Professor Howard Jacobs

Pituitary hormones are released in response to instruction from the Hypothalamus, in the brain. The hormones sent by the hypothalamus are Thyrotrophin-releasing hormone for stimulation of thyroid-stimulating hormone (TSH) release, corticotrophin-releasing hormone for Adrenocorticotrophic Hormone (ACTH), Growth hormone-releasing hormone for growth hormone (GH) and gonadotrophin-releasing hormone (GnRH) for Luteinising hormone (LH) and Follicle-stimulating hormone (FSH). Prolactin is produced independently by the pituitary, and its control is by inhibition from the hypothalamus. Hypopituitarism can be of varying degrees, affecting one or more hormones. If all hormone production is lost it is termed pan-hypopituitarism.

The most common functioning Pituitary tumour is a Prolactinoma, caused by a benign collection of cells. Prolactin is made in excess, so switching off the production of LH / FSH. In the male this reduces testicular function, so decreasing sexual function and potency, whilst in the female there is absence of periods, reducing production of Oestrogen and varying degrees of breast milk production. Osteoporosis is a major long-term risk, especially in women, because they lose the protective effects of oestrogen. Bone density scans should be undertaken at diagnosis and then at intervals until bone density is in the correct range for age and sex.

Thyroid function can be affected by failure of TSH production. Tests can differentiate between pituitary and thyroid causes of thyroid dysfunction. If thyroid function tests are inconclusive a trial of Thyroxine may be used to measure symptomatic response.

Failure of GH production can lead to Short stature in children, and early treatment with recombinant GH will ensure a return to normal growth and height. In adults, under-production of GH leads to adult GH deficiency syndrome, diagnosed by biochemical results and symptomatic complaints. It is estimated that symptoms occur in about 50% of GH-deficient patients. Treatment with recombinant GH restores and helps maintain muscle strength and well-being.

Lack of LH / FSH affects the fertility of both sexes. In women there is a lack of menstruation and low production of oestrogen. The main long-term effect of oestrogen deficiency is osteoporosis. To prevent this, hormone replacement therapy should provide enough oestrogen to give withdrawal bleeds. If the condition pre-exists puberty, it is important for replacement therapy to be given at a pace and dose that mimic the natural development pattern of puberty.

For male patients, Testosterone replacement should be provided to preserve muscle bulk, secondary sex characteristics and normal sexual function. In the adult male, testosterone should begin at low dose, building to a maintenance dose over a period of time. This allows adjustment to the emotional effects of testosterone. For the male child, replacement therapy should promote puberty at a normal pace, reaching adult maintenance doses after around 5 years. Testosterone is not responsible for sperm production; an adult male needs human chorionic gonadotrophin, and perhaps FSH, two or three times a week to promote spermatogenesis. This will also encourage self-production of testosterone.

The Adrenal glands produce Cortisol (a hormone which is more essential to life than others), aldosterone (a salt-retaining hormone) and Androgens. These are male hormones that are normally over-balanced in women by ovarian function and in men by testicular function. In hypopituitarism, a lack of ACTH reduces androgen production which, for females, is a main source of testosterone. This leads to an absence of secondary sex hair. Recent studies have also found that a lack of androgens can effect well-being.

Due to a large amount of interest from the floor, there was unfortunately not enough time to cover the role and replacement of cortisol.