ZRT Cortisol Awakening Response - CAR

The Cortisol Awakening Response—also called CAR—is an at-home hormone test panel. CAR reveals more detailed clues that help in assessing adrenal gland function and conditions related to abnormal cortisol levels. Here are some symptoms and conditions that might prompt such a test:

Collecting saliva samples six times in a 24-hour period, especially with the first three samples collected in the morning, helps in charting the diurnal (daytime) variation in cortisol levels. This can provide valuable information about the adrenal glands' function and the body's stress response. Samples are collected at home in the test kit provided, returned, and analyzed in a CLIA-certified lab. 

• Suspected Adrenal Fatigue or Dysfunction: If a person is experiencing symptoms such as chronic tiredness, fatigue, muscle weakness, and unexplained weight loss, a practitioner might suspect adrenal insufficiency or fatigue. Testing cortisol levels may help in a determination of possible causes.

• Cushing's Syndrome: This is a condition caused by high cortisol levels for a prolonged period. Symptoms include weight gain, particularly around the abdomen and face; a flushed and round face; high blood pressure; osteoporosis; and changes in skin condition (like bruising easily and purple stretch marks).

• Addison's Disease: This is the opposite of Cushing's syndrome and is characterized by too little cortisol. Symptoms can include fatigue, muscle weakness, weight loss, low blood pressure, and darkening of the skin in certain areas.

• Chronic Stress: Chronic stress can lead to dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, affecting cortisol levels. Symptoms might include fatigue, anxiety, depression, and irritability.

• Sleep Disorders: Abnormal cortisol levels can affect sleep patterns. Testing cortisol may help any individual who is having difficulty sleeping or feels not rested after sleep.

• Evaluating the Diurnal Cortisol Curve: Normal cortisol levels vary throughout the day. They are usually higher in the morning upon waking and decrease throughout the day. Abnormal patterns, such as flat curves or levels that are high at night, can suggest health issues.

Cortisol Awakening Response Sample Collection

6-Tube Saliva Collection: Six cortisol collections in 24 hours is the most common method for assessing CAR. Start saliva collection within five minutes of waking for the day, followed by a second sample at 30 minutes and a third sample at 60 minutes. The rest of the diurnal rhythm can be assessed at the normal time intervals—noon, evening, and night. Click here for more collection instructions.