Midnight Salivary tests are used in the diagnosis and screening of Cushing's syndrome or monitoring of cyclical Cushing's syndrome.
Collection is in a salivette ONLY.
FROM 31/09/2023 ONLY SAMPLES COLLECTED WITH SALIVETTE WILL BE ACCEPTED. PLEASE SEE SALIVETTE ORDERING DETAILS BELOW.
How to collect a saliva sample for a cortisol test:
• Do not brush or floss your teeth before collecting the sample.
• Do not eat or drink 30 minutes before collecting the sample.
• Do not use any creams or lotions that contain steroids such as hydrocortisone 30 minutes before collecting the sample.
A salivette is now the ONLY method of collection for this test.
To collect your sample using a salivette, 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.
The salivette must be sealed tightly and labelled with the name, date, time and any other instructions from the doctor.
Please ensure collection date and times are clearly labelled on samples to assist with interpretation.
Salivettes are available to purchase from Bio-strategy Limited using supplier item number 51.1534. For assistance in obtaining/purchasing salivettes please contact the lab.
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.
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.
Extraction followed by LC-MS/MS
$35.30 (Exclusive of GST)
For results please contact Canterbury Health Laboratories ph. 03 364 0300.
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