Know Your Blood Parameters: Cortisol
- Summarised by TGHC Editorial Team
- Aug 9, 2025
- 3 min read
Updated: Dec 10, 2025
Parameter Name
Cortisol
Cortisol is a steroid hormone produced by the adrenal glands, which are located on top of each kidney. It plays a crucial role in various bodily functions, including the regulation of metabolism, immune response, and the body's stress response. Understanding cortisol levels is essential for assessing overall health and well-being.
Test Type
Blood / Saliva / Urine
Cortisol can be measured through several types of tests, including blood tests, saliva tests, and urine tests. Blood tests are typically performed in the morning when cortisol levels are at their highest. Saliva tests can be done at home, usually at specific times during the day, to assess the diurnal variation of cortisol. Urine tests, particularly a 24-hour urine collection, provide an average cortisol level over an entire day, which can be particularly useful for diagnosing certain conditions.
Normal Range
Morning blood cortisol: 6 – 23 mcg/dL
Evening blood cortisol: 3 – 13 mcg/dL
The normal range for cortisol levels varies depending on the time of day due to its natural circadian rhythm. Typically, cortisol levels are highest in the early morning, helping to prepare the body for the day ahead, and gradually decrease throughout the day, reaching their lowest levels in the evening. Understanding these normal ranges is vital for interpreting test results accurately.
High Levels Indicate
Cushing's syndrome, stress, steroid use, adrenal tumors.
Elevated cortisol levels can indicate a variety of health issues. Cushing's syndrome, for instance, is characterized by excessive cortisol production, which can result from various causes, including pituitary adenomas or adrenal tumors. Chronic stress, whether physical or emotional, can also lead to prolonged high cortisol levels. Additionally, the use of corticosteroid medications can artificially raise cortisol levels in the body, necessitating careful evaluation of medication history when interpreting test results.
Low Levels Indicate
Addison's disease, adrenal insufficiency, pituitary dysfunction.
Low cortisol levels can signify adrenal insufficiency, a condition where the adrenal glands do not produce enough hormones. Addison's disease is a specific type of adrenal insufficiency often caused by autoimmune destruction of the adrenal glands. Pituitary dysfunction can also lead to inadequate stimulation of the adrenal glands, resulting in low cortisol production. Identifying low cortisol levels is crucial for diagnosing these conditions and initiating appropriate treatment.
Why It's Tested
To assess adrenal gland function, diagnose Cushing’s or Addison’s disease, and evaluate stress response.
Cortisol testing is essential for understanding adrenal gland function and diagnosing various disorders. It helps healthcare providers determine whether the adrenal glands are producing appropriate levels of cortisol in response to stress and metabolic needs. Testing is particularly important in cases where patients exhibit symptoms suggestive of adrenal disorders, such as unexplained weight changes, fatigue, or mood disturbances, guiding further diagnostic and treatment pathways.
Associated Symptoms (if abnormal)
High: Weight gain, hypertension, mood changes, muscle weakness.
Low: Fatigue, hypotension, weight loss, hyperpigmentation.
Abnormal cortisol levels can lead to a range of symptoms. High cortisol levels may cause significant weight gain, particularly around the abdomen and face, along with hypertension and changes in mood, such as anxiety or depression. Muscle weakness is also a common symptom associated with excess cortisol. Conversely, low cortisol levels can result in debilitating fatigue, low blood pressure (hypotension), unintentional weight loss, and hyperpigmentation, where the skin darkens in certain areas. Recognizing these symptoms is vital for timely intervention and treatment.
What To Do If Abnormal
Confirm with dexamethasone suppression or ACTH stimulation tests; endocrinology referral.
If cortisol levels are found to be abnormal, further testing is often required to confirm the diagnosis. Dexamethasone suppression tests can help determine if high cortisol levels are due to Cushing's syndrome, while ACTH stimulation tests can assess adrenal function in cases of low cortisol. Referral to an endocrinologist may be necessary for specialized evaluation and management of adrenal disorders, ensuring that patients receive comprehensive care tailored to their specific conditions.
Common Conditions Related
Cushing's syndrome, Addison's disease, adrenal insufficiency.
Several common medical conditions are associated with abnormal cortisol levels. Cushing's syndrome and Addison's disease are two primary disorders that directly involve cortisol regulation. Adrenal insufficiency, which may be primary (originating in the adrenal glands) or secondary (resulting from pituitary dysfunction), also plays a significant role in cortisol-related health issues. Understanding these conditions and their relationship with cortisol levels is essential for effective diagnosis and treatment.
Nutrition or Lifestyle Connection
Manage stress, avoid excess caffeine, maintain balanced diet.
Nutrition and lifestyle choices can significantly influence cortisol levels and overall health. Managing stress through techniques such as mindfulness, meditation, or regular physical activity can help maintain balanced cortisol levels. Additionally, avoiding excessive caffeine and sugar intake can prevent spikes in cortisol associated with stress. Maintaining a balanced diet rich in whole foods, healthy fats, and adequate hydration supports adrenal health and hormonal balance, contributing to improved well-being and resilience against stressors.
References (APA Format)
Melmed, S. et al. (2016). Williams Textbook of Endocrinology (13th ed.). Elsevier.
MedlinePlus. (2023). Cortisol Test. https://medlineplus.gov/lab-tests/cortisol-test/
