And It's About Time There Was Some Support For Cushing's!
From the Merck Manual
Other Pituitary Gland Disorders
The pituitary
gland, a pea-sized gland at the base of the brain, produces a number of hormones. (see illustration,
left. Click on the thumbnail for a larger image) Several of these hormones, such as corticotropin, thyroid-stimulating hormone, follicle-stimulating
hormone, and luteinizing hormone, control the function of other endocrine glands and stimulate these glands to produce other hormones.
Growth hormone, another pituitary hormone, ensures growth during childhood.
Inadequate pituitary function is called hypopituitarism. In children, hypopituitarism may be caused by a noncancerous pituitary tumor (craniopharyngioma), an injury, or an infection, or it may have no identifiable cause (idiopathic hypopituitarism). Rarely, hypopituitarism (and diabetes insipidus) occurs as part of Hand-Schüller-Christian disease, which affects small areas of bone and lungs and the function of the pituitary gland.
If the pituitary gland malfunctions before puberty, growth is delayed, sexual characteristics do not develop, and the thyroid and adrenal glands function inadequately. After puberty, pituitary malfunction can cause decreased sex drive, impotence, and shrinking of the testes.
In panhypopituitarism, the production of all pituitary hormones decreases or stops. This disorder can result when the entire pituitary gland is damaged.
Sometimes only one pituitary hormone is missing. For example, if only luteinizing hormone is missing (isolated luteinizing hormone deficiency), the testes develop and produce sperm, because these functions are controlled by follicle-stimulating hormone, but the testes do not produce enough testosterone. Testosterone is the hormone that stimulates the development of male secondary sexual characteristics, such as deepening of the voice, growth of facial hair, and maturation of the penis. Consequently, boys who have isolated luteinizing hormone deficiency do not develop these characteristics. Abnormally long arms and legs may be another symptom of this deficiency.
Growth hormone may also be deficient. In pituitary dwarfism, the pituitary gland produces inadequate amounts of growth hormone, which cause abnormally slow growth and short stature with normal proportions. Most short children, however, have normally functioning pituitary glands and are short because their growth spurt is late or their parents are relatively short.
The symptoms of inadequate pituitary function vary depending on which hormone is deficient. For example, growth may be impaired and mental development may be poor in children who lack thyroid-stimulating hormone.
The age at which the deficiencies start also influences which symptoms develop. The effects on a fetus are different from those on a newborn or an older child.
If inadequate pituitary function seems likely, a doctor orders blood tests to measure hormone levels. Measuring the level of growth hormone is not always useful or indicative of a deficiency because the body produces the hormone in short bursts that cause its level to rise and fall quickly. To look for a deficiency of growth hormone, a doctor can measure the level of insulin-like growth factor I (IGF-I). Some pituitary hormones are measured directly; others are measured repeatedly over 1 to 2 hours after a specific stimulus is given by mouth or by injection. X-rays of the hand may be performed to determine bone age, which indicates whether the bones are still growing and how much longer they are likely to grow. A computed tomography (CT) scan or magnetic resonance imaging (MRI) of the head may detect a tumor or other structural abnormality in or near the pituitary gland.
Children deficient in a particular pituitary hormone can be given an identical synthetic hormone as replacement. For instance, children who are short because of a deficiency of growth hormone can be given synthetic growth hormone. They may grow 4 to 6 inches in the first year of treatment; subsequent growth is slower. Growth hormone replacement is not appropriate for short children who have normal levels of growth hormone. New treatments that stimulate the body's natural production of growth hormone are being investigated.
Either the missing pituitary hormone or the hormone that is dependent on the pituitary hormone can be replaced. The latter approach is generally preferred. For example, a child who cannot produce thyroid-stimulating hormone is given thyroid hormone. Testosterone is given to a boy who cannot produce follicle-stimulating hormone and luteinizing hormone, and estrogen is given to a girl who cannot produce these two hormones.
| Hormone | Target Organ |
|---|---|
| Antidiuretic hormone | Kidney |
| Beta-melanocyte-stimulating hormone | Skin |
| Corticotropin | Adrenal glands |
| Endorphins | Brain |
| Enkephalins | Brain |
| Follicle-stimulating hormone | Ovaries or testes |
| Growth hormone | Muscles and bones |
| Luteinizing hormone | Ovaries or testes |
| Oxytocin | Uterus and mammary glands |
| Prolactin | Mammary glands |
| Thyroid-stimulating hormone | Thyroid gland |
