Hypopituitarism is an endocrine disorder characterized by a decreased secretion of one or more of the pituitary hormones.
The pituitary is a small pea shaped gland present at the base of the brain, behind the nose, and is connected to the hypothalamus. It is a major endocrine gland that regulates the functions of other glands. The pituitary, through the release of hormones, regulates various functions of the body such as growth, development, blood pressure, metabolism and reproduction. Any injury or disease of the pituitary gland can affect the entire endocrine system. Any impairment in the normal function of any endocrine gland may have an impact on the entire body resulting in a life-threatening disorder or lifelong disability.
The hormones released by the pituitary gland include:
ACTH (Adrenocorticotropic hormone): ACTH stimulates the adrenal gland to release cortisol hormone that is involved in the regulation of blood sugar and blood pressure.
TSH (Thyroid stimulating hormone): TSH stimulates the production of thyroid hormones from the thyroid gland that regulate metabolism and also impact the growth and development of the body.
GH (Growth hormone): GH regulates the normal growth and development of the bones and tissues.
ADH (Anti-diuretic hormone): ADH regulates the body water balance, through the kidneys.
FSH (Follicle stimulating hormone) and LH (Luteinizing hormone): These hormones regulate the sexual function and fertility in males and females.
Prolactin hormone: This regulates the development of female breasts and production of breast milk.
Oxytocin: It stimulates uterine contractions during delivery as well as the release of milk from the breast.
Any dysfunction of one or more of these hormones may cause hypopituitarism with a dysfunctioning of the respective glands or organs.
Causes of Hypopituitarism
Hypopituitarism is usually caused by a tumour of the pituitary gland. A progression in the size of the tumour may compress and damage the pituitary tissue and hamper the production of hormones. The tumour may also compress the optic nerve resulting in visual disturbance. Other causes of hypopituitarism include head injury, brain surgery, cranial haemorrhage, brain tumours, radiation therapy, stroke or inadequate blood supply to the brain, infection of the brain tissues such as meningitis, tuberculosis and sarcoidosis (an inflammatory disease characterized by scarring in different parts of the body such as the lungs and lymph nodes). Certain genetic mutations and damage to the pituitary gland during childbirth may also cause hypopituitarism.
Symptoms of Hypopituitarism
The onset of the symptoms is usually gradual, and may be unnoticed for months or years. Sometime the symptoms develop suddenly requiring immediate medical attention. The symptoms of hypopituitarism depend on the deficiency of the respective hormone and the severity of the deficiency. Some of the symptoms of hypopituitarism include fatigue, weight loss, sensitivity to cold, decreased appetite, infertility, sexual impairment, loss of libido, loss of body and facial hair in men, inability to produce milk for breast feeding, loss of pubic hair and irregular menstrual cycles in women. The growth and development in children may be hampered resulting in a short stature. Sometimes a sudden onset of hypopituitarism may cause severe headache, visual disturbance, sudden drop in blood pressure or confusion. This is a medical emergency and requires immediate medical attention.
Diagnosis of Hypopituitarism
The diagnosis of hypopituitarism includes a medical history and blood test such as ACTH test, TSH and T4 test, GH stimulation test, FSH and LH or oestradiol or testosterone test to determine the levels and the deficiencies of the respective hormones. Other imaging studies including CT scan, MRI or X-ray of the brain may be used for detecting any physical abnormalities or tumour of the pituitary gland. X-rays of the hand and wrist help evaluate normal growth of bones in children. Vision tests may also be conducted to evaluate the impact of the pituitary tumour on vision.
Treatment of Hypopituitarism
Treatment of hypopituitarism depends on the underlying cause responsible for the hormone deficiency and comprises of hormone replacement therapy along with treatment of the underlying cause. Hormone replacement therapy involves supplementation of the deficient hormone to the patient and includes corticosteroid, thyroid replacement, testosterone or oestrogen replacement therapy and growth hormone replacement therapy. These medications replace the deficient hormone and may help suppress the symptoms. Regular follow up visits with your doctor are essential to monitor your condition and adjust the dose of your hormone replacement therapy accordingly. Surgery and/or radiation therapy may be required for the management of the pituitary tumour. Radiation therapy may be used to shrink the tumour while surgical treatment may be used to remove the tumour from the body.