Analysis of cortisol in saliva, a non-invasive tool for measuring endogenous cortisol production
The Spanish Society of Laboratory Medicine (SEQC-ML) holds a course on the measurement of cortisol in saliva, as part of its virtual training project SEQC-ML ACADEMY
• Experts in Biochemistry and Endocrinology presented saliva analysis as a diagnostic test that the patient can easily repeat at home, free of the stress resulting from collecting other fluids.
• Cortisol measurement is performed for the treatment and monitoring of diseases or disorders related to dysfunction of the hypothalamic-pituitary-adrenal axis; a key axis in the control of hemodynamic cardiovascular function and the general response to stress, both physiological and pathological.
Madrid, February 14, 2023 – The analysis of blood components has been one of the key pillars in the diagnostic procedures carried out by laboratories. However, other biological fluids have also been used frequently in laboratory diagnosis, such as urine and saliva. In particular, saliva is a fluid that offers a series of advantages over others in measuring cortisol (a hormone produced by the adrenal glands that helps the body cope with stress), as it is a non-invasive method for diagnosing alterations in the secretion and circadian rhythm of cortisol. This was one of the key issues addressed by experts participating in the course "New aspects to take into account in the measurement of cortisol in saliva", organized by the Spanish Society of Laboratory Medicine (SEQCML ) within the framework of its virtual training project SEQCML ACADEMY.
During the event, the head of the Endocrinology service at the Hospital Clínic de Barcelona, Dr. Felicia Hanzu, explained, in her presentation "What does cortisol in saliva contribute to clinical practice?", the importance of having a non-invasive test that the patient can easily repeat at home, "while also being an economical and reproducible test, which is key to establishing a diagnosis in endocrine diseases related to hypersecretion or hyposecretion of cortisol".
In addition, Dr. Hanzu highlighted the virtues of measuring cortisol in saliva compared to the use of other biological fluids. This tool, she argued, does not cause any type of stress for the patient due to the collection method, as opposed to "venipuncture when an analytical test has to be done, or when urine has to be collected over 24 hours".
The collection of the saliva sample for cortisol determination is usually carried out by the patient at home. In this way, as explained by Dr. Gregori Casals, member of the SEQCML Hormones Commission, "it is very important to transmit adequate information on the method and conditions of collection, including the schedule and preservation of the sample. Saliva is usually collected with the help of a device that includes a cotton swab that is "soaked" in saliva. According to Dr. Casals, in the laboratory this device is centrifuged to obtain the saliva sample to be analyzed. “The determination can be carried out in laboratories in an automated way by means of chemiluminescent immunoassays, usually the same ones used for serum samples, among other methods”, Dr. Casals noted.
In his presentation, "Analytical considerations for the adoption of salivary cortisol", Dr. Casals highlighted the importance of verifying that the method presents adequate quantification limits for clinical applications, due to the low concentrations of cortisol in saliva, especially in samples collected at night. Dr. Casals also stressed the importance of “checking that the method is prepared or shows good behavior in the saliva matrix, which is unusual in routine hormonal determinations. The effect that contamination of saliva with blood may have should also be taken into account and those results with macroscopically visible blood should be ruled out”.
Currently, the measurement of cortisol in saliva is a test incorporated into various clinical guidelines. In the words of Dr. Casals, the forecast is for it to be consolidated as a "common test in hormone laboratories for exploration of the adrenal axis as a complement to those tests that already exist." According to the expert, the convenience of the collection can facilitate more frequent monitoring, especially after the introduction of or changes in treatment. “In addition to the field of endocrinology, its possible usefulness in monitoring the degree of stress in children and adults is a matter of interest”, he added.