Although over 40,000 people in the UK are thought to suffer from pituitary disorders, many of the illnesses are little known outside specialist clinics. The commonest disorders of the pituitary are adenomas, benign (non-cancerous) tumours which, if left untreated, may expand very slowly over a period of several years. Pituitary adenomas can cause symptoms through overproduction of one of the pituitary hormones and, if sufficiently large, from pressure on other brain structures close by.
Overproduction of growth hormone, for example, in children causes excessive growth, a condition known as gigantism. Adults developing a growth hormone-secreting pituitary adenoma develop a condition known as acromegaly, characterised by enlargement of the hands and feet, and coarsening of facial features.
Prolactinomas, benign pituitary tumours overproducing prolactin, cause menstrual disturbances (typically infrequent or absent periods), galactorrhoea (milk leakage from the breasts) and fertility problems in women, while in men the commonest symptoms are reduced libido and erectile dysfunction.
Excessive secretion of ACTH results in a condition called Cushing's disease. There is overstimulation of the adrenal glands, resulting in excess steroid production. This has many different effects including weight gain, with a 'moon face' appearance, thinning of the skin, stretch marks, easy bruising, muscle weakness, and high blood pressure.
Some pituitary tumours are 'non-functioning' and only produce symptoms when large enough to cause pressure on adjacent structures. This can result in headache, visual disturbance (as the pituitary lies in close proximity to the optic nerves) and under-activity of the surrounding normal pituitary gland; a condition known as hypopituitarism.
Hypopituitarism may be partial or complete and its effects depend on which of the pituitary hormones are affected. TSH deficiency, for example, results in symptoms of thyroid underactivity, with fatigue (tiredness), lethargy, cold intolerance, a tendency to weight gain, constipation, dry skin and hair and impaired memory. Symptoms associated with glucocorticoid (steroid) deficiency resulting from a lack of ACTH include weakness, tiredness and fatigue, dizziness or light-headedness on standing (resulting from reduced blood pressure). Lack of LH and FSH in women causes the periods to stop and impaired fertility while, in men, the resulting lack of testosterone causes reduced libido (sex drive) and erectile dysfunction, reduced muscle.