23rd May 2025

Panhypopituitarism

This is a disorder characterised by the reduced/absent secretion of most or all of the hormones by the pituitary gland. Panhypopituitarism can be due to hypothalamic disease, leading to reduced secretions of releasing hormones, or pituitary disease.

Aetiology

Hypothalamic disease

• Tumour
• Radiation therapy for nasopharyngeal cancer or brain tumours
• Post meningitis 
• Traumatic brain injury
• Stroke

Pituitary disease

• Tumours and lesions, e.g., Pituitary adenoma (most common association with panhypopituitarism)
• Pituitary surgery
• Radiotherapy to the pituitary gland
• Hemochromatosis of pituitary gland
• Immunotherapy side effect, e.g., ipilimumab
• Sheehan syndrome
• Pituitary apoplexy: haemorrhage into infarction or existing adenoma
• Pituitary abscess or infection
• Pituitary stalk interruption syndrome- congenital hypopituitarism
• Empty sella

Clinical Features

• ACTH and cortisol deficiency: postural hypotension, tachycardia, anorexia, reduced libido, hypoglycaemia 
• TSH deficiency: symptoms of hypothyroidism
• Low levels of gonadotropins lead to hypogonadotropic hypogonadism 
• GH deficiency 
• PRL deficiency

Investigations

• U&Es
• Serum and urine osmolality
• Morning cortisol, ACTH, testosterone/oestradiol, FSH, LH
• PRL, IGF-1 levels
• Synthetic ACTH stimulation test: serum cortisol levels taken 30- and 60-mins post injection. Suppression of cortisol (<500 nanomol/L) suggests adrenal insufficiency 
• Can consider tests for Diabetes insipidus and diabetes mellitus
• Consider neuroimaging

Management

• Treat underlying cause
• Deficient hormones are replaced 
• Pituitary apoplexy can lead to acute severe hypopituitarism which is a medical emergency. This is treated with IV hydrocortisone and some cases require emergency surgery.