Cortisol, often referred to as a stress hormone, plays a broad role in the body’s daily functions. This steroid hormone is a natural part of various physiological processes, including metabolism, immune responses, and maintaining blood pressure. Measuring cortisol levels in saliva offers a convenient method to assess its presence in the body.
The Body’s Cortisol System
Cortisol is a steroid hormone produced by the adrenal glands, which are small, triangular organs located on top of each kidney. It belongs to a class of hormones called glucocorticoids, which help reduce inflammation. The body’s production and release of cortisol are tightly regulated by a network known as the hypothalamic-pituitary-adrenal (HPA) axis.
When the body experiences stress, the hypothalamus releases corticotropin-releasing hormone (CRH), which signals the pituitary gland to release adrenocorticotropic hormone (ACTH). ACTH then travels to the adrenal glands, prompting them to produce and release cortisol. Cortisol helps the body respond to stress by mobilizing energy stores, increasing blood pressure and heart rate, and enhancing alertness. It also influences how the body uses glucose for energy and plays a role in modulating the immune system.
Advantages of Saliva Testing
Salivary cortisol measurement offers several benefits. The collection process is non-invasive and generally stress-free, beneficial for those with anxiety about blood draws. Its ease allows for multiple daily samples.
Collecting several samples enables a comprehensive assessment of the diurnal rhythm, or the natural daily pattern of cortisol secretion. Salivary tests measure “free” cortisol, the unbound, biologically active form of the hormone that is readily available to tissues. In contrast, blood tests typically measure total cortisol, which includes both free and protein-bound forms, and may not fully reflect the amount of cortisol acting on the body’s cells. While urine tests can also assess diurnal patterns and provide insights into cortisol metabolites, they represent a pooled average over hours, whereas saliva provides a snapshot of cortisol at a specific moment.
Interpreting Salivary Cortisol Results
Interpreting salivary cortisol levels involves observing their diurnal rhythm. Cortisol levels are highest in the morning, peaking within 30 minutes of waking, and gradually decline throughout the day, reaching their lowest point before bedtime (midnight to 4 AM). This characteristic pattern is important for assessing adrenal gland function.
Consistently elevated salivary cortisol, especially late at night, may suggest conditions such as chronic stress or hypercortisolism, which is often associated with Cushing’s syndrome. Symptoms linked to high cortisol can include rapid weight gain, a rounded face, high blood pressure, and muscle weakness. While stress can temporarily increase cortisol, persistently high levels often indicate an underlying health concern.
Conversely, consistently low salivary cortisol may indicate adrenal insufficiency (Addison’s disease). Symptoms associated with low cortisol can include chronic fatigue, muscle weakness, low blood pressure, and unexplained weight loss. Both persistently high and low cortisol levels can have significant health implications, and any abnormal results should be discussed with a healthcare professional to determine the underlying cause and appropriate course of action.
Influences on Salivary Cortisol Readings
Various factors can influence salivary cortisol readings, making accurate collection and interpretation important. Acute stress (e.g., physical activity or emotional challenges) can cause temporary cortisol spikes. Insufficient sleep can also affect the natural diurnal rhythm.
Certain medications, particularly corticosteroids, directly impact cortisol levels and should be disclosed before testing. For accurate results, avoid eating, drinking, or brushing teeth for at least 30 minutes before collecting a sample. Gum bleeding can also lead to high readings due to blood contamination. Following specific collection instructions, such as using the provided swab and collecting at recommended times, helps ensure reliable results.