Tests
1st tests to order
morning serum cortisol
Test
The blood sample should preferably be drawn between 8 a.m. and 9 a.m., when cortisol levels peak.
Cortisol values vary according to the assay used, and use of the reference ranges provided by the relevant laboratory is recommended.[4]
Cortisol level >10 micrograms/dL is considered normal in someone who is not stressed.
A level below 5 micrograms/dL is suggestive of adrenal insufficiency.[2]
If there is considerable suspicion of adrenal insufficiency but morning cortisol levels are high, the use of synthetic glucocorticoids (e.g., hydrocortisone, methylprednisolone, prednisone) within the 12 hours preceding the test should be determined as these drugs cross-react with the cortisol assay.[8]
Serum cortisol is 80% bound to cortisol-binding globulin (CBG) and 10% to 15% to albumin, so disorders that affect CBG levels or albumin influence cortisol levels.[2] Conditions associated with hypoalbuminemia (malnutrition; nephrotic syndrome) may result in lower levels of measured cortisol, while free cortisol levels may be normal. Conditions that are associated with increased CBG lead to false elevation in serum cortisol level. Such conditions include instances where estrogen is increased such as the use of oral contraceptives, estrogen replacement therapy, or pregnancy. Other conditions that also lead to increased CBG and consequently false elevation in serum cortisol include liver disease (e.g., hepatitis).[2][8]
In an emergency situation, the physician should not wait for the results of blood tests before administering treatment. In this situation, blood is drawn for paired cortisol and adrenocorticotropic hormone levels if diagnosis is not known, and treatment administered immediately.[26]
Result
<5 micrograms/dL
plasma adrenocorticotropic hormone (ACTH)
Test
Sample should be collected simultaneously with morning serum cortisol for adequate interpretation.
Normal levels (20 to 52 picograms/mL) exclude primary adrenal insufficiency (PAI).[9]
It is important to interpret the value of plasma ACTH level within the context of the prevailing serum cortisol concentration. An elevated plasma ACTH (more than twofold over the upper limit of the normal range) associated with a low serum cortisol makes the diagnosis of PAI highly likely.[3][9]
Plasma should be kept on ice after being drawn and immediately sent to the laboratory for analysis.[27]
If the result of the test is inconsistent with the clinical picture, technical aspects of collection and interpretation of the examination should be checked.
Result
>52 picograms/mL
serum electrolytes
Test
Not routinely required but helpful for diagnosis.
Deficiency in glucocorticoids and mineralocorticoids leads to changes in fluid and electrolyte balance and the finding of low sodium and high potassium serum levels is typical.[2][4]
In an emergency situation, the physician should not wait for the results of blood tests before administering treatment. In this situation, blood is drawn for paired cortisol and adrenocorticotropic hormone levels if diagnosis is not known, and treatment administered immediately.[26]
Result
low sodium; elevated potassium; rarely, elevated calcium
BUN and creatinine
Test
Deficiency of glucocorticoids and mineralocorticoids and the resultant volume depletion may lead to an elevated BUN and creatinine.[2][26]
In an emergency situation, the physician should not wait for the results of blood tests before administering treatment. In this situation, blood is drawn for paired cortisol and adrenocorticotropic hormone levels if diagnosis is not known, and treatment administered immediately.[26]
Result
may be elevated
CBC
Test
Deficiency of glucocorticoids and mineralocorticoids results in changes in blood count (anemia, eosinophilia, lymphocytosis).[2][4]
In an emergency situation, the physician should not wait for the results of blood tests before administering treatment. In this situation, blood is drawn for paired cortisol and adrenocorticotropic hormone levels if diagnosis is not known, and treatment administered immediately.[26]
Result
anemia, eosinophilia, relative lymphocytosis, and neutropenia
Tests to consider
adrenocorticotropic hormone (ACTH) stimulation test
Test
Also known as short corticotropin stimulation test and high-dose cosyntropin/cortrosyn stimulation test.
Should be ordered when morning serum cortisol does not confirm or exclude adrenal insufficiency.
The test can be performed at any time of the day.[2]
Most normal individuals have cortisol levels above 18 micrograms/dL at 30 and/or 60 minutes after intravenous or intramuscular ACTH 250 micrograms.[8] The optimal values need to be individualized depending on the assay used, as newer assays require lower threshold to reduce false positive test results.[29]
The sensitivity depends on the degree of adrenal insufficiency. Patients with mild or early disease may respond with adequate increase in cortisol levels after ACTH stimulation.[31]
Using 1 microgram of ACTH, compared with 250 micrograms, has been suggested as more sensitive in identifying adrenal hypofunction. A meta-analysis has concluded that the high-dose and low-dose ACTH stimulation tests are satisfactory for indicating the presence of secondary adrenal insufficiency but data in primary adrenal insufficiency are insufficient to estimate diagnostic accuracy, such that neither was reliable for consistently encoding the disorder.[32]
Result
serum cortisol <18 micrograms/dL
plasma renin activity
Test
In patients with primary adrenal insufficiency (PAI), the entire adrenal cortex is involved, and biosynthesis of aldosterone is compromised in addition to that of cortisol. To compensate, renin levels become elevated, but they are ineffective. A low plasma aldosterone associated with a high simultaneously measured plasma renin activity is indicative of PAI.[2][4]
In contrast, in secondary adrenal insufficiency, the renin-angiotensin-aldosterone axis is intact, although slightly less responsive as a consequence of suppressed cortisol concentrations.
Result
elevated
serum aldosterone
Test
In patients with primary adrenal insufficiency (PAI), the entire adrenal cortex is involved, and biosynthesis of aldosterone is compromised in addition to that of cortisol. A low plasma aldosterone associated with a high simultaneously measured plasma renin activity is indicative of PAI.[2][4]
May help to differentiate PAI from secondary adrenal insufficiency.
Result
suppressed
serum dehydroepiandrosterone (DHEA) and DHEA sulfate (DHEA-S)
Test
In patients with primary adrenal insufficiency (PAI), the entire adrenal cortex is involved, and androgen biosynthesis is compromised in addition to that of cortisol and aldosterone. Adrenal androgens (DHEA, DHEA-S) are usually the first to be lost when adrenal cortical function is impaired.[2][27] Levels below the lower limit of normal for age and sex are a useful initial sign of PAI, but cannot be used alone to make the diagnosis because levels may be low, especially in older age, without PAI.[2]
Serum DHEA and DHEA-S concentrations are consistently suppressed in both PAI and central (secondary or tertiary) adrenal failure.
Measurement of serum DHEA levels during the stimulation tests improves the diagnostic accuracy of the test.[34]
Result
suppressed
adrenal antibodies
Test
Autoimmune adrenalitis is the most common cause of adult cases of primary adrenal insufficiency (PAI).[2] Antibodies directed against the adrenal enzyme 21-hydroxylase are associated with autoimmune PAI, but although sensitive they are not necessary for the diagnosis.[2][4][35]
Patients with other autoimmune diseases, such as type 1 diabetes, rheumatoid arthritis, vitiligo, or Hashimoto thyroiditis, may develop autoantibodies against the adrenal cortex. However, the development of clinical adrenal insufficiency does not occur consistently.
Result
may be present
adrenal CT or MRI
Test
Should only be requested after biochemical diagnosis has been confirmed.
In some patients after diagnosis of primary adrenal insufficiency, the underlying cause is still uncertain. Imaging of the adrenals using CT and MRI can be useful where infection, hemorrhage, or metastatic disease is suspected.[4]
Patients with autoimmune adrenalitis may have normal or atrophic adrenal glands on imaging.
Enlarged adrenals, with or without calcifications, suggest infectious, hemorrhagic, or metastatic disease, although normal adrenals can be seen during the initial period of infectious disease.[39][40]
Result
commonly normal or atrophic adrenals; may be enlarged with or without calcifications
insulin hypoglycemia test
Test
Test of the entire hypothalamic-pituitary-adrenal (HPA) axis.[28][36] Vigilance is required, due to the fact that hypoglycemia is an endpoint. The test is contraindicated in older adults and in people with cardiovascular disease or seizure disorder.
The test is rarely indicated as a diagnostic test for adrenal insufficiency and should be performed under the supervision of an experienced endocrinologist.
Result
abnormal in primary or secondary adrenal insufficiency
overnight single-dose metyrapone test
Test
Test of the entire hypothalamic-pituitary-adrenal (HPA) axis.[28][37]
Particularly useful where cortisol response to adrenocorticotropic hormone may be normal in the presence of HPA dysfunction if secondary adrenal insufficiency is suspected.
The test is not indicated in patients suspected of having primary adrenal insufficiency.
The main limitation to using this test is its limited availability for routine testing. There is limited availability of metyrapone in the US; it can be obtained via a specialist pharmacy. In many countries, metyrapone is available through its manufacturer.
Care is required since there is a risk of precipitating adrenal insufficiency, because metyrapone blocks a step in cortisol synthesis.[9]
Result
abnormal in primary or secondary adrenal insufficiency
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