Cortisol is a hormone produced in the adrenal glands that plays an important role in stress response, regulating blood sugar and metabolism, blood pressure, and immune function. It follows a diurnal rhythm, being highest in the morning and decreasing throughout the day. The hypothalamic-pituitary-adrenal axis regulates cortisol levels through a negative feedback loop. Too much cortisol over time can lead to Cushing's syndrome with symptoms like weight gain, high blood pressure, and mood changes. Too little cortisol may indicate Addison's disease and cause fatigue, low blood pressure, and weight loss requiring treatment.

1. Cortisol Blood Test
Submitted
by
A.Ajith B.sc Microbiology (DMLT)

2. Cortisol
 Cortisol is a hormone that affects almost every organ
and tissue in your body. It plays an important role in
helping you to:
 Respond to stress
 Fight infection
 Regulate blood sugar
 Maintain blood pressure
 Regulate metabolism, the process of how your body
uses food and energy

3. Adrenal Gland Cross Sections

4.  Cortisol is a steroid hormone, one of
the glucocorticoids, made in the cortex of the adrenal
glands and then released into the blood, which
transports it all round the body. Almost every cell
contains receptors for cortisol and so cortisol can have
lots of different actions depending on which sort of cells
it is acting upon. These effects include controlling the
body’s blood sugar levels and thus regulating
metabolism, acting as an anti-inflammatory, influencing
memory formation, controlling salt and water balance,
influencing blood pressure and helping development of
the foetus. In many species cortisol is also responsible
for triggering the processes involved in giving birth.

5.  Blood levels of cortisol vary throughout the day, but
generally are higher in the morning when we wake up,
and then fall throughout the day. This is called a diurnal
rhythm. In people that work at night, this pattern is
reversed, so the timing of cortisol release is clearly
linked to daily activity patterns. In addition, in response
to stress, extra cortisol is released to help the body to
respond appropriately.
 The secretion of cortisol is mainly controlled by three
inter-communicating regions of the body;
the hypothalamus in the brain, the pituitary gland and
the adrenal gland. This is called the hypothalamic–
pituitary–adrenal axis.

7.  When cortisol levels in the blood are low, a group of
cells in a region of the brain called the hypothalamus
releases corticotrophin-releasing hormone, which causes
the pituitary gland to secrete another
hormone, adrenocorticotropic hormone, into the
bloodstream. High levels of adrenocorticotropic
hormone are detected in the adrenal glands and
stimulate the secretion of cortisol, causing blood levels
of cortisol to rise. As the cortisol levels rise, they start to
block the release of corticotrophin-releasing hormone
from the hypothalamus and adrenocorticotropic
hormone from the pituitary. As a result, the
adrenocorticotropic hormone levels start to drop, which
then leads to a drop in cortisol levels. This is called
a negative feedback loop.

8.  What happens if I have too much cortisol
 Too much cortisol over a prolonged period of time can lead to a condition
called Cushing's syndrome. This can be caused by a wide range of factors, such as a
tumour that produces adrenocorticotropic hormone (and therefore increases cortisol
secretion), or taking certain types of drugs. The symptoms include:
 rapid weight gain mainly in the face, chest and abdomen contrasted with slender arms
and legs
 a flushed and round face
 high blood pressure
 osteoporosis
 skin changes (bruises and purple stretch marks)
 muscle weakness
 mood swings, which show as anxiety, depression or irritability
 increased thirst and frequency of urination.
 High cortisol levels over a prolonged time can also cause lack of sex drive and, in
women, periods can become irregular, less frequent or stop altogether (amenorrhoea).
 In addition, there has been a long-standing association between raised or impaired
regulation of cortisol levels and a number of psychiatric conditions such as anxiety and
depression. However, the significance of this is not yet clearly understood.

9.  What happens if I have too little cortisol?
 Too little cortisol may be due to a problem in the
pituitary gland or the adrenal gland (Addison's disease).
The onset of symptoms is often very gradual. Symptoms
may include fatigue, dizziness (especially upon
standing), weight loss, muscle weakness, mood changes
and the darkening of regions of the skin. Without
treatment, this is a potentially life-threatening condition.
 Urgent assessment by a specialist hormone doctor called
an endocrinologist is required when a diagnosis of
Cushing's syndrome or Addison's disease is suspected.