A pituitary disease is any disorder that occurs due to a dysfunction or malfunction of the pituitary gland. The pea-sized pituitary gland is part of the endocrine system that secretes the hormones prolactin, adrenocorticotropin (ACTH), growth hormone (GH), antidiuretic hormone (ADH), thyroid-stimulating hormone (TSH), luteinizing hormone (LH), and follicle-stimulating hormone (FSH). When there is overproduction or underproduction of these pituitary hormones, a pituitary disease or disorder results. Overproduction pituitary diseases include acromegaly, syndrome of inappropriate antidiuretic hormone (SIADH), and pituitary adenoma. Underproduction pituitary diseases include growth hormone deficiency, diabetes insipidus, Sheehan syndrome, and hypopituitarism.
Acromegaly is a pituitary disease wherein a tumor in the gland produces an excessive growth hormone. The tumor is rare and not cancerous. Acromegaly refers to the enlargement of bones among people whose epiphyseal plates have closed, leading to severe disfigurement, arthritis, hypertension, and heart and kidney failure. When excessive growth hormone levels are produced among persons whose epiphyses have not yet closed, such as in children and adolescents, the disorder is called gigantism.
Growth hormone deficiency is at the other end of the spectrum. It typically manifests as an increase in body fat and cholesterol, a decrease in muscle mass and bone mass, a reduction of stamina, and excessive tiredness. Growth hormone deficiency may be due to a pituitary tumor or as a consequence of a pituitary tumor treatment, such as surgery or radiotherapy.
SIADH occurs due to the overproduction of ADH. ADH helps control the water and sodium levels of the body by preventing water loss through the urine. Excessive ADH levels causes the body to retain water, leading to fluid overload and hyponatremia, or low sodium levels. Diabetes insipidus is due to insufficient levels of ADH. When it occurs, the kidneys cannot retain water, leading to feelings of dryness, excessive thirstiness, and a frequent need to urinate.
When a pituitary adenoma or tumor does not secrete any of the hormones, it is called a nonfunctioning adenoma. Usually, a nonfunctioning pituitary adenoma is only detected when a person experiences visual impairment, headaches, and abnormal eye movements, which occur due to the adenoma compressing the second and third cranial nerves. Other effects include loss of appetite, loss of libido, erectile dysfunction, irregular menstruation, infertility, and fatigue.
Sheehan syndrome is a unique pituitary disease because it only occurs among women who have just given birth. It is also called postpartum pituitary necrosis or postpartum hypopituitarism. Blood loss and shock may occur during and after giving birth, leading to an insufficient blood supply to the pituitary gland, finally resulting in death or necrosis of the gland. The result is hypopituitarism that manifests as lack of lactation or agalactorrhea, irregular or absent menstruation, hypothyroidism, cold or heat intolerance, weight gain, hair loss, and constipation. These are symptoms secondary to the lack of stimulation of the thyroid gland, reproductive organs, and adrenal glands by the hormones normally secreted by the pituitary gland.
