Pituitary gland abnormalities (week 4) Flashcards
What are the hormones secreted by anterior pituitary gland
Prolactin
ACTH
TSH
GH
LH and FSH
What are the hormones secreted by posterior pituitary gland
Oxytocin
ADH
Function of prolactin
stimulate breast milk production, breast tissue growth
Function of ADH (anti diuretic hormone)
Controls how much water is excreted into urine
Function of GH
growth and development
Function of ACTH
stimulates adrenal cortex to produce cortisol
Function of oxytocin
Stimulates uterine contraction during labour
Promotes breastfeeding
Pituitary pathologies can be
Hyperfunction / hypofunction
Hyperfunction of the the pituitary is caused by
Secreting adenomas
Adenomas can be (function, size)
Secreting / non-secreting
Micro/Macro
How may macro adenomas cause hypopituitarism
Due to large infarction of the pituitary gland tissue
Symptoms of non-secreting adenomas
Headaches
Impaired visual field
Investigation for non-secreting adenomas
MRI
Hormone tests to exclude other causes
Management for non-secreting adenomas
Surgery
Radiotherapy
Types of secreting adenomas
Prolactinoma
GH secreting adenoma
ACTH secreting adenoma
TSH secreting adenoma (very rare)
What does TSH secreting adenoma cause
Secondary hyperthyroidism (very rare)
Most common secreting pituitary adenomas
Prolactinoma
Symptoms of hyperprolactinaemia due to prolactinoma
females - oligomenorrhea/amenorrhea, infertility, vaginal dryness, galactorrhea
Males- erectile dysfunciton, gynaecomastia, reduced facial hair
Both- headaches, low sex drive, impaired visual fields
Investigations for prolactinoma
Serum prolactin level
Serum level of other hormones
MRI
Results of investigations for prolactinoma
Raised prolactin
Decreased level of other hormones
Lesions / tumour seen on MRI
Management for small prolactinoma
Dopamine agonists
Hormone therapy - oestrogen
Management for larger prolactinoma
Surgery
What dopamine agonists are used for prolactinoma
cabergoline
Side effects of cabergoline (dopamine agonists)
Nausea / vomiting
low mood
obsessive compulsive behaviour
If a patient with small prolactinoma has been taking dopamine agonists for over a year and has not experienced any symptoms, what should you do? - continue the treatment ?
Stop dopamine agonist because hyperprolactinaemia is likely to resolve
Start again if hyperprolactinaemia persist
Hormone replacement therapy is used in prolactinoma if
fertility and galactorrhea are not issues
Types of causes of hyperprolactinaemia
Physiological
Pathological - prolactinoma
Physiological causes of hyperprolactinaemia
Pregnancy
Breastfeeding
Anxiety
Use of dopamine antagonists
Use of anti-psychotics
Examples of dopamine antagonists
Risperidone
Metoclopramide
What is SIADH (syndrome of inappropriate ADH production)
Excessive ADH production due to pathology in posterior pituitary / ectopic ADH
What damage to the brain can cause SIADH
subarachnoid haemorrhage (bleeding on the surface of the brain)
What are the non-pituitary cause of SIADH
Small cell lung cancer
Lymphoma
Infections
Pneumothorax
Cystic fibrosis
Chemotherapy
What is a common PMH in patients with SIADH
Lung cancer (small cell lung cancer)
Symptoms of SIADH is caused by
hyponatraemia
Symptoms of SIADH
Muscle cramping
Nausea
Vomiting
Confusion / reduced GCS level
Seizures
Investigations for SIADH
Urea and electrolytes
Plasma osmolarity
Urine osmolarity
Urine sodium
MRI
Results for investigations for SIADH
U&E - hyponatraemia
Plasma osmolarity - reduced
Urine osmolarity - raised
Urine sodium - raised
Why is there hyponatraemia in SIADH
Because excessive ADH causes excessive retaining of water = blood becomes very diluted = hyponatraemia and reduced plasma osmolarity
Why is urine osmolarity raised in SIADH
Because water is retained in the body and not passed out into the urine so urine becomes very concentrated
Management of mild SIADH
Fluid restriction
Treat the underlying cause via surgery
Management of moderate-severe SIADH
Rapid correction of hyponatraemia by
1. Hypertonic saline
2. Loop diuretics
3. Democlocycline (tetracycline)
4. Vasopressin antagonist
Mechanism of democlocycline
Blocks ADH and induces partial nephrogenic diabetes insipidus
What is panhypopituitarism
reduction in all hormones produced by the pituitary gland
What causes panhypopituitarism
Surgery / radiotherapy
Haemorrhage, infarction - Sheehan’s
TB meningitis
Sarcoidosis
What is Sheehan’s syndrome
Maternal hypopituitarism due to excessive bleeding during labour
Symptoms of panhypopituitarism
hypothyroidism - MOMS SO TIRED
prolactin deficiency - oligo/amenorrhea, infertility, sexual dysfunction, breast atrophy, hypogonadism
Adrenal deficiency
GH deficiency - obesity, muscle weakness, reduced exercise tolerance
ADH deficiency (diabetes insipidus)
Types of ADH deficiency
Cranial diabetes insipidus
Nephrogenic diabetes insipidus
ADH deficiency (diabetes insipidus) can be due to
- ADH production deficiency = cranial diabetes insipidus
- Kidneys become ADH resistant i.e. they stop responding to ADH = nephrogenic diabetes insipidus
What chemical can cause nephrogenic diabetes insipidus
Lithium toxicity
Symptoms of ADH deficiency
Polyuria
Polydipsia
Thirst
Lethargy
Confusion/ reduced GCS
Seizures
Investigations for ADH deficiency
U&E
Plasma osmolarity
24 hour urine collection - urine sodium and urine osmolarity
Fluid deprivation test
Results of investigations that suggests ADH
U&E - hypernatraemia
Plasma osmolarity - raised
Urine sodium - low
Urine osmolarity - low
Fluid deprivation test - urine becomes concentrated
Describe the fluid deprivation test
Deprive patients from fluid for a certain amount of time
Then administer desmopressin (synthetic ADH)
If urine becomes concentrated = ADH deficiency
How does ADH deficiency cause hypernatraemia and raised plasma osmolarity
Because more water is passed out into the urine making the blood very concentrated and urine very diluted
Treatment for ADH deficiency
Desmopressin
What is phaeochromocytoma
Catecholamine-releasing tumour arising from the adrenal gland
Where is phaeochromocytomas derived from
Chromaffin cells of adrenal medulla
Are phaeochromocytomas malignant
Only 10% are and metastasise to elsewhere
Apart from the adrenal medulla, do catecholamine releasing tumours appear at other sites
Yes but rare, sympathetic neurone
= paraganglioma
Most common association with phaeochromocytoma
Persistent hypertension
Phaeochromocytomas mainly occur in which age group
30-50 years old
Symptoms of phaechromocytoma
Hypertension (can be episodic)
Fatigue
Sweating
Palpitations
Tremor
Weight loss
Anxiety
Postural hypotension
Hypertensive retinopathy
Symptoms of phaeochromocytomas can be exacerbated by
Stress
Exercise
Surgery
Opiates
Beta Blockers
Investigations for phaeochromocytoma
- Plasma metanephrine
- Urine metanephrine
- Adrenal imaging
- CT chest, abdomen, pelvis
What is metanephrine
Substance released when catecholamines are broken down
Management for phaeochromocytomas
- Alpha blockade first then Beta blockade
- surgery
Which one should be used first, alpha blockade or beta blockade
alpha blockade
Why should we use alpha and beta blockades before surgery for phaeochromocytoma
To increase blood volume and prevent hypertensive crisis
Example of an alpha blockade
Phenoxybenzamine
What is MEN syndrome
Multiple endocrine neoplasia; the formation of multiple hormone secreting tumours at multiple endocrine sites
What causes MEN syndrome
Mutation in tumour suppression gene
Inheritance pattern of MEN syndrome
Autosomal dominant
Types of MEN syndrome
MEN 1
MEN 2a
MEN 2b
Conditions associated with MEN 1 (the P syndrome)
- Pituitary adenoma (esp prolactinoma)
- Parathyroid gland hyperplasia
- Pancreatic tumours
What are the pancreatic tumours that can present in MEN 1
Insulinoma
Gastrinoma
What type of pituitary adenoma is the most common in MEN 1
Prolactinoma (acromegaly second)
Describe the hormone level changes due to parathyroid gland hyperplasia
Serum Ca2+ elevated
Serum PTH elevated
Urine calcium:creatinine elevated
What symptoms are caused by hypercalcaemia (Stones, Bones, Groans, Moans)
Renal calculi
Abdominal pain, nausea, vomiting
Psychosis
Lethargy
Depression
Painful bones
Osteoporosis
Fragility fractures
Hypertension
Investigations for MEN 1
Genetic test
Hormone level (Ca2+, PTH, prolactin, urine Ca:creatinine)
Screen asymptomatic family members
What are the conditions associated to MEN 2a
- Parathyroid hyperplasia
- Medullary thyroid carcinoma
- Phaeochromocytomas
What are the conditions associated to MEN 2b
- Marfanoid
- Neuroma
- Medullary thyroid carcinoma
- Phaeochromocytoma
Investigations for MEN 2
Genetic test
For phaeochromocytoma -plasma and urine metanephrine
For medullary thyroid carcinoma - calcitonin level and fine needle aspiration of the tumour
For parathyroid hyperplasia
Management for MEN syndromes
Surgery