Free Cortisol refers to the unbound, biologically active form of cortisol circulating in the body. Unlike total cortisol, which includes both bound and unbound hormone, free cortisol represents the fraction that is available to tissues and can directly influence stress response, metabolism, immune function, and energy levels. Measuring free cortisol provides a more accurate reflection of how the body is responding to physical and emotional stress. It is commonly assessed in urine or saliva samples and is particularly relevant in evaluating adrenal function and circadian rhythm imbalances.
Individuals experiencing chronic stress, fatigue, anxiety, or symptoms of adrenal dysfunction would benefit from cortisol testing. It’s also helpful for those with irregular sleep patterns, weight changes, or ongoing health issues linked to stress.
High Cortisol:
Low Cortisol:
Saliva testing for cortisol measures free, active hormone levels, reflecting the body’s immediate response to stress. Blood tests measure total cortisol, including both bound and unbound cortisol, giving a broader view of adrenal function over time.
Cortisol levels fluctuate throughout the day, peaking in the morning and gradually declining. Measuring several times captures this natural rhythm, providing a more accurate assessment of adrenal function and stress response.