Back to: Endocrinology
Pituitary Gland Conditions
a) Posterior pituitary gland
Diabetes insipidus (DI)
This is a condition which leads to the production of much dilute urine (>3L/day) due to poor water reabsorption.
– It is split into 3 subtypes:
i) Central DI – This is a failure of the pituitary gland to produce ADH
Causes: Idiopathic (50%), congenital defect in ADH gene DIDMOAD + trauma/tumour
ii) Nephrogenic DI – This is an impaired renal response to ADH
Causes: Inherited genes, low K+, high Ca2+, Drugs (e.g. lithium, demeclocycline)
iii) Dipsogenic DI – This is producing large amounts of urine due to drinking too much water
Symptoms – These resemble those of losing water giving hypernatremia
– Polyuria + polydipsia (e.g. kids drinking bathwater) with risk of life-threatening dehydration
– Dilute urine and low specific gravity –> a high urine osmolality (> 700mOsm/kg) excludes DI
Diagnosis – Blood tests show increased Plasma Osmolality, Decreased Urine Osmolality
– Water deprivation test –> this tests ability of the kidney to concentrate urine
–> Patient empties bladder and is then deprived of water for 8 hours
–> Weighed hourly and urine collected every 2h – measure volume and osmolarity
–> After 8h, if urine osmolarity <600mOsmol/kg (dilute), give desmopressin
–> If osmolarity does not increase after 4h, then nephrogenic, otherwise neurogenic
Treatment:
– Central DI –> Desmopressin
– Nephrogenic DI –> Treat the cause + Bendroflumethiazide diuretic – acts as an anti-diuretic
SIADH syndrome
– This is a disease which leads to excessive ADH secretion
Causes:
Often due to ectopic ADH production (e.g. small cell lung carcinoma)
– CNS trauma + Drugs (SSRIs, opiates, TCAs)
Symptoms:
– Hyponatremia (low serum Na+ and low osmolarity) and low volume urine
– This leads to neuronal swelling and cerebral oedema giving rise to seizures, headache
Diagnosis:
Concentrated urine Na+ > 20mM, and >100mOsmol/kg with hyponatraemia (Na+<125mM)
Management:
– Water restriction
– Demeclocycline – an antibiotic which also reduces the sensitivity of the collecting duct to ADH
– ADH receptor antagonists – Vaptan drug family
b) Anterior pituitary gland
Hypopituitarism
– This is decreased secretion of anterior pituitary hormones.
– Most commonly affected hormone is GH –> FSH/LH –> TSH –> ACTH –> Prolactin
Causes – These occur at 3 levels
– Hypothalamus – Kallman’s syndrome, tumour
– Pituitary stalk – Trauma, Carotid artery aneurysm
– Pituitary gland – Adenoma + apoplexy (bleeding of adenoma, haemorrhage of gland)
Sheehan syndrome
During pregnancy, the gland doubles in size but blood supply hardly increases
– Blood loss during parturition gives ischaemia and infarction of pituitary gland
– Patients get fatigued + have poor lactation
Empty Sella syndrome
In this condition, the arachnoid mater and CSF herniate into Sella compressing the pituitary
Kallman Syndrome
This condition occurs due to a failure of development of GnRH neurons derived from olfactory epithelium
– Gives anosmia (lack of smell) + cleft lip + colour blindness
– Low LH/FSH and low sex hormones cause delayed puberty and hypogonadism
– Height is usually normal or above average
Symptoms:
Hypopituitarism gives many symptoms due to the effect on the corresponding hormones.
Tests:
Different tests are carried out to work out which hormones are affected e.g. LH/FSH, IGF-1
Treatment:
Hormone replacement therapy
Pituitary adenoma
This is a benign tumour of the anterior pituitary cells.
– It can be a microadenoma (<1cm) or macro (>1cm)
– Can also be functional (hormone-producing) or non-functional (silent)
– Most common tumour is prolactin secreting –> non-functional –> GH secreting –> ACTH secreting
i) Non-functional tumours – these often present with mass effect due to structural compression
– Can cause bitemporal hemianopia –> compression of the optic chiasm
– Visual disturbances –> pressure on cavernous sinus pressing CN III, IV and VI
– Can cause hypopituitarism –> compression of normal pituitary tissue
– Early morning headaches, worse when lying down
ii) Functional tumours – these present with the features based on the type of hormone produced
– Usually prolactin, GH and ACTH producing – the others are very rare
Tests:
– Pituitary blood profile (GH, prolactin, ACTH, FH, LH and TFTs)
– MRI provides visualization of pituitary gland enlargement
– Formal visual field testing
Management
– If it affects hormones, treat accordingly
– Surgery – transphenoidal hypophysectomy or radiotherapy (residual/recurrent adenomas)
Craniopharyngioma:
– A benign tumour of the epithelial remnants of Rathke’s pouch
– This sits between the pituitary gland and the 3rd ventricle
– It presents as a supratentorial mass in a child or young adult, often leading to compression of the optic chiasm
Symptoms:
(Children) Gives growth failure, and compression of structures
– Bitemporal hemianopia (lower quadrants worse)
(Adults) Amenorrhoea, loss of libido, DI, hyperphagia

Imaging:
– CT/MRI shows calcifications (as if derived from “tooth like tissue”)
Management:
– Surgical removal, but usually recurs after resection
Hyperprolactinemia
This is the most common hormone disturbance on the pituitary
Causes:
– Most often due to a pituitary adenoma increasing production
– Also due to reduced inhibition e.g. dopamine antagonists (Haloperidol, Domperidone)
– Pregnancy and raised oestrogen
– Polycystic Ovary syndrome
– Acromegaly (1/3 of patients)
– Primary hypothyroidism –> as TRH stimulates prolactin release
Symptoms:
As well as direct effects on lactation, raised prolactin inhibits GnRH which decreases testosterone and oestrogen giving secondary effects like osteoporosis.
Females | Males |
Amenorrhea – absence of menstruation | Erectile dysfunction |
Infertility – due to Inhibition of GnRH | Loss of libido |
Galactorrhoea | Galactorrhoea |
Diagnosis:
– MRI visualisation of pituitary gland
Management :
– 1st choice is dopamine agonists to reduce secretion e.g. Bromocriptine/Cabergoline
– 2nd line is surgery
Acromegaly
This is a condition caused by increased secretion of growth hormone from the pituitary
– Most often due to a pituitary adenoma
Symptoms: GH stimulates bone and soft tissue growth through IGF-1
– (Children) – gigantism due to increased bone growth
– (Adults) – enlarged hands, tongue, jaw and feet (increase shoes size)
– Acroparathesia – tingling in the extremities
– Pituitary tumour features (headache + hyperprolactinaemia)
– Excessive sweating and oily skin, due to sweat gland hypertrophy
Complications:
– Growth of visceral organs leads to cardiomyopathy
– Hypertension
– Secondary diabetes mellitus as GH induces gluconeogenesis
– Colorectal cancer
Diagnosis:
– 1st line is to check if Serum IGF-1 level is raised
– Confirmation test is Oral glucose tolerance test –> Normally GH supressed to <2mu/L with glucose
– In acromegaly there is no suppression of GH
– MRI pituitary fossa to visualise tumour
Management:
– 1st line is transphenoidal surgery
– Octreotide – somatostatin analogue, used as adjunct to surgery
– Pegvisomant – GH receptor antagonist, given by subcutaneous injection
– Can use radiotherapy in older patients of if the methods above fail

Sources
Image 1 Craniopharyngioma: Hellerhoff / CC BY (https://creativecommons.org/licenses/by/3.0)
Image 2 Acromegaly: Philippe Chanson and Sylvie Salenave (https://creativecommons.org/licenses/by/2.0