17. - ENDOCRINE SYSTEM DISORDERS

17. - EN

17. - ENDOCRINE SYSTEM DISORDERS

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

TYPES OF ENDOCRINE DISEASE

Broadly speaking, endocrine disorders may be subdivided into three groups:

1. Endocrine gland hyposecretion (leading to hormone deficiency)
2. Endocrine gland hypersecretion (leading to hormone excess)
3. Tumours (benign or malignant) of endocrine glands

Endocrine disorders are often quite complex, involving a mixed picture of hyposecretion and hypersecretion because of the feedback mechanisms involved in the endocrine system. For example, most forms of hyperthyroidism are associated with an excess of thyroid hormone and a low level of thyroid stimulating hormone.

PITUITARY GLAND DISORDERS

Posterior pituitary

• Diabetes insipidus

Anterior pituitary

• Hypopituitarism (or Panhypopituitarism)

• Pituitary tumors
• Pituitary adenomas
• Prolactinoma (or Hyperprolactinemia)
• Acromegaly, gigantism
• Cushing's disease

 

GIGANTISM:

Gigantism, also known as giantism (from Greek γίγας gigas, "giant", plural γίγαντες gigantes), is a condition characterized by excessive growth and height significantly above average. In humans, this condition is caused by over-production of growth hormone^[1] in childhood before the long bone epiphyses closes resulting in persons between 7 feet (2.13 m) and 9 feet (2.74 m) in height.
Many of those who have been identified with gigantism have suffered from multiple health problems involving their circulatory or skeletal system.

 

ACROMEGALY

Is a syndrome that results when the anterior pituitary gland produces excess growth hormone (GH) after epiphyseal plate closure at puberty. A number of disorders may increase the pituitary's GH output, although most commonly it involves a GH-producing tumor called pituitary adenoma, derived from a distinct type of cell (somatotrophs).

Acromegaly most commonly affects adults in middle age, and can result in severe disfigurement, serious complicating conditions, and premature death if unchecked. Because of its pathogenesis and slow progression, the disease is hard to diagnose in the early stages and is frequently missed for many years, until changes in external features, especially of the face, become noticeable.
Acromegaly is often also associated with gigantism.

Causes

 

 

Pituitary adenoma

In over 90 percent of acromegaly patients, the overproduction of growth hormones is caused by a benign tumor of the pituitary gland, called an adenoma. These tumors produce excess growth hormones and, as they expand, compress surrounding brain tissues, such as the optic nerves. This expansion causes the headaches and visual disturbances that often accompany acromegaly. In addition, compression of the surrounding normal pituitary tissue can alter production of other hormones, leading to changes in menstruation and breast discharge in women and impotence in men because of reduced testosterone production.
There is a marked variation in rates of GH production and the aggressiveness of the tumor. Some adenomas grow slowly and symptoms of growth hormone excess are often not noticed for many years. Other adenomas grow rapidly and invade surrounding brain areas or the sinuses, which are located near the pituitary. In general, younger patients tend to have more aggressive tumors.
Most pituitary tumors arise spontaneously and are not genetically inherited. Many pituitary tumors arise from a genetic alteration in a single pituitary cell which leads to increased cell division and tumor formation. This genetic change, or mutation, is not present at birth, but is acquired during life. The mutation occurs in a gene that regulates the transmission of chemical signals within pituitary cells; it permanently switches on the signal that tells the cell to divide and secrete growth hormones. The events within the cell that cause disordered pituitary cell growth and growth hormone oversecretion currently are the subject of intensive research.

HYPERTHYROIDISM
Hyperthyroidism, often referred to as an 'overactive thyroid', is when the thyroid  gland produces and secretes excessive amounts of the free - not protein bound and circulating in

the blood - thyroid hormones, triiodothyronine (T3) and/or thyroxine (T4). This is the opposite of hypothyroidism ('sluggish thyroid'), which is the reduced production and secretion of T3 and/or T4. Hyperthyroidism is a type of thyrotoxicosis, a hypermetabolic clinical syndrome which occurs when there are elevated serum levels of T3 and/or T4. Graves disease is the most common form of hyperthyroidism.

 While hyperthyroidism may cause thyrotoxicosis they are not synonymous medical conditions; some patients may develop thyrotoxicosis as a result of inflammation of the thyroid gland (thyroiditis), which may cause the release of excessive thyroid hormone already stored in the gland but does not cause accelerated hormone production. Thyrotoxicosis may also occur by the ingestion of excessive amounts of exogenous thyroid hormone in the form of thyroid hormone supplements such as the most widely used supplement Levothyroxine, liothyronine, in weight-reducing dietary supplements that contain thyroid hormone, synthetic forms of T4 and T3 or thyroid extract (desiccated thyroid). Excessive exogenous intake may be purposeful as part of various treatment regimens such as to suppress tumor growth in thyroid cancer or inadvertently, as in when using dietary supplements or via percutaneous absorption, as a result of topical use of cosmetic creams containing iodine or thyroid hormones.^] In these cases it is termed Thyrotoxicosis Factitia (L, facticius :artificial or self-induced); it is also known by other terms such as exogenous thyrotoxicosis, alimentary thyrotoxicosis or occult factitial thyrotoxicosis.
Disease management and therapy differ for thyrotoxicosis caused by hyperthyroidism and thyrotoxicosis caused by other conditions. Thyroid imaging and radiotracer thyroid uptake measurements, combined with serologic data, enable specific diagnosis and appropriate patient treatment.

CUSHING SYNDROME

Cushing syndrome is a disorder that occurs when your body is exposed to high levels of the hormone cortisol. It may also occur if you take too much cortisol or other steroid hormones.

Causes

Cushing syndrome may be caused by taking too much corticosteroid medications, such as prednisone and prednisolone. These drugs are used to treat conditions such as asthma and rheumatoid arthritis.

Other people develop Cushing syndrome because their bodies produce too much cortisol, a hormone normally made in the adrenal gland. Causes of too much cortisol are:

• Cushing's disease, when the pituitary gland makes too much of the hormone ACTH. ACTH then signals the adrenal glands to produce cortisol. Tumor of the pituitary gland may cause this condition.
• Tumor of the adrenal gland
• Tumor elsewhere in the body that produces cortisol
• Tumors elsewhere in the body that produce ACTH (such as the pancreas, lung, and thyroid).