An unsung hero

By: Dr Peter Hall

There are some organs in the body that don’t get enough credit – when was the last time you thought about your pituitary gland, for example? 

I can tell you that, despite its anonymity, none of us would be alive without it. It’s only the size of a pea and nestles quietly at the base of the brain. Its traditional title was “conductor of the endocrine orchestra”, but really it is more like first violin, being bossed around by the hypothalamus which sits just above it. Flowing out from, or through, the pituitary are hormones that affect the adrenal glands, ovaries and testes, the thyroid, kidneys, uterus and the breasts. It also generates growth hormone.

Pituitary tumours are not uncommon and some don’t cause any problems at all but, if they grow too large, pressure on the adjacent optic nerves can result in visual problems. The gland is really hard to access surgically and the best approach is through the nose and sphenoid sinuses which strikes me as incredibly clever. 

In general practice the pituitary problems we see are:
Prolactinoma – a benign tumour that generates too much prolactin – the hormone that stimulates breast milk production. Most are controlled with medication.
Cushing’s disease – once again a benign tumour, but this time producing ACTH which overstimulates the adrenal glands and causes symptoms like a prolonged overdose of steroids. Generally this needs surgery.
Craniopharyngioma – this is a puzzling condition where cells left over from embryonic development overgrow. This is a slow process so symptoms may develop anywhere between childhood and old age. Unfortunately the whole gland has to be removed, so afterwards the patient has to have all the pituitary hormones replaced and balanced for the rest of their life. 

Rarely, the pituitary can be underactive due to infection, trauma, haemorrhage or an autoimmune process.

If we include the hypothalamus, then disorders are rare. However there can be a problem with over or underproduction of ADH. ADH, or vasopressin,  switches off urine production, especially at night. It is sometimes given to children to reduce bedwetting. There are a number of medical conditions that can cause too much ADH, in which case the body will  retain fluid, or not enough, so the patient has huge urine output and thirst. The latter is called diabetes insipidus, not to be confused with diabetes mellitus which is due to reduced insulin production in the pancreas.

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