Cortisol hormone
Cortisol is a steroid glucocorticoid hormone that is produce and release in
bloodstream by adrenal glands, which are located on top of kidneys in response to
stress. Cortisol the primary hormone involved in the body’s fight-or-flight response to
stress.
It plays many important roles, including:
• Regulating body’s stress response.
• Helping control body’s metabolism.
• Suppressing inflammation.
• Regulating blood pressure.
• Regulating blood sugar.
• Helping control sleep-wake cycle.
Body cortisol levels control
Hypothalamus, a small area of brain involved in hormonal regulation, pituitary gland,
a tiny gland located below in brain, regulate the production of cortisol in adrenal
glands. When the levels of cortisol in blood fall, the hypothalamus releases
corticotrophin-releasing hormone (CRH), which directs the pituitary gland to produce
adrenocorticotropic hormone (ACTH). ACTH then stimulates adrenal glands to produce
and release cortisol.
Therefore, an optimal level of cortisol, the hypothalamus, pituitary gland and adrenal
glands must all be functioning properly.
Normal cortisol levels
The level of cortisol in blood, urine and saliva normally peaks in the early morning and
declines throughout the day, reaching its lowest level around midnight. This pattern
can change if a work at night shift and sleep at different times of the day.
the normal ranges for most tests that measure cortisol levels in blood, are:
• 6 a.m. to 8 a.m.: 10 to 20 micrograms per deciliter (mcg/dL).
• Around 4 p.m.: 3 to 10 mcg/dL.
• Normal ranges can vary from lab to lab, time to time and person to person.
Causes of hypercortisolism (Cushing’s syndrome)
Taking large amounts of corticosteroid medications, such as prednisone, prednisolone
or dexamethasone, for treatment of other conditions.
Tumors that produce adrenocorticotropic hormone (ACTH) in pituitary gland. More
rarely, neuroendocrine tumors in other parts of your body such as your lungs can
cause high cortisol levels.
Adrenal gland tumors or excessive growth of adrenal tissue (hyperplasia).
Signs & symptoms of high cortisol levels
Common signs and symptoms of higher-than-normal cortisol (depend on how
elevated cortisol levels) include are:
• Weight gain, especially in face and abdomen.
• Fatty deposits between shoulder blades.
• Wide, purple stretch marks on abdomen (belly).
• Muscle weakness in upper arms and thighs.
• High blood sugar, which often turns into Type 2 diabetes.
• High blood pressure (hypertension).
• Excessive hair growth (hirsutism) in people assigned female at birth.
• Weak bones (osteoporosis) and fractures.
Causes of low cortisol levels (hypocortisolism)
Primary adrenal insufficiency: most commonly caused by an autoimmune reaction
which is called Addison’s disease. Adrenal hemorrhage (infection or blood loss to the
tissues). All of these situations limit cortisol production.
Secondary adrenal insufficiency: an underactive pituitary gland (hypopituitarism) or a
pituitary tumor can limit ACTH production so limited cortisol secretion.
Stopping very quickly after a long period of use treatment with corticosteroid
medications.
Symptoms of lower-than-normal cortisol levels, or adrenal insufficiency, include
Fatigue, weight loss, Poor appetite, Low blood pressure (hypotension).
Cortisol test
Cortisol levels are measured with lab tests. These may be blood tests, which measure
levels of the hormone in the bloodstream, or saliva tests, which measure cortisol
levels in a saliva sample. Cortisol testing is typically done early in the morning, when
levels are normally highest.
Often, to produce the most accurate results, testing is repeated in the afternoon of
the same day. Cortisol testing is often done in conjunction with ACTH level tests, since
this pituitary gland hormone works to regulate cortisone levels. ACTH tests measure
levels of the hormone in the bloodstream.
However, it is important to note that if your tests show that your cortisol and/or ACTH
levels are abnormal – too high or too low – following up on those results with a visit to
your healthcare provider is essential. Abnormal levels of these important hormones
require further examination and testing.
Laboratory Test Reference Guide
Unit of measurement is nmol/L Minimum Volume 0.2 mL plasma or serum
Method Cobas Pro ECLIA (electrochemiluminescence immunoassay)
Reference interval 0600 – 1000 hrs : 170 - 500 nmol/L
Samples collected outside this period will be reported with the following comment:
“The cortisol reference interval is not well defined for the time of collection.”
Additional comments are added:
When cortisol is < 100 on a sample collected between 0600 – 1000:
“A cortisol result < 100 nmol/L is suspicious of adrenal insufficiency.
When cortisol is > 300 on a sample collected between 0600 – 1000:
“In the absence of acute illness, this cortisol result suggests adrenal insufficiency is
unlikely.”
Following Synacthen Stimulation (0.25 mg IM)
30 minutes:” A result ≥ 400 nmol/L suggests adequate adrenal reserve”
60 minutes:” A result ≥ 460 nmol/L suggests adequate adrenal reserve”
Following Dexamethasone Suppression (1mg oral given at 2300 hr) -
0800 hrs. the cut-off for “normal suppression” is 50 nmol/L or below
