To assist in the investigation of adrenocortical dysfunction using ACTH and cortisol levels in diagnosing disorders such as Addison disease, Cushing disease, and Cushing syndrome.
There are no food or fluid restrictions unless by medical direction. Drugs that enhance steroid metabolism may be withheld by medical direction before metyrapone stimulation testing. Instruct the patient to refrain from smoking, avoid alcohol use, avoid strenuous exercise for 12 hr before the test, and remain in bed or at rest for 1 hr immediately before the test. Samples should be collected at the same time of day, between 0600 and 0800.
|Procedure||Indications||Medication Administered, Adult Dosage||Recommended Collection Times|
|ACTH stimulation, rapid test||Suspect adrenal insufficiency (Addison disease) or congenital adrenal hyperplasia||1 mcg (low-dose physiological protocol) cosyntropin intramuscular (IM) or IV; 250 mcg (standard pharmacological protocol) cosyntropin IM or IV||Three cortisol levels: Baseline immediately before bolus, 30 min after bolus, and 60 min (optional) after bolus. Baseline and 30-min levels are adequate for accurate diagnosis using either dosage; low-dose protocol sensitivity is most accurate for 30-min level only.|
|Corticotropin-releasing hormone (CRH) stimulation||Differential diagnosis between ACTH-dependent conditions such as Cushing disease (pituitary source) or Cushing syndrome (ectopic source) and ACTH-independent conditions such as Cushing syndrome (adrenal source)||IV dose of 1 mcg/kg human CRH||Eight cortisol and eight ACTH levels: Baseline collected 15 min before injection, 0 min before injection, and then 5, 15, 30, 60, 120, and 180 min after injection|
|Dexamethasone suppression (overnight)||Differential diagnosis between ACTH-dependent conditions such as Cushing disease (pituitary source) or Cushing syndrome (ectopic source) and ACTH-independent conditions such as Cushing syndrome (adrenal source)||Oral dose of 1 mg dexamethasone (Decadron) at 2300||Cortisol level at 0800 on the morning after the dexamethasone dose|
|Metyrapone stimulation (overnight)||Suspect hypothalamic/pituitary disease such as adrenal insufficiency, ACTH-dependent conditions such as Cushing disease (pituitary source) or Cushing syndrome (ectopic source), and ACTH-independent conditions such as Cushing syndrome (adrenal source)||Oral dose of 30 mg/kg metyrapone (up to a maximum of 3 g) with snack at 2400||Cortisol, 11-deoxycortisol, and ACTH at 0800 on the morning after the metyrapone dose|
Method: Immunochemiluminescent assay for ACTH and cortisol; high-performance liquid chromatography tandem mass spectrometry (LC-MS/MS) for 11-deoxycortisol.
|Age||Conventional Units||SI Units (Conventional Units × 0.22)|
|Cord blood||50–570 pg/mL||11–125 pmol/L|
|Newborn||10–185 pg/mL||2–41 pmol/L|
|1 wk–9 yr||5–46 pg/mL||1.1–10.1 pmol/L|
|10–18 yr||6–55 pg/mL||1.3–12.1 pmol/L|
|Male supine (specimen collected in morning)||7–69 pg/mL||1.5–15.2 pmol/L|
|Female supine (specimen collected in morning)||6–58 pg/mL||1.3–12.8 pmol/L|
|Values may be unchanged or slightly elevated in healthy older adults. Long-term use of corticosteroids, to treat arthritis and autoimmune diseases, may suppress secretion of ACTH.|
ACTH Challenge Tests
|ACTH (Cosyntropin) Stimulated, Rapid Test||Conventional Units||SI Units (Conventional Units × 27.6)|
|Baseline||Cortisol greater than 5 mcg/dL||Greater than 138 nmol/L|
|30- or 60-min response||Cortisol 18–20 mcg/dL or incremental increase of 7 mcg/dL over baseline value||497–552 nmol/L or incremental increase of 193.2 nmol/L over baseline value|
|Corticotropin-Releasing Hormone Stimulated||Conventional Units||SI Units (Conventional Units × 27.6)|
|Cortisol peaks at greater than 20 mcg/dL within 30–60 min||Greater than 552 nmol/L|
|SI Units (Conventional Units × 0.22)|
|ACTH increases twofold to fourfold within 30–60 min||Twofold to fourfold increase within 30–60 min|
|Dexamethasone Suppressed Overnight Test||Conventional Units||SI Units (Conventional Units × 27.6)|
|Cortisol less than 1.8 mcg/dL next day||Less than 49.7 nmol/L|
|Metyrapone Stimulated Overnight Test||Conventional Units||SI Units (Conventional Units × 27.6)|
|Cortisol less than 3 mcg/dL next day||Less than 83 nmol/L|
|SI Units (Conventional Units × 0.22)|
|ACTH greater than 75 pg/mL||Greater than 16.5 pmol/L|
|SI Units (Conventional Units × 28.9)|
|11-deoxycortisol greater than 7 mcg/dL||Greater than 202 nmol/L|
|Salivary Cortisol||Conventional Units|
|1500–1700||Less than 401 ng/dL|
|2300–midnight||Less than 100 ng/dL|
|24 hr Urine Free Cortisol by Age||Conventional Units|
|3–8 yr||1.4–20 mcg/24 hr|
|9–12 yr||2.6–37 mcg/24 hr|
|13–17 yr||4–56 mcg/24 hr|
|18 yr–adult||3.5–45 mcg/24 hr|
Critical Findings and Potential Interventions
Hypothalamic-releasing factor stimulates the release of ACTH from the anterior pituitary gland. ACTH stimulates adrenal cortex secretion of glucocorticoids, androgens, and, to a lesser degree, mineralocorticoids. Cortisol is the major glucocorticoid secreted by the adrenal cortex. ACTH and cortisol test results are evaluated together because a change in one normally causes a change in the other.
Cortisol levels vary diurnally, with the peak values occurring between 0600 and 0800 and reaching the lowest levels between 2000 and 2400. Specimens are typically collected at 0800 and 1600. This pattern may be reversed in individuals who sleep during daytime hours and are active during nighttime hours. Cortisol excess from any source is termed Cushing syndrome. Three studies are recommended for assisting in the diagnosis of Cushing syndrome: late night (2300) salivary cortisol, 24-hr urine free cortisol, and overnight dexamethasone suppression test. Cortisol excess resulting from ACTH excess produced by the pituitary is termed Cushing disease. Salivary cortisol levels are known to parallel blood levels and can be used to screen for Cushing disease and Cushing syndrome.
ACTH levels exhibit a diurnal variation, peaking between 0600 and 0800 and reaching the lowest point between 1800 and 2300. Evening levels are generally one-half to two-thirds lower than morning levels. ACTH secretion is stimulated by insulin, metyrapone, and vasopressin. It is decreased by dexamethasone.
The metyrapone stimulation test is contraindicated in patients with suspected adrenal insufficiency because it may induce an acute adrenal crisis, a life-threatening condition, in patients whose adrenal function is already compromised.
Factors that may alter the results of the study
Rapid clearance of metyrapone, resulting in falsely increased cortisol levels, may occur if the patient is taking drugs that enhance steroid metabolism (e.g., corticosteroids, mitotane, phenytoin, phenobarbital, and rifampin). The requesting health-care provider (HCP) should be consulted prior to a metyrapone stimulation test regarding a decision to withhold these medications.
Metyrapone may cause gastrointestinal distress and/or confusion. Administer oral dose of metyrapone with milk and snack.
Because ACTH and cortisol secretion exhibit diurnal variation with values being highest in the morning, a lack of change in values from morning to evening is clinically significant. Decreased concentrations of hormones secreted by the pituitary gland and its target organs are observed in hypopituitarism. In primary adrenal insufficiency (Addison disease), because of adrenal gland destruction by tumor, infectious process, or immune reaction, ACTH levels are elevated, while cortisol levels are decreased. Both ACTH and cortisol levels are decreased in secondary adrenal insufficiency (i.e., secondary to pituitary insufficiency). Excess ACTH can be produced ectopically by various lung cancers such as oat-cell cancer and large-cell cancer of the lung and by benign bronchial carcinoid tumor.
Challenge Tests and Results
The ACTH (cosyntropin) stimulated rapid test directly evaluates adrenal gland function and indirectly evaluates pituitary gland and hypothalamus function. Cosyntropin is a synthetic form of ACTH. A baseline cortisol level is collected before the injection of cosyntropin. Specimens are subsequently collected at 30- and 60-min intervals. If the adrenal glands function normally, cortisol levels rise significantly after administration of cosyntropin.
The CRH stimulation test works as well as the dexamethasone suppression test (DST) in distinguishing Cushing disease from conditions in which ACTH is secreted ectopically (e.g., tumors not located in the pituitary gland that secrete ACTH). Patients with pituitary tumors tend to respond to CRH stimulation, whereas those with ectopic tumors do not. Patients with adrenal insufficiency demonstrate one of three patterns depending on the underlying cause:
(The DST is useful in differentiating the causes of increased cortisol levels. Dexamethasone is a synthetic glucocorticoid that is significantly more potent than cortisol. It works by negative feedback. It suppresses the release of ACTH in patients with a normal hypothalamus. A cortisol level less than 1.8 mcg/dL [SI = 49.7 nmol/L] usually excludes Cushing syndrome. With the DST, a baseline morning cortisol level is collected, and the patient is given a 1-mg dose of dexamethasone at bedtime. A second specimen is collected the following morning. If cortisol levels have not been suppressed, adrenal adenoma is suspected. The DST also produces abnormal results in the presence of certain psychiatric illnesses [e.g., endogenous depression]).
The metyrapone stimulation test is used to distinguish corticotropin-dependent causes (pituitary Cushing disease and ectopic Cushing disease) from corticotropin-independent causes (e.g., cancer of the lung or thyroid) of increased cortisol levels. Metyrapone inhibits the conversion of 11-deoxycortisol to cortisol. Cortisol levels should decrease to less than 3 mcg/dL if normal pituitary stimulation by ACTH occurs after an oral dose of metyrapone. Specimen collection and administration of the medication are performed as with the overnight dexamethasone test.
Overproduction of ACTH can occur as a direct result of either disease (e.g., primary or ectopic tumor that secretes ACTH) or stimulation by physical or emotional stress, or it can be an indirect response to abnormalities in the complex feedback mechanisms involving the pituitary gland, hypothalamus, or adrenal glands.
ACTH Increased in
Secondary adrenal insufficiency due to hypopituitarism (inadequate production by the pituitary) can result in decreased levels of ACTH. Conditions that result in overproduction or availability of high levels of cortisol can also result in decreased levels of ACTH.
ACTH Decreased in
|Summary of the Relationship Between Cortisol and ACTH Levels in Conditions Affecting the Adrenal and Pituitary Glands|
|Disease||Cortisol Level||ACTH Level|
|Addison disease (adrenal insufficiency)||Decreased||Increased|
|Cushing disease (pituitary adenoma)||Increased||Increased|
|Cushing syndrome related to ectopic source of ACTH||Increased||Increased|
|Cushing syndrome (ACTH independent; adrenal cancer or adenoma)||Increased||Decreased|
|Congenital adrenal hyperplasia||Decreased||Increased|
Potential Nursing Problems Assessment and Nursing Diagnosis
|Problems||Signs and Symptoms|
|Fluid volume (excess) (related to retention of sodium and water secondary to cortisol excess)||Weight gain, hypertension, tachycardia, edema, jugular vein distention, shortness of breath; abnormal blood gas results|
|Infection (related to impaired immune response secondary to elevated cortisol level, collagen tissue loss, catabolism of peripheral tissues)||Delayed wound healing, inhibited collagen formation, impaired blood flow to edematous tissues, symptoms of infection (temperature, increased heart rate, increased blood pressure, shaking, chills, mottled skin, lethargy, fatigue, swelling, edema, pain, localized pressure, diaphoresis, night sweats, confusion, vomiting, nausea, headache)|
|Injury (related to poor wound healing, decreased bone density, capillary fragility)||Easy bruising, blood in stool, skin breakdown, fracture, poor wound healing, thin skin|
|Mobility (related to change in muscle and bone structure secondary to excess cortisol)||Fatigue, muscle weakness, porous bones with fracture risk|
Teaching the Patient What to Expect
Potential Nursing Actions
Followup Evaluation and Desired Outcomes
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