Hypopituitarism: symptoms, causes, tests and hormone replacement

The pituitary gland sits at the base of the brain and makes hormones that are used throughout the body. The Pituitary Foundation explains that if it is damaged or does not function as it should, the hormones may not be produced, leading to hormone deficiencies. "Hypo" means under or below, so hypopituitarism means pituitary hormone levels are below normal. When at least two hormones are deficient it is sometimes called multiple pituitary hormone deficiency.

The Pituitary Foundation lists six hormones that may be affected: growth hormone; luteinising hormone (LH) and follicle-stimulating hormone (FSH), which drive the ovaries and testes; adrenocorticotropic hormone (ACTH), which prompts the adrenal glands to release cortisol; thyroid-stimulating hormone (TSH); arginine vasopressin (AVP, also called antidiuretic hormone), which regulates water; and prolactin. It notes that low prolactin alone does not always mean hypopituitarism.

The Pituitary Foundation says symptoms depend on which hormones are deficient and vary widely in severity. The table sets out the symptoms it lists for each deficiency.

The Pituitary Foundation says there are many possible causes. The most common is a benign tumour in the pituitary gland pressing on the gland. It lists others in the bullets below.

• Surgery or radiotherapy used to treat a pituitary tumour, which can damage the small gland.

• Cysts in the pituitary, such as Rathke's cleft cysts, and benign tumours around the pituitary, such as craniopharyngiomas and meningiomas.

• Serious head injuries. It advises contacting your GP if symptoms such as headaches, feeling sick, poor concentration, tiredness, sleep problems, fertility issues, depression or increased thirst persist for 12 months after a head injury.

• Lack of blood flow or bleeding, including Sheehan's syndrome (severe blood loss during childbirth) and pituitary apoplexy.

• Inflammation of the pituitary (hypophysitis), which is most commonly seen during pregnancy.

• Genetic defects present from birth, infections such as meningitis, and long-term use of some medicines such as glucocorticoids, and some cancer treatments.

The Pituitary Foundation says that if hypopituitarism is suspected you will have blood tests to measure hormone levels. Because many pituitary hormones are highest in the morning, the test is often done first thing in the morning, and sometimes you need to fast for a few hours.

Hormones such as growth hormone usually have levels too low to show on a normal blood test, so you may need a stimulation test, which stimulates the body to release growth hormone and then measures how much is released. For AVP deficiency, urine tests may also be used.

The Pituitary Foundation says treatment usually means replacing the hormones that are missing, using synthetic forms of the hormones the body normally produces. For most people hormone replacement is life-long. Normally there are no side effects, as the treatment just replaces what the body would produce naturally, but you need ongoing blood tests to make sure the doses are right. The amount you need can vary through life.

If cortisol is low, an illness or injury can tip the body into an adrenal crisis. The Pituitary Foundation calls an adrenal crisis a life-threatening medical emergency and lists causes including sudden vomiting or diarrhoea, severe infection, stopping steroid medicine suddenly or taking it too late, severe injury such as a broken bone, extreme emotional stress and steroid replacement not being given during surgery.

It says to use an emergency 100 mg hydrocortisone injection immediately if you have a kit, then call 999 and say clearly that you are "steroid-dependent" and "having an adrenal crisis", and show your NHS Steroid Emergency Card or medical ID. Following the sick day rules, which involve taking extra steroids by mouth when unwell, can stop a developing problem becoming a full crisis. The NHS says if you take steroids you should carry a steroid emergency card, which tells healthcare professionals you take steroid medicine that should not be stopped suddenly.

For AVP deficiency, the Pituitary Foundation says to seek help if you have missed your desmopressin and have little or no access to fluids. It advises attending your GP without delay for early symptoms such as headache, tiredness and irritability, attending A&E if you also have nausea, low appetite, cramps or muscle spasm, and calling 999 for convulsions or seizures.

Low cortisol can come from the pituitary or from the adrenal glands themselves (Addison's disease). The NHS says Addison's disease is a rare condition where the adrenal glands do not work properly, with symptoms including extreme tiredness, loss of appetite and weight loss, dizziness on standing, muscle weakness and darker areas of skin. Treatment is also steroid replacement, usually for life. The Pituitary Foundation says ACTH deficiency can cause tiredness, low blood pressure and nausea.

The Pituitary Foundation says you should still take your hormone replacement even if you are unwell unless your doctor or specialist advises otherwise, and that if you take hydrocortisone you may need to increase the dose when ill. Missing the occasional dose is unlikely to cause problems, but do not double up the next dose. Growth hormone normally needs to be kept in the fridge, though other pituitary hormone medicines do not. For most people it is fine to drink alcohol within general limits.

It adds that it is common to feel a swing of emotions with a pituitary condition, and that hormone replacements cannot exactly mimic how a healthy pituitary produces hormones. Support is available through its helpline, groups and psychological support.

The Pituitary Foundation says growth hormone is particularly important in children and young people, where a lot of growth happens, and that in children LH and FSH deficiency can cause delayed puberty. Congenital (present from birth) hypopituitarism can be caused by genetic defects in how the pituitary develops.

LH and FSH are important for fertility, and a deficiency can lead to fertility issues. The Pituitary Foundation notes that hypophysitis is most commonly seen during pregnancy and that Sheehan's syndrome follows severe blood loss during childbirth.

On the NHS, your GP can arrange initial blood tests and refer you to an endocrinologist, who coordinates scans, stimulation tests and hormone replacement. The Pituitary Foundation says you will need ongoing blood tests and monitoring once you are on replacement.

Private endocrinology consultations and tests are available for those who want faster access. Hormone replacement and monitoring are usually continued with your NHS endocrine team, and an emergency hydrocortisone kit and steroid emergency card matter whichever route you use.