Cortisol (Morning) Test

Why does timing matter so much for cortisol testing?

Cortisol follows a strong daily rhythm, naturally peaking in the morning and dropping to its lowest point at night, so results are only meaningful when interpreted against the expected time of day the sample was drawn.

Can stress before the test affect my result?

Yes, both physical and emotional stress can temporarily raise cortisol levels, so a calm, rested state before the blood draw helps ensure the most accurate result.

Is one abnormal cortisol test enough for a diagnosis?

Usually not — an abnormal result typically leads to additional, more specific tests (such as an ACTH stimulation test or dexamethasone suppression test) to confirm the diagnosis and pinpoint the underlying cause.