• To screen for cortisol excess (Cushing syndrome) using first-line tests such as late-night salivary cortisol, 1-mg overnight dexamethasone suppression, or 24-hour urinary free cortisol. Abnormal screens require endocrine follow-up. (endocrine.org)
• To assess possible adrenal insufficiency (cortisol under-production): morning serum cortisol helps initial evaluation; confirmation typically uses an ACTH (short Synacthen) stimulation test when clinically appropriate. (endocrine.org)

• To screen for cortisol excess (Cushing syndrome) using first-line tests such as late-night salivary cortisol, 1-mg overnight dexamethasone suppression, or 24-hour urinary free cortisol. Abnormal screens require endocrine follow-up. (endocrine.org)
• To assess possible adrenal insufficiency (cortisol under-production): morning serum cortisol helps initial evaluation; confirmation typically uses an ACTH (short Synacthen) stimulation test when clinically appropriate. (endocrine.org)

• Lower-than-expected morning cortisol can suggest adrenal insufficiency in the right clinical context, often requiring confirmatory dynamic testing. (endocrine.org)
• Elevated late-night salivary cortisol supports cortisol excess and is convenient for at-home screening. (endocrine.org)
• Results are assay- and lab-specific and must be interpreted by a clinician alongside symptoms, medications, and comorbidities. (MedlinePlus)

• Blood (serum, early morning): useful in under-function workups; additional testing is often needed for diagnosis. (endocrine.org)
• Saliva (late night, typically 11 pm–midnight): collect on two separate nights; avoid eating, smoking, brushing teeth immediately before; do not test if acutely unwell. (leaflets.ekhuft.nhs.uk)
• Urine (24-hour urinary free cortisol): accepted screening option for suspected cortisol excess. Fasting is not required for these screening tests unless your lab specifies otherwise. (endocrine.org)

ACTH, electrolytes (Na⁺/K⁺), ± DHEA-S; in suspected excess, consider overnight dexamethasone suppression and/or repeat late-night saliva and 24-h urine per guideline pathways; in suspected deficiency, consider ACTH stimulation testing. (endocrine.org)

Acute illness, sleep disruption, pregnancy, and medications (exogenous glucocorticoids, some estrogen therapies) can affect measurements. Oral estrogens raise cortisol-binding globulin and can increase total serum cortisol; salivary cortisol is less affected by binding proteins and may circumvent this issue. Follow your lab’s instructions (e.g., avoid black liquorice; check steroid creams/inhalers). (endocrine-abstracts.org)

• Endocrine Society — Diagnosis of Cushing’s Syndrome (first-line screening tests). (endocrine.org)
• Endocrine Society — Primary Adrenal Insufficiency (morning cortisol/ACTH and short corticotropin test). (endocrine.org)
• MedlinePlus — Cortisol Test (blood, saliva, urine overview). (MedlinePlus)
• NHS patient leaflets — Late-night salivary cortisol (timing/prep). (leaflets.ekhuft.nhs.uk)
• Endocrine abstracts & reviews on estrogen/CBG effects and the utility of salivary cortisol. (endocrine-abstracts.org)

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