Corticotropin: Definition, Function, Low Levels, Associated Diseases, Medical Test, Results and Risks

It is an adrenal hormone that acts on the adrenal (cortical) cortex in a regulatory (tropical) way.

The hormone itself is produced in the pituitary gland, that is, in the anterior portion of it.

The corticotropin is composed of 39 amino acids, forming a long polypeptide chain, and the first 13 of them are related to the stimulating hormones of the alpha melanocytes .

The relationship between where it is produced (pituitary gland) and where it acts (adrenal cortex) creates an axis, known as the hypothalamic-pituitary-adrenal axis.

Alternative Names of Corticotropin

  • ACTH (for its acronym in English).
  • Adrenocorticotropic hormone.
  • Serum adrenocorticotropic hormone.
  • ACTH highly sensitive.
  • Cosintropin, which is a form of ACTH medication.

ACTH function

ACTH acts on the adrenal cortex and causes the release of corticosteroids such as cortisol.

These corticosteroids are mainly what one would call stress hormones.

ACTH plays a role in helping regulate the amount of cortisol in the bloodstream relative to the amount that is produced.

The levels of this hormone usually decrease with increasing amounts of cortisol, so that there is a way to “plug” the amount.

Conversely, when cortisol levels are too low, ACTH will increase to stimulate the adrenal glands to secrete more cortisone to balance the amount of both in the body.

This is known as negative feedback, which is a common mechanism in the body to regulate hormone levels and the activities of hormone-producing organs.

Along with blood tests, a urinary free cortisol test or a urinary ketosteroid test can also sometimes be done in which the urine is collected over a 24-hour period.

Depending on the disease, ACTH can increase or decrease and both can be found by testing. Let’s discuss what happens in any case.

Causes of low levels of corticotropin

Lower hormone levels than normal may be due to:

  • Cushing’s syndrome related to an adrenal tumor.
  • Cushing’s syndrome due to steroid medication.
  • Conditions that affect the pituitary gland ( hypopituitarism ).
  • Side effect of pituitary surgery or radiotherapy.

Too little adrenocorticotropic hormone could lead to an adrenal gland that malfunctions due to insufficient production of cortisol.

Diseases due to ACTH malfunction

Excess:

The excess of ACTH causes a syndrome called Cushing’s disease where the body begins to store excess fat, increases the concentration of blood sugar and blood pressure.

This particular disease can be caused by both problems at the level of the adrenal system, but it can be caused mainly by ACTH overproduced by a pituitary tumor.

Deficiency:

Patients with chronic ACTH deficiency generally present with progressive symptoms of fatigue, anorexia, postural hypotension and weight loss.

The examination may reveal the pallor of the skin, in contrast to the hyperpigmentation of Addison’s disease and the loss of secondary sexual hair in female patients.

In severe ACTH deficiency, especially in childhood, hypoglycemia can occur when cortisol deficiency increases insulin sensitivity and decreases endogenous glucose production.

Hyponatremia is less common than in primary adrenal insufficiency due to the preservation of aldosterone secretion, but it may be the characteristic, particularly in older adults.

The test of corticotropin

It is a test that can help determine if the adrenal and pituitary glands are normal.

It is most often used when the doctor suspects disorders of the adrenal glands, such as Addison’s disease or pituitary insufficiency.

Normal values:

The plasma concentrations of corticotropin (ACTH) usually range between 10 and 60 pg / ml (2.2 and 13.3 pmol / l) at 8 a. M.

Values ​​decrease during waking hours and are generally less than 20 pg / mL (4.5 pmol / L) at 4 PM and less than 10 pg / mL (2.2 pmol / L), generally less than 5 pg / mL (1.1 pmol / L), within one hour after the usual time of falling sleep.

This circadian rhythm in plasma ACTH concentrations is the cause of the parallel changes in cortisol secretion by the adrenal glands and the resulting rhythm in serum cortisol levels.

This means that the time of day in which the sample is taken is an important determinant of the usefulness of plasma corticotropin measurement, which is often best interpreted with a simultaneous measurement of serum cortisol.

What do the abnormal results mean?

This test is useful to determine if you have:

  • Acute adrenal crisis.
  • Addison’s disease
  • Low pituitary function.
  • Pituitary tumors

How is the corticotropin test performed?

The doctor will measure Cortisol in your blood before and 60 minutes after an ACTH injection.

A blood sample obtained by venipuncture extraction is needed.

Once the blood has been collected, the doctor will use a needle to inject Cosyntropin.

Risks when performing the test

Veins and arteries vary in size from one patient to another. It is not a complex test, however, getting a blood sample from some people may be more difficult than others.

Some risks associated with blood collection are mild, but may include:

  • Excessive bleeding
  • Fainting or feeling dizzy.
  • Hematoma (accumulation of blood under the skin).
  • Infection (a slight risk every time the skin breaks).

What could affect the results of the test?

The results of your test may be affected if you:

  • You are under a lot of stress.
  • Recently he experienced a trauma.
  • Are you menstruating or are you pregnant?
  • You are taking certain medications, including steroids, hormones, or insulin.
  • He did not sleep well the night before the test.

Possible consequences during and after the test

When the needle is inserted to draw blood, some people may feel moderate pain, while others feel only a prick or stinging sensation. Afterwards, there may be something throbbing.

Recommendations before performing the test

The recommendation for pre-test preparation varies from person to person. In some cases it is recommended:

Increase carbohydrate intake, good rest the night before, avoid the consumption of food 6 hours before, inform the treating doctor about medicines you are taking.

In other cases there are no special recommendations.