Hypopituitarism

Anterior pituitary gland (adenohypophysis):

Responsible for the synthesis and secretion of the following hormones:

• Growth hormone (GH, somatotrophin)
• Prolactin
• TSH (thyroid stimulating hormone, thyrotrophin)
• ACTH (adrenocorticotrophic hormone, corticotrophin)
• LH (luteinizing hormone)
• FSH (follicle stimulating hormone)

Posterior pituitary gland (neurohypophysis):

Responsible for the secretion of the following hormones:

• VP (vasopressin, ADH, antidiuretic hormone)
• Oxytocin

Pathophysiology:

• Deficiency of hypothalamic releasing hormones or of pituitary trophic hormones are either selective or multiple
• Multiple deficiencies usually result from tumour growth or other destructive lesions
• With the latter, there is generally a progressive loss of anterior pituitary function (GH and gonadotrophins, LH before FSH, are usually first affected
• Rather than prolactin deficiency, hyperprolactinaemia occurs relatively early because of tonic inhibitory control by dopamine
• TSH and ACTH are usually last to be affected
• Panhypopituitarism refers to a deficiency of all anterior pituitary hormones. It is most commonly caused by:
• Pituitary tumours
• Surgery
• Radiotherapy

Causes:

Congenital:

• Isolated deficiency of pituitary hormones (Kallmann’s syndrome)

Infective:

• Basal meningitis
• Encephalitis
• Syphilis

Vascular:

• Pituitary apoplexy
• Sheehan’s syndrome (post-partum necrosis)
• Carotid artery aneurysms

Immunological:

• Pituitary antibodies

Neoplastic:

• Pituitary or hypothalamic tumours
• Craniopharyngioma
• Meningiomas
• Gliomas
• Metastases (especially from breast)
• Lymphoma

Traumatic:

• Skull fracture through base
• Surgery (especially transfrontal)

Infiltrations:

• Sarcoidosis
• Hereditary haemochromatosis

Others:

• Radiation damage
• Fibrosis
• Chemotherapy

‘Functional’:

• Anorexia nervosa
• Starvation
• Emotional deprivation

Clinical features, investigations and treatment:

All vary depending on the hormones affected – see relevant notes