This tiny brain gland conducts our ‘hormonal orchestra’, and issues can arise if its action is impaired. Dr Mel Wynne-Jones reveals six tests you might need
Our pea-sized pituitary glands are located deep behind the bridge of our noses at the base of our brains.
They produce nine different hormones that control various body functions; these are monitored and adjusted by a nearby brain area, the hypothalamus.
If, for example, our hypothalamus detects that our thyroid gland isn’t producing enough thyroid hormone (thyroxine), it sends TRH (thyrotrophin-releasing hormone) to our pituitary, which releases more TSH (thyroid stimulating hormone) and makes our thyroid step up production.
This feedback loop also ensures that when we’ve made enough thyroxine, our hypothalamus switches off TRH until it next detects more thyroxine is needed. Pituitary symptoms may be mixed or unusual, especially if more than one hormone is affected (see below).
What can go wrong?
Each hormone has its own feedback loop, constantly adjusting levels to our needs.
But a pituitary tumour (growth) may boost levels of one or more stimulating hormones, although some may actually fall (pituitary failure) if nearby cells get squashed.
Levels may also rise if the ‘target organ’ (for example, the thyroid) isn’t responding. Pituitary tumours are almost always benign (non-cancerous) but as they grow they can also cause headaches, or press on nearby nerves, impairing vision.
Pituitary failure can also occur after major childbirth haemorrhage.
The pituitary produces ADH (antidiuretic hormone), which tells the kidneys to excrete less water.
Too much causes fluid retention and high blood pressure; too little causes frequent urination, thirst and dehydration.
It also produces oxytocin, important for labour and breast-milk release. The pituitary controls our thyroid glands; too much TSH speeds our bodies up, while too little slows everything down.
It also sends ACTH (adrenocorticotropic hormone) to our adrenal glands; these make cortisol (our ‘fright, flight or fight’ hormone), which also affects our blood sugar, blood pressure, immune system and suppresses inflammation.
Too much ACTH leads to Cushing’s syndrome (weight gain, red ‘moon’ face, high blood pressure); too little produces Addison’s disease (low blood pressure, chemical abnormalities and extreme fatigue).
The pituitary also produces growth hormone (which controls growth and repair, including our muscle/fat balance) and melanocyte stimulating hormone (for skin pigment/colour).
Too much growth hormone produces acromegaly (excessive height, large hands, feet, tongue and a deep voice); too little stunts growth.
The sex hormones LH (luteinising hormone) and FSH (follicle stimulating hormone) are also produced in the pituitary – these control our ovaries (and testicular function in men).
High or low levels can affect menstruation and fertility; hot flushes and sweats are triggered by surges in LH/FSH when our menopausal ovaries stop responding. High levels of the ninth hormone, prolactin, can stimulate inappropriate breast-milk production.
Tumours can be treated with surgery, radiotherapy or suppressant drugs; you may also need treatment or supplements for high/low levels of various hormones, before, after and/or instead of removal.
But as more of us have brain scans for various reasons, more pituitary microadenomas are being detected; these tiny benign tumours may not need treatment, unless they grow or rock the hormone boat. But you’ll need regular monitoring and adjustment of treatment, especially if you are planning a pregnancy.
But you’ll need regular monitoring and adjustment of treatment, especially if you are planning a pregnancy.
4 tests you may need
1. A range of blood tests to measure how your pituitary, hypothalamus and various body organs/functions are working.
2. A skull X-ray – this may show pressure on skull bones from a growing pituitary tumour.
3. Eye tests – you may not be able to see things at the side or top of each eye’s field of vision.
4. A magnetic resonance (MR) brain scan.