Cortisol, Serum (Morning Sample)
Understanding Cortisol, Serum (Morning Sample)
What is Cortisol, Serum (Morning Sample)?
The Cortisol, Serum (Morning Sample) is a blood test that measures the level of cortisol, a steroid hormone produced by the adrenal gland. It is typically done in the morning when cortisol levels are at their peak, helping diagnose conditions associated with adrenal gland functioning, such as Cushing’s syndrome or Addison’s disease.
Cortisol is a vital hormone produced by the adrenal glands, two small glands that are located above the kidneys. A gland in your brain, called the pituitary gland, makes a hormone that tells your adrenal glands how much cortisol to make.
Cortisol affects almost every organ and tissue in your body. Its physiological functions include regulating carbohydrate metabolism and the distribution of electrolytes and water. Cortisol also has immunosuppressive and antiinflammatory activity hence it helps your body respond to stress (cortisol is sometimes called the "stress hormone"), reduce inflammation, regulate blood sugar and metabolism (how your body uses food for energy) and control blood pressure. If your cortisol levels are too high or too low, it may mean you have a disorder of your adrenal glands, a problem with your pituitary gland, or a tumor that makes cortisol.
Increased levels of cortisol are associated with Cushing syndrome, Adrenal and Pituitary adenoma/carcinoma, ectopic Adrenocorticotropic Hormone (ACTH) production, glucocorticoid therapy, stress, depression, hypoglycemia and hyperthyroidism. Decreased levels are seen in Addison's disease, generalized adrenal hypofunction or a defect in the metabolic pathway for cortisol biosynthesis. The Cortisol, Serum (Morning Sample) test can help diagnose diseases such as Cushing syndrome and Addison’s disease which can lead to either too much or too little production of cortisol. This test also helps evaluate how well the pituitary and adrenal glands are working.
Cortisol levels in the body are controlled by ACTH, a hormone made by the pituitary gland. ACTH is released in response to another hormone called corticotropin-releasing hormone (CRH), which is produced by the hypothalamus. This process creates a daily cycle, with cortisol levels peaking in the early morning (6 a.m-8 a.m) and dropping to their lowest point (nadirs) around 11 p.m.
The Cortisol, Serum (Morning Sample) test is usually conducted in the morning because cortisol levels are highest at this time, providing the most accurate assessment of adrenal gland function. This morning measurement helps establish a consistent baseline for evaluating cortisol health. Measuring cortisol levels later in the day can also help differentiate between normal cortisol levels and conditions like Cushing’s Syndrome, as cortisol levels naturally decrease towards evening. It is noteworthy that cortisol levels can be influenced by systemic diseases and stress.
Your doctor will likely have you do the test early in the morning because cortisol levels fluctuate throughout the day, influenced by the body’s circadian rhythm. You may be asked not to do any vigorous exercise the day before the test.
Lab test results may vary across laboratories. Abnormal test results require an expert interpretation, therefore, never try to self-medicate at home based solely on these results, and always consult a doctor for proper understanding of the test results.
What is Cortisol, Serum (Morning Sample) used for?
The Cortisol, Serum (Morning Sample) test is done:
- To help diagnose Cushing’s syndrome (excessive cortisol) and Addison’s disease (adrenal insufficiency)
- To assess cortisol levels as an indicator of body’s response to stress
- To assess the functioning of the pituitary gland as it regulates cortisol production
- To monitor cortisol levels in individuals receiving hormone replacement therapy
- To investigate the cause of symptoms such as unexplained weight changes, fatigue, fatigue, mood changes etc which may be associated with cortisol imbalance
- To help evaluate sleep disorders such as insomnia
- As a part of screening for conditions influenced by cortisol levels such as metabolic syndrome
What does Cortisol, Serum (Morning Sample) measure?
The Cortisol, Serum (Morning Sample) test measures the levels of cortisol hormone in the blood. Cortisol is a vital hormone produced by the adrenal glands in response to stress and plays an important role in various bodily functions such as metabolism, immune response and body’s stress response system.
The Cortisol, Serum (Morning Sample) test is conducted during the morning because cortisol levels fluctuate throughout the day, typically peaking in the early morning and gradually declining throughout the day and then into the evening. By measuring the cortisol levels in the morning, the doctors can assess the body’s natural rhythm (circadian rhythm) and evaluate how well the adrenal glands and pituitary glands are working. Deranged cortisol levels can indicate conditions such as adrenal insufficiency (Addison’s disease), cortisol excess (Cushing’s syndrome) or other disorders affecting these glands. Additionally, this test helps diagnose and monitor conditions related to stress, sleep disorders, metabolism and overall hormone balance.
Interpreting Cortisol, Serum (Morning Sample) results
Interpretations
Normal cortisol levels in the blood:
· 6 to 8 a.m.: 10 to 20 µg/dL
· Around 4 p.m.: 3 to 10 µg/dL
· Around 12 a.m.: Less than 5 µg/dL
Normal cortisol levels may vary among individuals. Increased or decreased cortisol levels can be assessed only if the cortisol level in blood does not follow the diurnal pattern as it should.
Cortisol levels may fall outside the normal range for the time of day due to diseases or due to lifestyle factors such as irregular sleeping times.
Reference range may vary from lab to lab*
Causes of increased cortisol levels:
· Long-term treatment with glucocorticosteroid hormones like prednisone, dexamethasone, etc.
· Pituitary tumors that increase ACTH production
· ACTH-producing tumors in other parts of the body
· Adrenal tumors that increase cortisol secretion
· Congenital Adrenal Hyperplasia, a disease which causes excessive growth of adrenal gland cells
· Recent surgery, illness, injury, or sepsis
· CRH-producing tumors in rare cases
Causes of decreased cortisol levels:
· Reduced cortisol production due to damage or diseases of the adrenal gland (primary adrenal insufficiency) like Addison’s disease
· Reduced ACTH production due to reduced activity of the pituitary gland or pituitary tumors (secondary adrenal insufficiency)