Adrenal hypofunction, also called adrenal insufficiency, may be classified as primary or secondary. Primary adrenal hypofunction (Addison’s disease) originates within the adrenal gland and is characterized by decreased mineralocorticoid, glucocorticoid, and androgen secretion. A relatively uncommon disorder, Addison’s disease occurs in people of all ages and both sexes. Adrenal hypofunction may also occur secondary to a disorder outside the gland, such as with a pituitary tumor with corticotropin deficiency, but, unlike the primary form, aldosterone secretion remains unaffected.

With early diagnosis and adequate replacement therapy, the prognosis for both forms of adrenal hypofunction is promising.

Adrenal crisis—also called addisonian crisis—is a critical deficiency of mineralocorticoids and glucocorticoids that generally follows acute stress, sepsis, trauma, surgery, or the discontinuation of steroid therapy. Adrenal crisis is a medical emergency that necessitates immediate, vigorous treatment.

Cushing’s syndrome is the clinical manifestation of glucocorticoid (particularly cortisol) excess. Excess secretions of mineralocorticoids and androgens may also cause Cushing’s syndrome. In about 70% of patients, Cushing’s syndrome results from excess production of corticotropin and consequent hyperplasia of the adrenal cortex.

The disorder is classified as primary, secondary, or iatrogenic, depending on its cause, and is most common in females.

The hallmark signs of Cushing’s syndrome include adiposity of the face, neck, and trunk, and purple striae on the skin. The nature of the prognosis depends largely on early diagnosis, identification of the underlying cause, and effective treatment.

A disorder of water metabolism, diabetes insipidus results from a deficiency of circulating vasopressin (also called antidiuretic hormone, or ADH), a resistance to vasopressin at the receptor sites in the kidneys, or an abnormal thirst mechanism. A decrease in ADH levels leads to altered intracellular and extracellular fluid control, causing renal excretion of a large amount of urine. Diabetes insipidus can strike people of all ages, from infancy to adulthood.

In uncomplicated diabetes insipidus and with adequate water replacement, the prognosis is good and patients usually can lead normal lives. However, in cases complicated by an underlying disorder, such as cancer, the prognosis is variable.

Diabetes mellitus is a chronic disease of absolute or relative insulin deficiency or resistance. It’s characterized by disturbances in carbohydrate, protein, and fat metabolism. Insulin deficiency compromises the body tissues’ ability to access essential nutrients for fuel and storage.

Diabetes mellitus occurs in two primary forms: type 1, characterized by absolute insufficiency; and the more prevalent type 2, characterized by insulin resistance with varying degrees of insulin secretory defects.

Onset of type 1 usually occurs before age 30, although it may occur at any age. type 2 usually occurs in obese adults after age 40; however, it’s becoming more common in North American youths.

Diabetes mellitus is thought to affect about 7% of the population of the United States (24 million people); about 6 million cases are undiagnosed. Incidence is essentially the same between males and females and increases with age.

In type 1 diabetes, pancreatic beta-cell destruction or primary defect in beta-cell function results in a failure to release insulin and ineffective glucose transport. Type 1 immune-mediated diabetes is caused by cell-mediated destruction of pancreatic beta cells. In type 2 diabetes, beta cells release insulin, but receptors resist insulin, glucose transport is variable and ineffective.

Thyroid hormone overproduction results in the metabolic imbalance hyperthyroidism, which is also called thyrotoxicosis.

The most common form is Graves’ disease, which increases thyroxine (T₄) production, enlarges the thyroid gland (goiter), and causes multiple systemic changes. Incidence of Graves’ disease is highest between ages 30 and 40, especially in people with family histories of thyroid abnormalities; only 5% of hyperthyroid patients are younger than age 15. With treatment, most patients can lead normal lives.

However, thyrotoxic crisis (or thyroid storm), an acute exacerbation of hyperthyroidism, is a medical emergency that can lead to life-threatening cardiac, hepatic, or renal failure.