Synopsis
Identify loss of individual or multiple pituitary axes, protect cortisol before other replacement, and provide lifelong cause-specific hormone, fertility, water-balance and emergency follow-up.
- Hypopituitarism may follow pituitary or hypothalamic tumour, surgery, radiotherapy, apoplexy, head injury, subarachnoid haemorrhage, infiltrative disease, infection, genetic disease or immune checkpoint therapy.
- Hormone loss can be isolated, sequential or complete; ACTH deficiency is the immediately dangerous component and may present with normal potassium because aldosterone remains renin-angiotensin regulated.
- In central hypothyroidism, free T4 is low with TSH that is low, normal or only mildly raised; TSH cannot be used as the levothyroxine dose target.
- Secure cortisol secretion or give glucocorticoid cover before thyroid replacement, because increasing thyroid hormone in an ACTH-deficient patient can precipitate adrenal crisis.
- Low gonadotrophins with low sex hormone causes amenorrhoea, infertility, low libido, erectile dysfunction, hot flushes and bone loss; replacement and fertility induction have different goals and regimens.
- Random growth hormone is not diagnostic because secretion is pulsatile; adults usually require appropriate dynamic testing after other pituitary deficits have been replaced.
- Posterior pituitary disease causes arginine vasopressin deficiency with polyuria and thirst; desmopressin can cause fatal hyponatraemia if fluid intake and sodium are not managed.
- Patients with ACTH deficiency need daily adherence, sick-day dosing, an NHS Steroid Emergency Card, emergency injection education and procedure-specific cover.
Key red flags
Shock, recurrent vomiting, severe weakness, altered consciousness or hypoglycaemia in a patient with pituitary disease demands immediate hydrocortisone and resuscitation for possible adrenal crisis.
Sudden headache with visual or ocular-motor change requires the pituitary apoplexy pathway rather than routine hormone adjustment.
Rapid visual decline or new bitemporal field loss suggests compressive sellar progression and needs urgent MRI and specialist assessment.
Polyuria with hypernatraemia, inability to access water or impaired consciousness is a water-balance emergency requiring monitored fluid and endocrine care.
Severe hyponatraemia, confusion or seizure while taking desmopressin suggests water intoxication and needs immediate drug, fluid and sodium management.
Investigation priorities
Screen the ACTH-cortisol axis before elective replacement or dynamic testing.
Management branches
Pituitary disease or treatment creates symptoms compatible with partial or complete hormone loss.
- Identify urgent cortisol, visual, neurological and sodium threats before arranging non-urgent dynamic investigations.
- Measure paired target and trophic hormones, document exogenous steroids and hormone therapies, and obtain dedicated pituitary imaging where cause is unknown.
- Classify each axis as intact, deficient, uncertain or confounded rather than applying a single diagnosis of panhypopituitarism.
- Agree replacement sequence, definitive tumour treatment and a timed reassessment plan through the pituitary multidisciplinary service.