ACTH Test

ACTH also known as adrenocorticotropic hormone is a hormone produced by the pituitary gland. This hormone in turn regulates the production of another important hormone cortisol, made by adrenal glands. Cortisol, known as a 'stress hormone', controls varied reactions in our body that take place in response to stress. Cortisol regulates blood pressure and blood sugar levels in the body and helps in maintaining immune function and anti-inflammatory processes. ACTH travels through the bloodstream to the adrenal glands and stimulates the adrenals to release cortisol. An ACTH blood test is done to measure the level of the adrenocorticotropic hormone in the blood.

Too much or too little ACTH level reveals problems related to adrenal glands or pituitary glands. High level of ACTH points to problems with adrenal glands and low level of ACTH may imply defective pituitary glands. The results of ACTH test is extremely useful in diagnosing Cushing syndrome and adrenal insufficiency.

Higher values of ACTH test are associated with one of the following conditions:

• Addison's disease
  
  
• Adrenal Hyperplasia
  
  
• Cushing's disease
  
  
• Tumor in the adrenal glands or pituitary glands
  
  
• Ectopic ACTH, which means ACTH made by a tumor outside the pituitary gland

Lower levels of ACTH could mean adrenal tumor, Exogenous Cushing syndrome or hypopituitarism, a pituitary dysfunction leading to little or no production of hormone.

Preparing for the test

Patient should not eat or drink for 10 hours prior to the test. It is advisable to take a diet low in carbohydrates for two to three days before the test. Exercise and alcohol should be avoided for 12 hours before the test. Few steroid medications result in low levels of ACTH, hence patient should share all the information regarding the current medication with the doctor. Patient should not have undergone any medical test that uses a radioactive tracer for a week before an ACTH test.

ACTH levels do not remain in the same range through the day. The plasma ACTH levels are highest in the morning and start to decline during the waking hours. Therefore, blood is usually collected in the morning hours or multiple blood samples are sought for accurate diagnosis.

The Normal reference range is as follows:

Morning: Less than 80 pg/mL or less than 18 pmol/L

Evening: Less than 50 pg/mL or less than 11 pmol/L

A significant deviation from the normal range could mean defective adrenal glands or pituitary gland and further investigation is ordered for the accurate diagnosis.

Addison's disease

Addison's disease also known as chronic adrenal insufficiency is a hormonal disorder characterized by tissue necrosis and granulomatous appearance. Addison's disease occurs to people irrespective of age and gender. Addison's disease is also known as hypocortisolism as it is associated with insufficient production of cortisol from the adrenal glands.

Cortisol belongs to the class of glucocorticoid hormones. They are released from the cortex of the adrenal glands located on top of the kidneys. Cortisol has a significant function in the body and is associated with main organ system functions in maintaining the homeostasis in the body. Cortisol is essential in protein, carbohydrate and fat metabolism. It also helps in the regulation and release of insulin for blood sugar balance.

The other important functions of cortisol include maintenance of blood pressure, cardiovascular activity and inflammatory response process associated with the immune system. The level of cortisol in the body is used as a determination of stress management. Cortisol has precursors for its release such as the adrenocorticotropic hormone released due to the stimulus associated with the hypothalamus and pituitary gland.

Clinical manifestations

Addison's disease etiology is predominantly based upon the function of the adrenal gland and the release of cortisol regulated by the pituitary gland. Insufficient cortisol production may be due to impairment of adrenal glands which is categorized as the primary phase in Addison's disease occurrence. The secondary factors are associated with release of adrenocorticotropic hormone levels from the pituitary gland to stimulate the adrenal gland. The tertiary factors are associated with insufficient release of corticotrophin releasing hormone from the hypothalamus.

Significant clinical manifestations include anorexia, vomiting, hypoglycemia, weight loss, cutaneous and mucosal pigmentation, hypernatremia, hyperkalemia, hypotension caused due to extra cellular fluid loss. Excess melanin production is observed along with visible changes in the surfaces of lips and buccal mucosa. Addison's disease can also occur because of preexisting factors such as tuberculosis, histoplasmosis, coccidioiodomycosis , autoimmune diseases and conditions associated with bilateral metastases, hemorrhages, amyloidosis and adrenoleukodystrophy.

Diagnosis of Addison's disease

Addison's disease is diagnosed by clinical symptoms which are correlated with biochemical laboratory tests. The levels of sodium, potassium and other important parameters with respect to inflammatory response and hormonal levels can diagnose the presence of Addison's disease. One of the significant diagnostic tools used to detect the presence of Addison's disease is the ACTH (adrenocorticotropic hormone stimulation test). In this test, ACTH is given intravenously to the patient and the levels of cortisol in urine and blood are examined. This test determines adrenal insufficiency factor.

Addison's disease and pregnancy

Steroid hormone balance and support aids labor and fetal development. Insufficiency of steroid hormones can affect the pregnancy especially during a cesarian. Conditions associated with Addison's disease may increase under situations of emergency. This is because of lack of steroid production in the body. Symptoms such as colds, confusion, increased weakness and fatigue can occur; which may become fatal if untreated.

Diet for Addison's disease

Patients with Addison's disease express cravings for salty food or foods that have citrus flavor. Sufficient intake of proteins balanced with vitamins and minerals is advisable. Many patients suffer dehydration; hence increased fluid intake is advised. Diet patterns can be altered in patients having conditions such as diabetes, hypertension and osteoporosis.

Treatment for Addison's disease

Hydrocortisone and fludrocortisone are generally used to replace the cortisol and aldosterone hormones in cases of adrenal insufficiency. Other options used are prednisone, dexamethasone with slow and sustained release characteristics. The advisable dosage for these steroid hormones is thrice a day to meet with the energy demands and activity of the individual.

Aldosterone test

Aldosterone test maesures the level of aldosterone hormone in the blood. Aldosterone performs the task of maintaining optimal levels of sodium and potassium in the blood by maintaining water balance and blood volume. Elevated levels of aldosterone are indicative of aldosteronism or hyperaldosteronism. The presence of a tumor may bring about high levels of aldosterone. Low levels of aldosterone may suggest diabetes or Addison's disease. Pregnant women may notice high values of aldosterone in the blood.

Medications such as corticosteroids, diuretics, female hormones and hypertension drugs can affect the results of aldosterone test. Even the body posture can affect aldosterone levels in the blood. The amount of salt consumed can cause changes in blood aldosterone levels. Aldosterone test is conducted to study any possible overactivity of adrenal glands. Aldosterone test is conducted on a blood sample or 24 hour urine sample. Normal aldosterone range for urine is 2-80 mg/24 hr. Typical blood aldosterone range is 3-10 ng/dL when the patient is in supine position and 5 - 20 ng/dL when sitting upright.