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What is a dexamethasone test? Dexamethasone test Small dexamethasone test.

Dexamethasone Suppression Test (DST) Dexamethasone is a long-acting synthetic glucocorticoid with a long half-life. Approximately 1 mg of dexamethasone is equivalent to 25 mg of cortisol. The dexamethasone suppression test is used to confirm the diagnosis of depression with melancholia or endogenous depression. Procedure. The patient is administered 1 mg of dexamethasone orally at 23:00; Plasma cortisol measurements are taken at 8 a.m., as well as at 4 and 11 p.m. If the plasma cortisol level exceeds 5 mg/dL, this indicates a lack of suppression and is considered a pathological or positive reaction. Suppression of cortisol indicates that the hypothalamic-adrenal-pituitary axis is functioning normally. As early as 1930, it was shown that dysfunction of these systems is caused by stress.

TPD can be used to monitor the effectiveness of treatment. Normalization of this test, however, does not mean that antidepressant treatment can be stopped, since. TPD sometimes normalizes before clinical signs of depression disappear.

There is evidence that patients who respond positively to TPD, especially those with cortisol levels greater than 10 mg/dL, typically respond well to somatic therapies such as electroconvulsive therapy (ECT) or cyclic antidepressant therapy. However, due to the varying sensitivity and specificity of TPD, false results, both positive and negative, sometimes occur.

False-positive results of this test may occur if the patient has received phenitol, barbiturates, meprobamates, glutethimide, methyprylon, methaqualone, carbamazepine, as well as in the presence of heart failure, hypertension, renal failure, cancer in the dissemination stage , serious infectious diseases, recent severe injuries, surgical interventions, for fever, nausea, dehydration, diseases of the temporal lobe, treatment with large doses of estrogen hormones, pregnancy, Cushing's disease, diabetes, severe weight loss (eating disorders, anorexia), alcohol abuse.

False negative results can be caused by hypofunction of the pituitary gland, Addison's disease, long-term therapy with synthetic steroids, indomethacin, large doses of cyproheptidine and large doses of benzodiazepines.

Large and small dexamethasone tests are an important diagnostic tool used by endocrinologists. These functional tests allow us to determine the presence of excess cortisol production, as well as the suspected cause of this phenomenon. They are necessary for the reason that analysis to determine the basal level of cortisol is a low-informative study. To conduct tests and obtain reliable results, a number of specific requirements must be met.

Small dexamethasone test

This test is called small because of the low dose of the drug used during it. A modification of this method is currently being used, which is called the overnight suppression test with Dexamethasone. This test indicates the presence of increased cortisol production and is used when identifying symptoms in a patient that are suspicious for hypercortisolism:

  • specific (Cushingoid) type of obesity - thin arms and legs, redistribution of fat with deposition in the upper half of the body;
  • purple stretch marks;
  • moon-shaped face;
  • arterial hypertension;
  • menstrual irregularities and infertility in women.

Hypercortisolism occurs as a result of the autonomous production of cortisol by the adrenal cortex (corticosteroma, cortical hyperplasia) or when the synthesis of the substance is stimulated by high levels of adrenocorticotropic hormone (ACTH) in pituitary adenoma (Cushing's disease) or ectopic ACTH syndrome (abnormal synthesis of ACTH outside the pituitary gland, occurring most often with small cell lung cancer).

Disorders in the field of gynecology occur only with Cushing's disease. With this pathology, in addition to an increase in cortisol levels, hyperandrogenism develops - an increase in the amount of male hormones in a woman’s blood.

Methodology

The test is performed in an outpatient or inpatient setting. No specific preparation is required for it. For women, this test can be performed on any day of the menstrual cycle. Before the test, in order to avoid unreliable results, it is advisable to discontinue the following medications:

  • barbiturates for 1 day;
  • anticonvulsants for 1 day;
  • Rifampicin for 1 day;
  • combined oral contraceptives 6 weeks before the test.

The patient needs to take two Dexamethasone tablets, which contain 1 mg of the active substance, at 23:00. At 8:00 the next day, blood is drawn to determine cortisol levels.

Interpretation of results

Normally, this dose of Dexamethasone suppresses the secretion of adrenocorticotropic hormone from the pituitary gland. As a result, its stimulating effect on cortisol synthesis is reduced. For this reason, in healthy people, after an overnight suppression test, the cortisol level at 8 am the next day does not exceed 50 nmol/l. Such a test is called positive.

If the readings are above 50 nmol/l, the test is negative, which indicates the presence of hypercortisolism, but does not allow one to determine its nature. To determine the probable cause, a large dexamethasone test is performed.

The test results should be interpreted by an endocrinologist.

Large dexamethasone test

The indication for this study is a negative overnight suppression test. A small dose of Dexamethasone (1 mg) in a healthy person leads to suppression of ACTH synthesis. If you have a pituitary adenoma that produces an excess amount of the substance, this does not happen.

... timely diagnosis and adequate treatment can improve the quality of life of patients and reduce the risk of death.

Endogenous hypercortisolism or Cushing's syndrome is a complex of clinical symptoms that are caused by prolonged exposure to corticosteroids on the body due to their excess endogenous production. Endogenous hypercortisolism can be ACTH-dependent (most often) and ACTH-independent (ACTH adrenocorticotropic hormone). The most common cause of ACTH-dependent hypercortisolism is corticotropinoma of the pituitary gland (Cushing's disease or hypercortisolism of central origin), less often - ectopic production of ACTH by a tumor or, extremely rarely, ectopic production of corticotropin-releasing hormone. In most cases, the cause of ACTH-independent hypercortisolism is a tumor of the adrenal cortex (corticosteroma or, less commonly, adrenocortical carcinoma). Let's consider the basic principles and tests of laboratory diagnostics of endogenous hypercortisolism.

Remember! In practice, the most common cause of the development of clinical signs of hypercortisolism is exogenous intake of glucocorticoids, and therefore Before conducting diagnostic studies, it is extremely important to exclude the causes of the development of endogenous hypercorticism:
firstly, possible options for corticosteroid drugs entering the body;
secondly, pseudo-Cushingoid conditions (otherwise known as functional hypercortisolism), which are accompanied by hypercortisolemia without the development of clear clinical signs of hypercortisolism (depression and other mental disorders, alcoholism, obesity, hypothalamic syndrome, uncompensated diabetes mellitus, liver disease, pregnancy).

According to the recommendations of the European Society of Endocrinology (2008) examination for the presence of endogenous hypercortisolism is prescribed in the following cases:
the presence of pathological conditions that do not correspond to age: osteoporosis, arterial hypertension in young people;
the presence of several progressive pathological symptoms that are pathognomonic for hypercortisolism (for example, dysplastic obesity, trophic changes in the skin, proximal myopathy - muscle weakness and muscle atrophy, menstrual irregularities and decreased libido as a consequence of secondary hypogonadism, hirsutism, etc.)
the appearance of purple stretch marks more than 1 cm wide;
combination of growth disturbance and weight gain in children;
the presence of an incidentaloma (an adrenal neoplasm that was accidentally discovered by research methods performed for other diagnostic purposes).

To determine increased production of cortisol in the body (a manifestation of hypercortisolism), the following laboratory [diagnostic] tests are used:

(1 ) Overnight suppression test with 1 mg dexamethasone(or PTD1). The test is based on the suppression of ACTH secretion and, as a consequence, a decrease in cortisol production in response to dexamethasone. No preliminary preparation is required. It is possible to perform the test on an outpatient basis if you are confident that the patient will take the pills on time. Methodology: the patient takes 1 mg of dexamethasone at 23.00, at 8 - 9 o'clock the next morning, blood is taken to study cortisol levels. Normally, cortisol levels are suppressed below the lower limit of normal for a given laboratory, usually less than 5 mcg/dL (<3 мкг/дл по рекомендациям других авторов) или 140 (100) нмоль/л. Однако ряд исследователей предлагают использовать более жесткие критерии: снижение кортизола должно быть менее 1,8 мкг/дл (50 нмоль/л).

(2 ) 48-hour suppression test with 2 mg per day dexamethasone(or PTD2). Some authors prefer to use this test as a screening test, especially when a pseudocushingoid condition is suspected, as well as to exclude subclinical Cushing's syndrome. Methodology: dexamethasone is prescribed 0.5 mg every 6 hours for 48 hours, cortisol is determined at 9 a.m. on the 3rd day (6 hours after taking the last dexamethasone tablet). Normal cortisol levels are less than 1.8 mcg/dL (50 nmol/L).

(3 ) Study of the level of free cortisol in saliva in the evening(double definition). Normal salivary cortisol levels at 23–24 hours do not exceed 145 ng/dL (4 nmol/L) using enzyme-linked immunosorbent assay (ELISA) or mass spectrometry.

(4 ) Determination of free cortisol content in daily urine(double definition). Patients should be explained the rules for collecting daily urine: the first portion of urine after sleep is not collected, but all subsequent ones are collected, including the morning portion of the second day. The container for collecting urine should be kept in the refrigerator, but not frozen. The test has high sensitivity (95%), but low specificity (it is believed that if > 250 mcg of cortisol is excreted per day, then the presence of endogenous hypercortisolism is beyond doubt).

(5 ) Blood cortisol level test at 11 p.m.(used as an additional test if the patient is taking anticonvulsants, as well as in case of questionable results with PTD1, and when studying the 24-hour urine cortisol content). Measurement of serum cortisol at night (23.00) can be carried out during sleep (blood should be taken no later than 5 - 10 minutes after waking up; preliminary catheterization facilitates this procedure) or while awake. A serum cortisol level of more than 207 nmol/L (7.5 μg/dL) during wakefulness or more than 50 nmol/L (1.8 μg/dL) in a sample taken during sleep is characteristic of endogenous hypercortisolism (Cushing's syndrome ).

(6 ) Combined test: PTD2 + stimulation of corticotropin-releasing hormone(can be used if the results of determining free cortisol in daily urine are questionable, as well as the results obtained during PTD1 and PTD2. Procedure: dexamethasone is taken 0.5 mg every 6 hours for 48 hours (start of administration at 12.00 noon), corticotropin-releasing hormone at a dose of 1 mcg/kg (maximum 100 mcg) is administered intravenously at 8.00 (2 hours after taking the last dose of dexamethasone). The level of cortisol in the blood is determined after 15 minutes. Its increase is more than 1.4 mg/dl ( 38 nmol/l) confirms the diagnosis of endogenous hypercortisolism (it should be noted that corticotropin-releasing hormone preparations are currently not registered in the Russian Federation).

The dexamethasone suppression test is primarily used to diagnose Cushing's syndrome. Cushing's syndrome indicates that you have abnormally high levels of cortisol. Cortisol is a steroid hormone produced by the body during times of high levels of stress. (Abnormally low cortisol levels may be a sign of Addison's disease, which is not diagnosed by this test.)

UsesWhat test addresses

The Dexamethasone Suppression Test measures how your cortisol levels are affected by taking dexamethasone. Dexamethasone is a man-made corticosteroid similar to what humans produce naturally from their adrenal glands. discontinue to replace a natural chemical if your body does not produce enough of it. It can also be prescribed as an anti-inflammatory agent, which is used to treat arthritis and various blood, kidney and eye diseases.

Your adrenal glands are located on top of your kidneys. In addition to producing cortisol, they produce steroid hormones such as:

  • androgens, which are male sex hormones
  • cortisol
  • epinephrine
  • norepinephrine

The test is also used to determine how well the adrenal glands respond to adrenocorticotropic hormone (ACTH). ACTH is a hormone produced by the pituitary gland in the brain. It has a number of functions, including the production of corticosteroids. Too much ACTH can cause Cushing's syndrome. In a healthy person, when the pituitary gland makes less ACTH, the adrenal glands make less cortisol. Dexamethasone should decrease the amount of ACTH, which should then decrease the amount of cortisol.

If you are currently taking the corticosteroid dexamethasone, your doctor may recommend a dexamethasone suppression test to determine how it affects your blood cortisol levels.

Dexamethasone relieves inflammation associated with arthritis and severe allergies, among other conditions. When you take dexamethasone, which is very similar to cortisol, it should reduce the amount of ACTH released into your blood. If your cortisol levels are high after taking dexamethasone, it is a sign of an abnormal condition.

Preparation Preparing for the test

Before the test, your doctor will tell you to stop taking certain prescription medications that may affect the results. These include:

  • birth control pills
  • barbiturates
  • phenytoin, which is used to treat seizures
  • corticosteroids
  • estrogen
  • spironolactone, which is used to treat congestive cirrhosis, ascites, or kidney disease
  • tetracycline, which is an antibiotic

Procedure. How does the test work?

The two options for the dexamethasone suppression test are the low-dose test and the high-dose test. Both forms of the test can be performed overnight or over a three-day period. The standard test for both is a test that spans three days. During both forms of the test, your doctor will give you a certain amount of dexamethasone and later measure your cortisol levels. A blood sample is also required.

Blood sample

The blood will be drawn from a vein inside your lower arm or the back of your arm. First, your doctor will wipe the site with an antiseptic. They may wrap an elastic band around the top of your arm to encourage the veins to swell with blood, making them more visible. Your doctor then inserts a thin needle into a vein and collects a blood sample into a tube attached to the needle. The strip is removed and gauze is applied to the site to prevent further bleeding.

Low Dose Night Dose Test

  • Your doctor will give you 1 milligram of dexamethasone at 11 p.m. m.
  • They will draw a blood sample at 8 a. m. the next morning to check your cortisol levels.

Standard low dose test

  • You collect urine samples over three days and store them in 24-hour collection bottles.
  • On the second day, your doctor will give you 0.5 milligrams of oral dexamethasone every six hours for 48 hours.

High Dose Night Dose Test

  • Your doctor will measure your cortisol levels in a morning test.
  • You will be given 8 milligrams of dexamethasone at 11 p.m. m.
  • Your doctor will take a blood sample at 8 a.m. m. to measure cortisol levels.

Standard high dose test

  • You will collect urine samples for three days and store them in 24-hour containers.
  • On the second day, your doctor will give you 2 milligrams of oral dexamethasone every 6 hours for 48 hours.

ResultsGetting results

An abnormal low dose test result may indicate that you are experiencing excessive cortisol release. This is called Cushing's syndrome. This disorder may be caused by an adrenal tumor, a pituitary tumor, or a tumor elsewhere in your body that produces ACTH. The results of the high-dose test may help isolate the cause of Cushing's syndrome.

High cortisol levels can also be caused by a number of other conditions, such as:

  • heart attack
  • heart failure
  • poor diet
  • sepsis
  • overactive thyroid > anorexia nervosa
  • depression
  • untreated diabetes
  • alcoholism
  • Risks What are the risks of the test?

As with all blood circulation, there is a minimal risk of minor bruising at the needle site. In rare cases, the moisture may become swollen after drawing blood. This condition, known as phlebitis, can be treated with a warm compress several times a day. Constant bleeding may be a problem if you have a bleeding disorder or are taking blood thinners such as warfarin (Coumadin) or aspirin.

After the test. After the test

Even with an abnormally high result, your doctor may recommend further tests to diagnose Cushing's syndrome. If this disorder is diagnosed, you will be given appropriate medications to control high cortisol levels.

If cancer is causing high cortisol levels, your doctor will recommend further tests to determine the type of cancer and appropriate treatment.

If your high cortisol levels are caused by other disorders, your doctor may recommend a different course of treatment.

Dexamethasone is a powerful corticosteroid used to suppress inflammatory reactions. This substance affects a specific system of the human body. It controls reactions to situations, and in medical terminology is referred to as the HPA (hypothalamic-pituitary-adrenal). To study its functioning, a dexamethasone test is prescribed.

When is it necessary to test with dexamethasone?

The dexamethasone test is used very often in medical practice. This research method is used to diagnose pathological processes in various body systems.

  • This analysis allows us to identify the slightest disturbances in the production of the stress hormone or cortisol at the initial stage, and establish the causes of adrenal dysfunction.
  • The results of the study are necessary for differentiating endocrinological diseases and identifying neoplasms of various etiologies.
  • The test is often prescribed for affective disorders. It allows you to establish the integrity of the HPA axis.
  • In gynecology, such an examination is carried out when clear signs of hyperandrogenism and infertility appear.
  • Practicing psychiatrists use a test with dexamethasone to identify endogenous.

A dexamethasone test is prescribed for pathological conditions caused by impaired cortisol levels. They appear as:

  • Dysplastic
  • Myasthenia gravis
  • Osteoporosis
  • Hypertension
  • Hirsutism in women
  • Menstrual irregularities
  • Chronic thrush
  • Amenorrhea
  • Urolithiasis
  • Chronic pyelonephritis
  • Decreased libido in men and women
  • Erectile dysfunction
  • Purple stretch marks on the abdomen more than 1 cm wide
  • Trophic ulcers and pustular skin lesions
  • Decreased immune defense
  • Insulin sensitivity disorders
  • Chronic fatigue
  • Fatigue
  • Depressed
  • Sleep disorders
  • Systematic appearance of a euphoric state

Also, reasons for testing with dexamethasone may be slow healing of wounds and minor scratches, the unreasonable appearance of bruises on the body and sudden changes in weight.

Signs of cortisol imbalance in the body appear individually or in combination.

A dexamethasone test is prescribed by a gynecologist, endocrinologist or urologist. Typically, the test is recommended as part of a comprehensive examination after a physical examination.

Venous blood is used for the study. The collection of biomaterial is carried out in special medical laboratories or in a hospital setting.

To reduce the percentage of error in the result, it is necessary to adhere to the manipulation technique:

  • Blood is drawn from a vein in the morning or at the time prescribed by the doctor.
  • The biomaterial is placed in a sterile tube
  • For blood preservation, it is permissible to use sterile tubes with gel

It is important that all sterility rules are observed in the laboratory. Medical staff should use disposable consumables and sterile gloves.

To ensure that the test results are as accurate as possible, doctors recommend preliminary preparation. To do this you need:

  • Donate blood on an empty stomach
  • 8-10 hours before consuming heavy fatty foods
  • Limit emotional stress in 12 hours
  • Stop hormone therapy 2 days before the test
  • For 1-2, limit physical activity and not go to the gym
  • Do not smoke 2-3 hours before the collection
  • Stop drinking alcohol and painkillers one day before

Blood donation is carried out in a calm state. To do this, before the manipulation you should sit or lie down for 15-20 minutes.

The following factors can distort the analysis results:

  • Long-term use of potent medications
  • Abuse
  • Taking hormonal medications
  • Obesity
  • Diabetes mellitus of any type
  • Diencephalic syndrome
  • Chronic hepatitis
  • Pregnancy

If one or more factors are present, the condition is corrected before the test and a dexamethasone test may be prescribed several times.

Dexamethasone test: protocol and explanation

To diagnose pathology, two main types of dexamethasone test are used:

  • Small
  • Big

Each type of test is performed in several ways. In diagnostics there is frequent use of:

  • Classic
  • Short

Protocol for the small classic test with dexamethasone:

  • On the first day, in the morning at 8.00 am, blood is drawn to determine the initial cortisol level.
  • For two days, every 6 hours, dexamethasone in 0.5 m tablets is taken orally. A single dose is 1 pc.
  • On the third day at 8 o'clock in the morning, blood is donated to determine the concentration.
  • The accuracy of the method is within 98-99%.
  • In the short version, a blood test is taken at 8.00 to determine the baseline cortisol level. On the same day at 11:00 pm, two 0.5 mg dexamethasone tablets are taken orally. The next morning, blood is donated again for cortisol concentration.
  • The accuracy of this method is 95-96%.
  • The decoding of the indicators is the same for the two options. If the level of cortisol after dexamethasone decreases by half, this is considered normal or is a sign of functional hypercortisolism. With such indicators, the sample is defined as positive.
  • The test is considered negative if there are no changes in cortisone levels or if they increase. This result is a sign of endogenous hypercortisolism.
  • A large test with dexamethasone is performed if the small test is negative. Using this analysis, the disease is differentiated from Itsenko Cushing's syndrome.

In the classical method, when carrying out this test, a certain sequence is followed:

  • On the first day at 8 a.m., blood is drawn to determine the initial cortisol level.
  • For two days, every 6 hours, take 4 tablets of dexamethasone at a dosage of 0.5 mg. Single dosage 2 mg.
  • On the third day, in the morning at 8 o’clock, the cortisol level is analyzed again.
  • The test accuracy is at least 98%.
  • In the short method, on the first day in the morning at 8 o’clock, a blood test is taken for basic cortisol. At 23.00, 8 mg of dexamethasone is taken in one dose. These are 16 tablets of 0.5 mg. At 8.00, blood is again donated for cortisol concentration.
  • The sensitivity of the test is within 96%.

Decryption for two methods:

A decrease in the concentration of free cortisol by half or more is considered a sign of Itsenko's Cushing's disease. In this case, the test is considered positive. If the indicators do not change, the sample is defined as negative.

While watching the video you will learn about food.

The dexamethasone test is an affordable test that can detect changes in cortisol levels at an early stage. This will allow doctors to quickly make an accurate diagnosis and select the most effective therapeutic method.