Hypopituitarism

Question 1

Define hypopituitarism

Answer 1

Deficiency of one or more anterior pituitary hormones

Panhypopituitarism is deficiency of all anterior pituitary hormones

Question 2

What are the causes/risk factors of hypopituitarism?

Answer 2

Neoplastic
• Pituitary adenoma
• Craniopharyngioma
• Metastases

Vascular
• Pituitary apoplexy –
haemorrhage/infarction of a
pituitary tumour
• Sheehan’s syndrome –
haemorrhage/infarction following
post-partum haemorrhage

Inflammatory/infiltrative
• TB
• Sarcoidosis
• Haemochromatosis

Infection
• Meningitis
• Encephalitis
• Syphilis
• Abscess

Iatrogenic
• Radiation
• Surgery

Trauma
• Head injury
• Base of skull fracture

Congenital e.g. PROP-1

Question 3

What are the signs and symptoms of hypopituitarism?

Answer 3

LH/FSH 
Children
• Delayed puberty
• Breast atrophy
Females
• Menstrual irregularities
• Dyspareunia
Males
• Gynaecomastia
• Small, soft testes
• Impotence
Both
• Loss of pubic hair
• Reduced libido
• Infertility

GH 
Children
• Short stature
• Failure to thrive
Adults
• Depression
• Fatigue
• Reduced exercise
capacity/muscle strength
• Obesity (increased
abdominal fat)
• Hypertension

TSH 
• Cold intolerance
• Lethargy
• Weight gain
• Constipation
• Hoarse voice
• Depression
• Menorrhagia/menstrual
irregularities
• Facial myxoedema
• Goitre
• Alopecia

ACTH 
• Dizziness
• Anorexia
• Weight loss
• Diarrhoea
• Vomiting
• Abdominal pain
• Lethargy
• Weakness
• Increased pigmentation

Prolactin
• Absence of lactation

Question 4

What investigations are carried out for hypopituitarism?

Answer 4

Basal Tests: 
• 9 am cortisol 
• FSH and LH 
• Testosterone or Oestradiol 
• IGF-1 
• Prolactin 
• TSH 
• fT4 

Basal tests are limited since:

• Cortisol varies diurnally.
• fT4 may be useless in emergency presentations e.g. apoplexy since it has a circulating half-life of 6 days.
• LH and FSH are cyclical in females according to the menstrual cycle.
• GH and ACTH are pulsatile.

Dynamic Tests:
Insulin Tolerance Test:
• Hypoglycaemia < 2.2 mmol/L induces the release of ACTH and GH.
• Give 0.15 U/kg IV insulin.
• In hypopituitarism:
- GH < 20 mU/L
- Cortisol < 550 nmol/L (ACTH is difficult to measure so cortisol measures insread.
• Adrenal Axis:
- Short Synacthen Test
- 250 mg of Synacthen (Synthetic ACTH).
- Measure cortisol 30 mins before and 30 mins after.
- Addison’s is diagnosed if serum cortisol is <550 nmol/L.

• MRI and CT of the brain: to radiologically identify the cause of hypopituitarism.
• Visual field testing: Perimetry to assess the impingement of the optic chiasm.

Question 5

What is the management for hypopituitarism?

Answer 5

• Treat the underlying cause.
• Hormone Replacement:
- ACTH - Hydrocortisone
- Medicalert bracelet and steroid card.
- 2x2 rule in case of illness; IM hydrocortisone before surgery.
- TSH - Levothyroxine (100 mg/ day).
- Taken after hydrocortisone to avoid an Addisonian crisis.
- FSH/LH (F) - Oestrogen ± Progesterone for symptoms and to prevent osteoporosis.
- Gonadotropins for fertility.
- FSH/LH (M) - Testosterone for symptoms and to prevent osteoporosis.
- Gonadotropins for fertility.
- GH - SC Somatotropin (rGH) –1.2 Units/day.
- Children require special monitoring.

Question 6

What are the complications of hypopituitarism?

Answer 6

• Adrenal Crisis
• Hypoglycaemia
• Myxoedema Coma
• Infertility.
• Osteoporosis
• Dwarfism (children)

Complications of the pituitary mass:
• Optic chiasm compression
• Hydrocephalus (third ventricular compression)
• Temporal lobe epilepsy.