The best diagnostic tool to confirm adrenal insufficiency is the ACTH stimulation test; however, if a patient is suspected to be suffering from an acute adrenal crisis, immediate treatment with IV corticosteroids is imperative and should not be delayed for any testing, as the patient's health can deteriorate rapidly and result in death without replacing the corticosteroids.

Dexamethasone should be used as the corticosteroid if the plan is to do the ACTH stimulation test at a later time as it is the only corticosteroid that will not affect the test results.

If not performed during crisis, then labs to be run should include: random cortisol, serum ACTH, aldosterone, renin, potassium and sodium. A CT of the adrenal glands can be used to check for structural abnormalities of the adrenal glands. An MRI of the pituitary can be used to check for structural abnormalities of the pituitary. However, in order to check the functionality of the Hypothalamic Pituitary Adrenal (HPA) Axis the entire axis must be tested by way of ACTH stimulation test, CRH stimulation test and perhaps an Insulin Tolerance Test (ITT). In order to check for Addison’s Disease, the auto-immune type of primary adrenal insufficiency, labs should be drawn to check 21-hydroxylase autoantibodies.

In suspected cases of Addison's disease, demonstration of low adrenal hormone levels even after appropriate stimulation (called the ACTH stimulation test or synacthen test) with synthetic pituitary ACTH hormone tetracosactide is needed for the diagnosis. Two tests are performed, the short and the long test. It should be noted that dexamethasone does not cross-react with the assay and can be administered concomitantly during testing.

The short test compares blood cortisol levels before and after 250 micrograms of tetracosactide (intramuscular or intravenous) is given. If, one hour later, plasma cortisol exceeds 170 nmol/l and has risen by at least 330 nmol/l to at least 690 nmol/l, adrenal failure is excluded. If the short test is abnormal, the long test is used to differentiate between primary adrenal insufficiency and secondary adrenocortical insufficiency.

The long test uses 1 mg tetracosactide (intramuscular). Blood is taken 1, 4, 8, and 24 hr later. Normal plasma cortisol level should reach 1000 nmol/l by 4 hr. In primary Addison's disease, the cortisol level is reduced at all stages, whereas in secondary corticoadrenal insufficiency, a delayed but normal response is seen.

Other tests may be performed to distinguish between various causes of hypoadrenalism, including renin and adrenocorticotropic hormone levels, as well as medical imaging - usually in the form of ultrasound, computed tomography or magnetic resonance imaging.

Adrenoleukodystrophy, and the milder form, adrenomyeloneuropathy, cause adrenal insufficiency combined with neurological symptoms. These diseases are estimated to be the cause of adrenal insufficiency in about 35% of male patients with idiopathic Addison’s disease, and should be considered in the differential diagnosis of any male with adrenal insufficiency. Diagnosis is made by a blood test to detect very long chain fatty acids.

Growth hormone deficiency is almost certain if all other pituitary tests are also abnormal, and insulin-like growth factor 1 (IGF-1) levels are decreased. If this is not the case, IGF-1 levels are poorly predictive of the presence of GH deficiency; stimulation testing with the insulin tolerance test is then required. This is performed by administering insulin to lower the blood sugar to a level below 2.2 mmol/l. Once this occurs, growth hormone levels are measured. If they are low despite the stimulatory effect of the low blood sugars, growth hormone deficiency is confirmed. The test is not without risks, especially in those prone to seizures or are known to have heart disease, and causes the unpleasant symptoms of hypoglycemia. Alternative tests (such as the growth hormone releasing hormone stimulation test) are less useful, although a stimulation test with arginine may be used for diagnosis, especially in situations where an insulin tolerance test is thought to be too dangerous. If GH deficiency is suspected, and all other pituitary hormones are normal, two different stimulation tests are needed for confirmation.

If morning cortisol levels are over 500 nmol/l, ACTH deficiency is unlikely, whereas a level less than 100 is indicative. Levels between 100-500 require a stimulation test. This, too, is done with the insulin tolerance test. A cortisol level above 500 after achieving a low blood sugar rules out ACTH deficiency, while lower levels confirm the diagnosis. A similar stimulation test using corticotropin-releasing hormone (CRH) is not sensitive enough for the purposes of the investigation. If the insulin tolerance test yields an abnormal result, a further test measuring the response of the adrenal glands to synthetic ACTH (the ACTH stimulation test) can be performed to confirm the diagnosis. Stimulation testing with metyrapone is an alternative. Some suggest that an ACTH stimulation test is sufficient as first-line investigation, and that an insulin tolerance test is only needed if the ACTH test is equivocal. The insulin tolerance test is discouraged in children. None of the tests for ACTH deficiency are perfect, and further tests after a period of time may be needed if initial results are not conclusive.

Symptoms of diabetes insipidus should prompt a formal fluid deprivation test to assess the body's response to dehydration, which normally causes concentration of the urine and increasing osmolarity of the blood. If these parameters are unchanged, desmopressin (an ADH analogue) is administered. If the urine then becomes concentrated and the blood osmolarity falls, there is a lack of ADH due to lack of pituitary function ("cranial diabetes insipidus"). In contrast, there is no change if the kidneys are unresponsive to ADH due to a different problem ("nephrogenic diabetes insipidus").

The diagnosis of hypopituitarism is made on blood tests. Two types of blood tests are used to confirm the presence of a hormone deficiency: basal levels, where blood samples are taken–usually in the morning–without any form of stimulation, and dynamic tests, where blood tests are taken after the injection of a stimulating substance. Measurement of ACTH and growth hormone usually requires dynamic testing, whereas the other hormones (LH/FSH, prolactin, TSH) can typically be tested with basal levels. There is no adequate direct test for ADH levels, but ADH deficiency can be confirmed indirectly; oxytocin levels are not routinely measured.

Generally, the finding of a combination of a low pituitary hormone together with a low hormone from the effector gland is indicative of hypopituitarism. Occasionally, the pituitary hormone may be normal but the effector gland hormone decreased; in this case, the pituitary is not responding appropriately to effector hormone changes, and the combination of findings is still suggestive of hypopituitarism.

Some people only use Conn's syndrome for when it occurs due to an adrenal adenoma (a type of benign tumor). In practice, however, the terms are often used interchangeably, regardless of the underlying physiology.

Screening may be considered in people with high blood pressure presenting with low blood potassium, high blood pressure that is difficult to treat, other family members with the same condition, or a mass on the adrenal gland.

Measuring aldosterone alone is not considered adequate to diagnose primary hyperaldosteronism. Rather, both renin and aldosterone are measured, and a resultant aldosterone-to-renin ratio is used for case detection. A high aldosterone-to-renin ratio suggests the presence of primary hyperaldosteronism. The diagnosis is made by performing a saline suppression test, ambulatory salt loading test, or fludrocortisone suppression test.

If primary hyperaldosteronism is confirmed biochemically, CT scanning or other cross-sectional imaging can confirm the presence of an adrenal abnormality, possibly an adrenal cortical adenoma (aldosteronoma), adrenal carcinoma, bilateral adrenal hyperplasia, or other less common changes. Imaging findings may ultimately lead to other necessary diagnostic studies, such as adrenal venous sampling, to clarify the cause. It is not uncommon for adults to have bilateral sources of aldosterone hypersecretion in the presence of a nonfunctioning adrenal cortical adenoma, making adrenal venous sampling mandatory in cases where surgery is being considered.

The diagnosis is best accomplished by an appropriately-trained subspecialist, though primary care providers are critical in recognizing clinical features of primary aldosteronism and obtaining the first blood tests for case detection.

Hypoadrenocorticism is often tentatively diagnosed on the basis of history, physical findings, clinical pathology, and, for primary adrenal insufficiency, characteristic electrolyte abnormalities.

- Clinical pathology - Abnormalities may be identified on hematology, biochemistry and urinalysis. Elevated concentrations of potassium (hyperkalemia), and low sodium and chloride values (hyponatremia and hypochloremia) are the classic electrolyte alterations. The sodium/potassium ratio often is <27 (normal is between 27:1 and 40:1) and maybe <20 in animals with primary adrenal insufficiency. However, not all dogs have an abnormal electrolyte ratio during an Addisonian episode.

- ECG - The severity of the ECG abnormalities correlates with the severity of the hyperkalemia. Therefore the ECG can be used to identify and estimate the severity of hyperkalemia and to monitor changes in serum potassium during therapy.

- Diagnostic imaging - Abdominal ultrasound may reveal small adrenal glands, suggesting adrenocortical atrophy. However, finding normal-sized adrenal glands does not rule out hypoadrenocorticism. Rarely, megaesophagus is evident on radiographs.

- ACTH stimulation test - Confirmation requires evaluation of an ACTH stimulation test. Basline plasma cortisol and urine cortisol/Cr ratios are unreliable for confirming the diagnosis. One major diagnostic criterion is abnormally decreased post-ACTH plasma cortisol. Normal plasma cortisol after ACTH stimulation rules out adrenal insufficiency. The only accurate test for hypoadrenocorticism is an ACTH stimulation test.

The ACTH stimulation test does not distinguish between primary and secondary hypoadrenocorticism, or adrenocortical destruction caused by mitotane overdose. Differentiation between primary and secondary hypoadrenocorticism can be made by periodically measuring serum electrolytes, baseline endogenous ACTH, or possibly serum or plasma aldosterone during the ACTH stimulation test. While most corticosteroid drugs will invalidate the results of an ACTH test, dexamethasone may be used in the event of an Addison's emergency without fear of compromising the results of the test.

In general, hypoadrenocorticism is underdiagnosed in dogs, and one must have a clinical suspicion of it as an underlying disorder for many presenting complaints. Females are overrepresented, and the disease often appears in middle age (four to seven years), although any age or gender may be affected. Dogs with hypoadrenocorticism may also have one of several autoimmune disorders. Because it is an endocrine disorder, they may also suffer from neuropathy and some endocrine-related eye diseases.

As with hyperthyroidism, TSH is suppressed. Both free and serum (or total) T3 and T4 are elevated. An elevation in thyroid hormone levels is suggestive of thyroid storm when accompanied by signs of severe hyperthyroidism but is not diagnostic as it may also correlate with uncomplicated hyperthyroidism. Moreover, serum T3 may be normal in critically ill patients due to decreased conversion of T4 to T3. Other potential abnormalities include the following:

- Hyperglycemia likely due to catecholamine-mediated effects on insulin release and metabolism as well as increased glycogenolysis, evolving into hypoglycemia when glycogen stores are depleted

- Elevated aspartate aminotransferase (AST), bilirubin and lactate dehydrogenase (LDH)

- Hypercalcemia and elevated alkaline phosphatase due to increased bone resorption

- Elevated white blood cell count

Routine laboratory investigations may show:

- Hypercalcemia

- Hypoglycemia, low blood sugar (worse in children due to loss of glucocorticoid's glucogenic effects)

- Hyponatremia (low blood sodium levels), due to loss of production of the hormone aldosterone, to the kidney's inability to excrete free water in the absence of sufficient cortisol, and also the effect of corticotropin-releasing hormone to stimulate secretion of ADH.

- Hyperkalemia (raised blood potassium levels), due to loss of production of the hormone aldosterone.

- Eosinophilia and lymphocytosis (increased number of eosinophils or lymphocytes, two types of white blood cells)

- Metabolic acidosis (increased blood acidity), also is due to loss of the hormone aldosterone because sodium reabsorption in the distal tubule is linked with acid/hydrogen ion (H) secretion. Absent or insufficient levels of aldosterone stimulation of the renal distal tubule leads to sodium wasting in the urine and H retention in the serum.

Persistently increased blood pressure may also be due to kidney disease or hyperthyroidism. When a cause is not readily apparent, and especially when hypokalemia is identified, hyperaldosteronism should be considered. Diagnostic imaging, usually beginning with abdominal ultrasound, may identify that one or both adrenal glands are enlarged. Imaging may also detect metastasis and usually includes radiographs of the chest in addition to abdominal ultrasound and/or computerized tomography (CT).

The ratio of plasma aldosterone concentration (PAC) to plasma renin activity (PRA) can be used as a screening test for PHA. In cats with unilateral or bilateral zona glomerulosa tumors, the PAC may be very high while the PRA is completely suppressed. In cats with idiopathic bilateral nodular hyperplasia of the zona glomerulosa, the PAC may be slightly elevated or high normal. In the presence of hypokalemia even a mildly elevated aldosterone should be considered inappropriately high. A high-normal or elevated PAC with a low PRA indicates persistent aldosterone synthesis in the presence of little or no stimulation of the renin-angiotensin system.

The diagnosis of thyroid storm is based on the presence of symptoms consistent with severe hyperthyroidism, as outlined in the Signs and symptoms section above. Multiple approaches have been proposed to calculate the probability of thyroid storm based on clinical criteria, however, none have been universally adopted by clinicians. For instance, Burch and Wartofsky published the Burch-Wartofsky point scale (BWPS) in 1993, assigning a numerical value based on the presence of specific signs and symptoms organized within the following categories: temperature, cardiovascular dysfunction (including heart rate and presence of atrial fibrillation or congestive heart failure), central nervous system (CNS) dysfunction, gastrointestinal or liver dysfunction and presence of a precipitating event. A Burch-Wartofsky score below 25 is not suggestive of thyroid storm whereas 25 to 45 suggests impending thyroid storm and greater than 45 suggests current thyroid storm. Alternatively, the Japanese Thyroid Association (JTA) criteria, derived from a large cohort of patients with thyroid storm in Japan and published in 2012, provide a qualitative method to determine the probability of thyroid storm. The JTA criteria separate the diagnosis of thyroid storm into definite versus suspected based on the specific combination of signs and symptoms a patient exhibits and require elevated free triiodothyronine (T3) or free thyroxine (T4) for definite thyroid storm.

Breeds that began in the Pacific Rim, among them Akitas and Shiba Inus, tend to have higher potassium values in laboratory test, and elevated levels are not abnormal. Dogs who do not have hypoadrenocorticism have normal values on ACTH tests.

Biopsy is the only means of accurate diagnosis as no autoantigen has been discovered. Biopsy of the pituitary gland is not easily performed with safety as it sits under the brain, however, a test does exist to detect antibodies to the pituitary without biopsy: autoantibodies to M(r) 49,000 pituitary cytosolic protein may represent markers for an immunological process affecting the pituitary gland. Tests for normal pituitary gland hormone production tend to be expensive and in some cases difficult to administer. In addition, certain hormone levels vary largely throughout the day and in response to metabolic factors, making abnormal levels difficult to calibrate—further hampering diagnosis.

Hormonal assay : there may be low level of T4, TSH, Estrogen, Gonadotropin, Cortisol and ACTH depending on the extent of necrosis

MRI of the pituitary and hypothalamus: this helps to exclude tumor or other pathologies.

In a study of 1,034 symptomatic adults, Sheehan syndrome was found to be the sixth most frequent etiology of growth hormone deficiency, being responsible for 3.1% of cases (versus 53.9% due to a pituitary tumor).

Secondary refers to an abnormality that indirectly results in pathology through a predictable physiologic pathway, i.e., a renin-producing tumor leads to increased aldosterone, as the body's aldosterone production is normally regulated by renin levels.

One cause is a juxtaglomerular cell tumor. Another is renal artery stenosis, in which the reduced blood supply across the juxtaglomerular apparatus stimulates the production of renin. Likewise, fibromuscular dysplasia may cause stenosis of the renal artery, and therefore secondary hyperaldosteronism. Other causes can come from the tubules: Hyporeabsorption of sodium (as seen in Bartter and Gitelman syndromes) will lead to hypovolemia/hypotension, which will activate the RAAS.

Hypoaldosteronism may result in hyperkalemia and is the cause of 'type 4 renal tubular acidosis', sometimes referred to as hyperkalemic RTA or tubular hyperkalemia. However, the acidosis, if present, is often mild. It can also cause urinary sodium wasting, leading to volume depletion and hypotension.

When adrenal insufficiency develops rapidly, the amount of Na+ lost from the extracellular fluid exceeds the amount excreted in the urine, indicating that Na+ also must be entering cells. When the posterior pituitary is intact, salt loss exceeds water loss, and the plasma Na+ falls. However, the plasma volume also is reduced, resulting in hypotension, circulatory insufficiency, and, eventually, fatal shock. These changes can be prevented to a degree by increasing the dietary NaCl intake. Rats survive indefinitely on extra salt alone, but in dogs and most humans, the amount of supplementary salt needed is so large that it is almost impossible to prevent eventual collapse and death unless mineralocorticoid treatment is also instituted.

Hyponatremia can be caused by glucocorticoid deficiency. Low levels of glucocorticoids leads to systemic hypotension (one of the effects of cortisol is to increase peripheral resistance), which results in a decrease in stretch of the arterial baroreceptors of the carotid sinus and the aortic arch. This removes the tonic vagal and glossopharyngeal inhibition on the central release of ADH: high levels of ADH will ensue, which will subsequently lead to increase in water retention and hyponatremia.

Differently from mineralocorticoid deficiency, glucocorticoid deficiency does not cause a negative sodium balance (in fact a positive sodium balance may occur).

Primary aldosteronism (hyporeninemic hyperaldosteronism) was previously thought to be most commonly caused by an adrenal adenoma, termed Conn's syndrome. However, recent studies have shown that bilateral idiopathic adrenal hyperplasia is the cause in up to 70% of cases. Differentiating between the two is important, as this determines treatment. Also see congenital adrenal hyperplasia.

Adrenal carcinoma is an extremely rare cause of primary hyperaldosteronism.

Two familial forms have been identified: type I (dexamethasone suppressible), and type II (that has been linked to 7p22.)

Features

- Hypertension

- Hypokalemia (e.g., may cause muscle weakness)

- Alkalosis

Investigations

- High serum aldosterone

- Low serum renin

- High-resolution CT abdomen

Management

- Adrenal adenoma: surgery

- Bilateral adrenocortical hyperplasia: aldosterone antagonist, e.g., spironolactone

Unilateral primary hyperaldosteronism due to an adrenocortical adenoma or adrenocarcinoma can be potentially cured surgically. Unilateral adrenalectomy is the treatment of choice for unilateral PHA. Potential complications include hemorrhage and postoperative hypokalemia. With complete removal of the tumor, prognosis is excellent.

Bilateral primary hyperaldosteronism due to hyperplasia of the zona glomerulosa or metastasized adrenocortical adenocarcinoma should be treated medically. Medical therapy is aimed at normalizing blood pressure and plasma potassium concentration. Mineralocorticoid receptor blockers, such as spironolactone, coupled with potassium supplementation are the most commonly used treatments. Specific therapy for treating high blood pressure (e.g., amlodipine), should be added if necessary.

As with other forms of CAH, the primary therapy of 11β-hydroxylase deficient CAH is lifelong glucocorticoid replacement in sufficient doses to prevent adrenal insufficiency and suppress excess mineralocorticoid and androgen production.

Salt-wasting in infancy responds to intravenous saline, dextrose, and high dose hydrocortisone, but prolonged fludrocortisone replacement is usually not necessary. The hypertension is ameliorated by glucocorticoid suppression of DOC.

Long term glucocorticoid replacement issues are similar to those of 21-hydroxylase CAH, and involve careful balance between doses sufficient to suppress androgens while avoiding suppression of growth. Because the enzyme defect does not affect sex steroid synthesis, gonadal function at puberty and long-term fertility should be normal if adrenal androgen production is controlled. See congenital adrenal hyperplasia for a more detailed discussion of androgen suppression and fertility potential in adolescent and adult women.

Various investigations aid the diagnosis.

- ACTH (cosyntropin) stimulation test

- Cortisol level (to assess the level of glucocorticoids)

- Fasting blood sugar

- Serum potassium (to assess the level of mineralocorticoids)

- Serum sodium

Adrenal crisis is triggered by physiological stress (such as trauma). Activities that have an elevated risk of trauma are best avoided. Treatment must be given within two hours of trauma and consequently it is advisable to carry injectable hydrocortisone in remote areas.

Conditions justifying newborn screening for any disorder include (1) a simple test with an acceptable sensitivity and specificity, (2) a dire consequence if not diagnosed early, (3) an effective treatment if diagnosed, and (4) a frequency in the population high enough to justify the expense. In the last decade more states and countries are adopting newborn screening for salt-wasting CAH due to 21-hydroxylase deficiency, which leads to death in the first month of life if not recognized.

The salt-wasting form of CAH has an incidence of 1 in 15,000 births and is potentially fatal within a month if untreated. Steroid replacement is a simple, effective treatment. However, the screening test itself is less than perfect. While the 17α-hydroxyprogesterone level is easy to measure and sensitive (rarely missing real cases), the test has a poorer specificity. Screening programs in the United States have reported that 99% of positive screens turn out to be false positives upon investigation of the infant. This is a higher rate of false positives than the screening tests for many other congenital metabolic diseases.

When a positive result is detected, the infant must be referred to a pediatric endocrinologist to confirm or disprove the diagnosis. Since most infants with salt-wasting CAH become critically ill by 2 weeks of age, the evaluation must be done rapidly despite the high false positive rate.

Levels of 17α-hydroxyprogesterone, androstenedione, and cortisol may play a role in screening.

"Congenital adrenal hyperplasia" (CAH) refers to any of several autosomal recessive diseases resulting from defects in steps of the synthesis of cortisol from cholesterol by the adrenal glands. All of the forms of CAH involve excessive or defective production of sex steroids and can prevent or impair development of primary or secondary sex characteristics in affected infants, children, and adults. Many also involve excessive or defective production of mineralocorticoids, which can cause hypertension or salt wasting, respectively.

The most common type of CAH is due to deficiency of 21-hydroxylase. 11β-Hydroxylase deficient congenital adrenal hyperplasia is one of the less common types of CAH due to deficiencies of other proteins and enzymes involved in cortisol synthesis. Other uncommon types are described in individual articles (links below).

11β-OH CAH resembles 21-hydroxylase deficient CAH in its androgenic manifestations: partial virilization and ambiguous genitalia of genetically female infants, childhood virilization of both sexes, and rarer cases of virilization or infertility of adolescent and adult women. The mineralocorticoid effect differs: hypertension is usually the clinical clue that a patient has 11- rather than 21-hydroxylase CAH. Diagnosis of 11β-OH CAH is usually confirmed by demonstration of marked elevations of 11-deoxycortisol and 11-deoxycorticosterone (DOC), the substrates of 11β-hydroxylase. Management is similar to that of 21-hydroxylase deficient CAH except that mineralocorticoids need not be replaced.