Cortisol, Saliva

Diagnostic Use

The midnight salivary cortisol test is used in the diagnosis and screening of Cushing's syndrome or the monitoring of cyclical Cushing's syndrome.
Multiple collections over 2-3 nights is recommended.

Department

Endocrinology Lab

Delphic Registration Code

SALC

Laboratory Handling

Phlebotomy

Collection is now in a salivette ONLY. See ordering and collection details below.

Synonyms

Salivary Cortisol

Turnaround Time

14 days

Test Code

03209

Specimen Type

• Saliva

Specimen Requirements

Tube/Container Type:

Preferred

• Please refer to Additional Information below

Preferred Sample Volume (ml)

0.5

Additional Specimen Information

ONLY SAMPLES COLLECTED WITH A SALIVETTE WILL BE ACCEPTED. PLEASE SEE SALIVETTE ORDERING DETAILS BELOW.

How to collect a saliva sample for a cortisol test:
• Do not brush your teeth or eat or drink for at least 60 mins prior to collection.
• Do not use any creams or lotions that contain steroids, such as hydrocortisone, for at least 60 mins prior to collection.
• Rinse mouth with water 10 mins prior to collection.
• Place swab in your mouth e.g. in your cheek where it should remain for two minutes without chewing. If an extremely small amount of saliva is produced, leave the
swab in the mouth for longer.
• Return roll (swab) to salivette, seal tightly and label with your name, date, time and any other instructions from the doctor.
• Store samples in a refrigerator immediately after collection and keep chilled until further processing at the laboratory.

Aliquot Instructions

Transport to Lab

Chilled (2 - 8 degrees Celsius)
Frozen

Additional Referral/Aliquot Information

Please ensure the collection date and times are clearly labelled on the sample to assist with interpretation.

Salivettes are available to purchase from Bio-Strategy Limited using supplier item number 51.1534 (Sarstedt). For assistance in obtaining/purchasing salivettes, please contact the lab.

Interpretation

Salivary cortisol is an ultrafiltrate of plasma and is not affected by protein binding and therefore reflects free cortisol. In states of altered cortisol binding, salivary cortisol (and cortisone) are more accurate measures of adrenal reserve than serum cortisol.

Cushing’s syndrome is a disorder of over-production of cortisol. Once exogenous cortisol from glucocorticoid drugs is excluded, the screening tests for Cushing’s syndrome include: midnight salivary cortisol, 24-hour urine free cortisol and overnight dexamethasone suppression test.

Reference Intervals

A midnight salivary cortisol of <4 nmol/L is not suggestive of Cushing’s syndrome, although the result should be interpreted in the clinical context.

A midnight salivary cortisol over > 4 nmol/L is considered to be a positive screening test for Cushing’s syndrome and warrants further investigation.

A markedly elevated salivary cortisol (>20 nmol/L) however salivary cortisone within normal range (<14 nmol/L) suggests contamination with topical or oral hydrocortisone.

Test Method

Extraction followed by LC-MS/MS

Non-Funded Test Cost

$36.89 (Exclusive of GST)

Contact Information

Enquiry Form