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).

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.

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.

In endocrinology, medical emergencies include diabetic ketoacidosis, hyperosmolar hyperglycemic state, hypoglycemic coma, acute adrenocortical insufficiency, phaeochromocytoma crisis, hypercalcemic crisis, thyroid storm, myxoedema coma and pituitary apoplexy.

Emergencies arising from decompensated pheochromocytomas or parathyroid adenomas are sometimes referred for emergency resection when aggressive medical therapies fail to control the patient's state, however the surgical risks are significant, especially blood pressure lability and the possibility of cardiovascular collapse after resection (due to a brutal drop in respectively catecholamines and calcium, which must be compensated with gradual normalization). It remains debated when emergency surgery is appropriate as opposed to urgent or elective surgery after continued attempts to stabilize the patient, notably in view of newer and more efficient medications and protocols.

Endocrine diseases are disorders of the endocrine system. The branch of medicine associated with endocrine disorders is known as endocrinology.

Acanthosis nigricans should be distinguished from the casal collar appearing in pellagra.

Pituitary incidentalomas are pituitary tumors that are characterized as an incidental finding. They are often discovered by computed tomography (CT) or magnetic resonance imaging (MRI), performed in the evaluation of unrelated medical conditions such as suspected head trauma, in cancer staging or in the evaluation of nonspecific symptoms such as dizziness and headache. It is not uncommon for them to be discovered at autopsy. In a meta-analysis, adenomas were found in an average of 16.7% in postmortem studies, with most being microadenomas (<10mm); macrodenomas accounted for only 0.16% to 0.2% of the decedents. While non-secreting, noninvasive pituitary microadenomas are generally considered to be literally as well as clinically benign, there are to date scant studies of low quality to support this assertion.

It has been recommended in the current Clinical Practice Guidelines (2011) by the Endocrine Society - a professional, international medical organization in the field of endocrinology and metabolism - that all patients with pituitary incidentalomas undergo a complete medical history and physical examination, laboratory evaluations to screen for hormone hypersecretion and for hypopituitarism. If the lesion is in close proximity to the optic nerves or optic chiasm, a visual field examination should be performed. For those with incidentalomas which do not require surgical removal, follow up clinical assessments and neuroimaging should be performed as well follow-up visual field examinations for incidentalomas that abut or compress the optic nerve and chiasm and follow-up endocrine testing for macroincidentalomas.

Acanthosis nigricans is typically diagnosed clinically. A skin biopsy may be needed in unusual cases. If no clear cause is obvious, it may be necessary to search for one. Blood tests, an endoscopy, or X-rays may be required to eliminate the possibility of diabetes or cancer as the cause.

On biopsy, hyperkeratosis, epidermal folding, leukocyte infltration, and melanocyte proliferation may be seen.

The diagnosis of primary hyperparathyroidism is made by blood tests.

Serum calcium levels are elevated, and the parathyroid hormone level is abnormally high compared with an expected low level in response to the high calcium. A relatively elevated parathyroid hormone has been estimated to have a sensitivity of 60%-80% and a specificity of approximately 90% for primary hyperparathyroidism.

A more powerful variant of comparing the balance between calcium and parathyroid hormone is to perform a 3-hour calcium infusion. After infusion, a parathyroid hormone level above a cutoff of 14 ng/l has a sensitivity of 100% and a specificity of 93% in detecting primary hyperparathyroidism, with a confidence interval of 80% to 100%.

Urinary cAMP is occasionally measured; this is generally elevated.

Biochemical confirmation of primary hyperparathyroidism is following by investigations to localize the culprit lesion. Primary hyperparathyroidism is most commonly due to solitary parathyroid adenoma. Less commonly it may be due to double parathyroid adenomas or parathyroid hyperplasia. Tc99 sestamibi scan of head, neck and upper thorax is the most commonly used test for localizing parathyroid adenomas having a sensitivity and specificity of 70-80%. Sensitivity falls down to 30% in case of double/multiple parathyroid adenomas or in case of parathyroid hyperplasia. Ultrasonography is also a useful test in localizing suspicious parathyroid lesions.

An adrenal "incidentaloma" is an adrenal tumor found by coincidence without clinical symptoms or suspicion. It is one of the more common unexpected findings revealed by computed tomography (CT), magnetic resonance imaging (MRI), or ultrasonography.

In these cases, a dexamethasone suppression test is often used to detect cortisol excess, and metanephrines or catecholamines for excess of these hormones. Tumors under 3 cm are generally considered benign and are only treated if there are grounds for a diagnosis of Cushing's syndrome or pheochromocytoma. Radiodensity gives a clue in estimating malignancy risk, wherein a tumor with 10 Hounsfield units or less on an unenhanced CT is probably a lipid-rich adenoma.

Hormonal evaluation includes:

- 1-mg overnight dexamethasone suppression test

- 24-hour urinary specimen for measurement of fractionated metanephrines and catecholamines

- Blood plasma aldosterone concentration and plasma renin activity, "if hypertension is present"

On CT scan, benign adenomas typically are of low radiographic density (due to fat content) and show rapid washout of contrast medium (50% or more of the contrast medium washes out at 10 minutes). If the hormonal evaluation is negative and imaging suggests benign, followup should be considered with imaging at 6, 12, and 24 months and repeat hormonal evaluation yearly for 4 years

Hypothalamic disease is a disorder presenting primarily in the hypothalamus, which may be caused by damage resulting from malnutrition, including anorexia and bulimia eating disorders, genetic disorders, radiation, surgery, head trauma, lesion, tumour or other physical injury to the hypothalamus. The hypothalamus is the control center for several endocrine functions. Endocrine systems controlled by the hypothalamus are regulated by anti-diuretic hormone (ADH), corticotropin-releasing hormone, gonadotropin-releasing hormone, growth hormone-releasing hormone, oxytocin, all of which are secreted by the hypothalamus. Damage to the hypothalamus may impact any of these hormones and the related endocrine systems. Many of these hypothalamic hormones act on the pituitary gland. Hypothalamic disease therefore affects the functioning of the pituitary and the target organs controlled by the pituitary, including the adrenal glands, ovaries and testes, and the thyroid gland.

Numerous dysfunctions manifest as a result of hypothalamic disease. Damage to the hypothalamus may cause disruptions in body temperature regulation, growth, weight, sodium and water balance, milk production, emotions, and sleep cycles. Hypopituitarism, neurogenic diabetes insipidus, tertiary hypothyroidism, and developmental disorders are examples of precipitating conditions caused by hypothalamic disease.

Unlike tumors of the posterior Pituitary, Pituitary adenomas are classified as endocrine tumors (not brain tumors). Pituitary adenomas are classified based upon anatomical, histological and functional criteria.

- Anatomically pituitary tumors are classified by their size based on radiological findings; either microadenomas (less than <10 mm) or macroadenomas (equal or greater than ≥10 mm).

- Histological classification utilizes an immunohistological characterization of the tumors in terms of their hormone production. Historically they were classed as either basophilic, acidophilic, or chromophobic on the basis of whether or not they took up the tinctorial stains hematoxylin and eosin. This classification has fallen into disuse, in favor of a classification based on what type of hormone is secreted by the tumor. Approximately 20-25% of adenomas do not secrete any readily identifiable active hormones ('non-functioning tumors') yet they are still sometimes referred to as 'chromophobic'.

- Functional classification is based upon the tumors endocrine activity as determined by serum hormone levels and pituitary tissue cellular hormone secretion detected via immunohistochemical staining. The "Percentage of hormone production cases" values are the fractions of adenomas producing each related hormone of each tumor type as compared to all cases of pituitary tumors, and does not directly correlate to the percentages of each tumor type because of smaller or greater incidences of absence of secretion of the expected hormone. Thus, nonsecretive adenomas may be either "null cell adenomas" or a more specific adenoma that, however, remains nonsecretive.

The spectrum of gynecomastia severity has been categorized into a grading system:

- Grade I: Minor enlargement, no skin excess

- Grade II: Moderate enlargement, no skin excess

- Grade III: Moderate enlargement, skin excess

- Grade IV: Marked enlargement, skin excess

Early histological features expected to be seen on examination of gynecomastic tissue attained by fine-needle aspiration biopsy include the following: proliferation and lengthening of the ducts, an increase in connective tissue, an increase in inflammation and swelling surrounding the ducts, and an increase in fibroblasts in the connective tissue. Chronic gynecomastia may show different histological features such as increased connective tissue fibrosis, an increase in the number of ducts, less inflammation than in the acute stage of gynecomastia, increased subareolar fat, and hyalinization of the stroma. When surgery is performed, the gland is routinely sent to the lab to confirm the presence of gynecomastia and to check for tumors under a microscope. The utility of pathologic examination of breast tissue removed from male adolescent gynecomastia patients has recently been questioned due to the rarity of breast cancer in this population.

Several trials investigated a possible therapy for ESS. However, they yielded inconsistent and partly contradictory results. This may be caused by the fact that the investigated populations were too heterogeneous in the lack of a consistent definition of "non-thyroid illness syndrome".

Modern theories regard the TACITUS syndrome as an adaptive and therefore possibly beneficial response of thyroid homeostasis. Their proponents are therefore reserved with respect to substitutive treatment.

Affected patients may have normal, low, or slightly elevated TSH depending on the spectrum of illness. Total T4 and T3 levels may be altered by binding protein abnormalities, and medications. Reverse T3 levels are generally increased signifying inhibition of normal type 1 deiodinase or reduced clearance of reverse T3. Correspondingly, in the majority of cases calculated sum activity of peripheral deiodinases (SPINA-GD) is reduced. Generally the levels of free T3 will be lowered, followed by the lowering of free T4 in more severe disease. Several studies described elevated concentrations of 3,5-T2, an active thyroid hormone, in NTIS. 3,5-T2 levels were also observed to correlate with concentrations of rT3 (reverse T3) in patients with euthyroid sick syndrome.

TACITUS syndrome is a component of a complex endocrine adaptation process. Therefore, affected patients might also have hyperprolactinemia and elevated levels of corticosteroids (especially cortisol) and growth hormone.

The hypothalamus and pituitary gland are tightly integrated. Damage to the hypothalamus will impact the responsiveness and normal functioning of the pituitary. Hypothalamic disease may cause insufficient or inhibited signalling to the pituitary leading to deficiencies of one or more of the following hormones: thyroid-stimulating hormone, adrenocorticotropic hormone, beta-endorphin, luteinizing hormone, follicle-stimulating hormone, and melanocyte–stimulating hormones. Treatment for hypopituitarism involves hormone replacement therapy.

Treatment is usually surgical removal of the gland(s) containing adenomas, but medication may also be required.

Endocrine disorder is more common in women than men, as it is associated with menstrual disorders.

Management of MEN2 patients includes thyroidectomy including cervical central and bilateral lymph nodes dissection for MTC, unilateral adrenalectomy for unilateral pheochromocytoma or bilateral adrenalectomy when both glands are involved and selective resection of pathologic parathyroid glands for primary hyperparathyroidism.

Familial genetic screening is recommended to identify at risk subjects who will develop the disease, permitting early management by performing prophylactic thyroidectomy, giving them the best chance of cure.

Prognosis of MEN2 is mainly related to the stage-dependant prognosis of MTC indicating the necessity of a complete thyroid surgery for index cases with MTC and the early thyroidectomy for screened at risk subjects.

Besides the clinical picture, fasting VIP plasma level may confirm the diagnosis, and CT scan and somatostatin receptor scintigraphy are used to localise the tumor, which is usually metastatic at presentation.

Tests include:

- Blood chemistry tests (basic or comprehensive metabolic panel)

- CT scan of the abdomen

- MRI of the abdomen

- Stool examination for cause of diarrhea and electrolyte levels

- Vasoactive intestinal peptide (VIP) level in the blood

Treatment modality depends on the cause. Tumors may be removed surgically, but pituitary stalk interruption may persist. Usually, replacement of those hormones that are reduced due to failed feedback control systems will be necessary.

A recommend surveillance program for Multiple Endocrine Neoplasia Type 1 has been suggested by the International Guidelines for Diagnosis and Therapy of MEN syndromes group.

In terms of diagnosis for this condition, the following methods/tests are available:

- Endoscopic

- CT scan

- Serum endocrine autoantibody screen

- Histologic test