Question 1

Purpose Test

Accepted Answer

Detecting loss of normal diurnal cortisol rhythm: A hallmark of Cushing’s syndrome, where cortisol fails to decrease adequately in the evening. Use in the dexamethasone suppression test: After an evening dose of dexamethasone, evening cortisol is measured. Persistent elevation supports Cushing’s diagnosis. Assessing the full HPA axis: Useful for evaluating the hypothalamic-pituitary-adrenal axis when rhythm disorders are suspected. Monitoring effects of chronic stress: Severe chronic stress can alter normal cortisol patterns; evening measurement helps detect this impact.

Question 2

Recommended groups

Accepted Answer

Patients suspected of Cushing’s syndrome, especially those with elevated or borderline morning cortisol. Patients showing clinical signs of cortisol excess, such as central obesity, moon face, or high blood pressure. Patients with known pituitary or adrenal tumors. Occasionally, it is used to assess sleep disturbances related to chronic psychological stress.

Question 3

Symptoms indicative

Accepted Answer

Cushing’s syndrome symptoms: weight gain in the trunk, rounded face, muscle weakness, high blood pressure. Sleep difficulties (insomnia) associated with chronic anxiety or stress. Need for comprehensive medical evaluation of a suspected hormonal disorder.

Question 4

Frequently Asked Questions (FAQs)

Accepted Answer

What is the normal evening cortisol level? The normal range varies, but it is usually less than 50% of the morning value. More specifically, it is often below 3-7 micrograms per deciliter (µg/dL) or 83-193 nanomoles per liter (nmol/L) by 10 PM. A level above 1.8 µg/dL (50 nmol/L) at midnight is considered abnormal and indicates loss of normal suppression. Why is this test requested along with the morning measurement? Diagnosis depends on the secretion pattern, not a single reading. In Cushing’s syndrome: Morning cortisol may be elevated or normal. Evening/night cortisol is abnormally high because it fails to decrease. Comparing the two readings reveals the disruption in the daily rhythm. Can my sleep pattern affect this test result? Yes, significantly. If you work night shifts and sleep during the day, your daily cortisol rhythm is reversed. In this case, cortisol may be naturally high in your “evening” (your wake time). Therefore, it is very important to inform your doctor if you have an irregular sleep schedule. The sample should be taken at your personal “evening” time.

Question 5

Normal Levels

Accepted Answer

Evening (4-6 PM): approximately 3-10 micrograms per deciliter (µg/dL). Midnight (10 PM - 12 AM): < 1.8 micrograms per deciliter (µg/dL) or < 50 nanomoles per liter (nmol/L) is the important cutoff. Normal (low) evening: indicates a healthy daily rhythm. Elevated evening (>50% of the morning value or > 1.8 µg/dL at night): indicates loss of normal physiological suppression, which is an important sign of Cushing’s syndrome.

Evening Serum Cortisol Test