Hypopituitarism Whats the Relevance

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HypopituitarismWhats the Relevance?

• Dr Alison Roberts Dr Anna Murray
• 14th December 2006

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Overview

• Anatomy and physiology of the pituitary gland
• Hypopituitarism
• Causes
• Clinical features
• Management
• Whats the relevance??

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The Pituitary Gland
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Anatomy of the Pituitary Gland

• Enclosed in sella turcica
• Bridged by the diaphragma sellae
• Sphenoidal air sinuses below
• Optic chiasm above
• Cavernous sinuses lateral to pituitary fossa
  (contain 3rd, 4th and 6th cranial nerves and
  internal carotid arteries)

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Anatomy of the Pituitary Gland

• Anterior and posterior lobes
• Intermediate lobe rudimentary in humans
• Connected to the hypothalamus by the infundibular
  stalk
• Portal vessels carry blood from hypothalamus to
  the anterior lobe and nerve fibres to the
  posterior lobe

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Pituitary Hormones

• Anterior pituitary hormone secretion stimulated
  or inhibited by hypothalamic hormones
• Feedback control by hormones produced by the
  target glands
• Posterior pituitary hormones synthesised in the
  hypothalamus and transported down nerve axons to
  the pituitary

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Pituitary Hormone Functions
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Pituitary Hormone Functions
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Causes of Hypopituitarism

• Pituitary tumour
• Sheehans syndrome
• Craniopharyngioma
• Pituitary granulomatous lesion (TB, sarcoidosis,
  syphillis)
• Iatrogenic
• Hypophysectomy
• XRT to sella or nasopharynx
• Head injury
• Idiopathic

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Impairment of Hormones

• Gonadotrophin
• Growth Hormone
• TSH
• ACTH
• ADH

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Clinical Features

• Male to female ratio 12
• Pallor
• Reduced pubic, facial, axillary and body hair
• Atrophy of breasts and genitalia
• May have signs of hypothyroidism
• Adrenal insufficiency
• Diabetes insipidus

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Clinical Features

• Factors leading to coma
• Hypoglycaemia
• Sodium depletion
• Water intoxication
• Cerebral anoxia
• Hypothyroidism
• Hypothermia
• Pressure on midbrain or hypothalamus

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Management

• Replacement of the appropriate hormones

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So What is the Relevance?
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Radiotherapy Induced Hypopituitarism

• Radiation to the hypothalamic-pituitary axis
• Pituitary tumours
• Nasopharyngeal carcinomas
• Tumours of the skull base
• Whole brain radiotherapy does not cause
  hypopituitarism

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Metastatic Tumours

• Breast and lung cancer most common tumours
  metastasizing to the pituitary
• Usually multiple metastatic sites
• May be first manifestation of occult primary
  tumour
• Antemortem diagnosis difficult majority are
  clinically silent
• 5 of patients with known malignancy at
  post-mortem

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Metastatic Tumours

• Symptoms reported in 2.5-18.2 of cases
• Usually occur in end-stage cancer patients with
  no time to become evident
• Other symptoms of cancer may mask hypopituitarism
• Most cases diagnosed at PM or following
  palliative hypophysectomy in metastatic breast
  cancer

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Metastatic Tumours

• Predilection for the posterior lobe due to blood
  supply of the pituitary and larger area of
  contact with the dura
• Deposits in the anterior lobe usually result of
  spread from the posterior lobe
• Most common symptom is diabetes insipidus
• Occasionally present with a hyperfunctional
  syndrome

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Metastatic Tumours

• Visual field impairment
• Cranial nerve palsies
• Cognitive deficit or psychiatric symptoms if
  frontal lobe involved
• Rapid increase of a sellar tumour with aggressive
  infiltration of adjacent tissues should raise
  suspicion of a pituitary metastasis

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Treatment and Prognosis

• Total resection unlikely but surgery may
  alleviate symptoms
• XRT and/or chemotherapy
• Hormone replacement
• Prognosis poor mainly due to aggressiveness of
  the primary tumour
• Mean survival in clinical series 6-7 months

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Conclusion

• Hypopituitarism is uncommon
• Rarely caused by pituitary metastases so we could
  potentially encounter it in such a situation
• More likely that we will treat someone with
  cancer who also happens to have hypopituitarism