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ZRT Laboratory

Diurnal Cortisol 4x

Diurnal Cortisol 4x

The Diurnal Coritsol test is four saliva collections on a single day – typically done upon waking, before lunch, dinner, and before bed. The labs then report them on a 24-hour graph. The resulting curve – also called a four-point cortisol curve or circadian cortisol pattern, allows healthcare providers to assess the hypothalamic-pituitary-adrenal axis (HPA axis) or adrenal dysfunction.

Cortisol that does not follow the normal pattern can trigger blood sugar imbalances, fatigue, insomnia, food cravings, and weight gain. Related imbalances of low DHEA commonly result in loss of lean muscle, lack of strength, decreased stamina, and low exercise tolerance.

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Cortisol: Cortisol is a stress hormone produced by the adrenal glands that plays a critical role in the body's stress response and regulation of metabolism, immune function, and energy levels. Dysregulation of cortisol levels can lead to adrenal dysfunction and contribute to symptoms such as fatigue, insomnia, and mood disturbances [16.]. By testing salivary levels of cortisol at 4 time points in a 24 hour period, this test maps out the individual’s diurnal cortisol rhythm and may provide insight into chronic stress, sleep disturbances, immune or digestive dysfunction, and more. [1.]

Basic Instructions

Saliva collection involves collecting samples at specific times and using provided tubes to pool saliva.

Saliva should be collected in the morning upon waking (8am), before lunch (12pm), before dinner (6pm), and before bed (10pm).


+ Cortisol (morning)
+ Cortisol (noon)
+ Cortisol (evening)
+ Cortisol (night)

For Those Who Experience...

+ Stress
+ Immune dysfunction
+ Chronic fatigue
+ Multiple symptoms of adrenal imbalance