collection time on the Cortisol - Saliva Collection Instructions sheet
Instruct patient to return Cortisol - Saliva Collection Instructions with the appropriately labeled Salivette to the laboratory
Additional Information:
Reference values are also available for an 8 a.m. (7 a.m.-9 a.m.) or a 4 p.m. (3 p.m.-5 p.m.) collection, however, the 11 p.m. to midnight collection is preferred
If multiple specimens are collected, submit each vial under a separate order
Minimum Sample Volume
0.6 mL
Required Information
Collection time is required
Stability
Refrigerated (preferred): 28 days
Frozen: 60 days
Ambient: 28 days
Unacceptable Specimen Conditions
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability
Limitations
Acute stress (including hospitalization and surgery), alcoholism, depression, and many drugs (eg, exogenous glucocorticoids, anticonvulsants) can obliterate normal diurnal variation, affect response to suppression/stimulation tests, and cause elevated cortisol levels
Cortisol levels may be increased in pregnancy and with exogenous estrogens
Midnight salivary cortisol assay cannot diagnose hypocortisolism or Addison disease because of the limited sensitivity of the assay method
Methodology
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
