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MEH > Pituitary Disorders incl DI > Flashcards

Pituitary Disorders incl DI Flashcards

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1
Q

What is osmolarity?

A

concetration of a solution expressed as number of solute particles per litre
mOsm/kg
think of the amount of liquid

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2
Q

What is osmolarity?

A

concentration of solution expressed as number of solute per kg of solvent
mOsm/kg
think of amount of stuff dissolved

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3
Q

Clinical presentation of pituitary tumours

A
  • pressure on surrounding structures > visual loss, headache, vomiting, nausea
  • abnormality on pituitary function > hyper/hypo secretion
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4
Q

Reason for visual field loss in pituitary tumours

A

Upwards (superior) growth of pituitary tumour
Pressure on the optic chiasm
bitemporal haemianopia

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5
Q

Consequences of sideways (lateral) growth of pituitary tumour

A

Pain
Double vision

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6
Q

Consequences of upwards (superior) growth of pituitary tumour

A

Visual field loss due to pressure on optic chiasm causing bitemporal hemianopia

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7
Q

what is hypopituitarism?
What is it commonly caused by?

A
  • diminished hormone secretion by the anterior pituitary gland (+ADH)
  • pituitary adenoma
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8
Q

Changes in hormone levels in hypopituitarism

A

all go down apart from prolactin increase
due to disinhibition hyperprolactinaemia

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9
Q

What is the best imaging modality for pituitary gland?

A

MRI head

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10
Q

what does Growth hormone deficiency cause?

A

Short stature in children - pituitary dwarfism
Reduced quality of life in adults

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11
Q

what does Gonadotropin (LH + FSH) deficiency cause?

A
  • delayed puberty
  • loss of secondary sexual characteristics in adults
  • early sign: loss of periods
  • lack of libido
  • infertility + impotence
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12
Q

what does TSH deficiency cause?
Symptoms

A

Hypothyoidism
- low thyroid hormones
- weight gain
- fatigue
- bradycardia
- non elevated TSH
- low T4
- intolerance to cold

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13
Q

what does ACTH deficiency cause?

A

ACTH controls cortisol
- low cortisol
- tired
- dizziness
- hypotension
- hyponatraemia
Can be life threatening

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14
Q

What are the common hormones in excess in abnormalities in pituitary function?

A
  • prolactin
  • GH
  • ACTH
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15
Q

What are the rare hormones in excess in abnormalities in pituitary function?

A
  • TSH
  • LH/FSH
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16
Q

What do you do if you think a hormone is too low?

A

Stimulation test

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17
Q

What do you do if you think a hormone is in excess?

A

Suppression test

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18
Q

Adrenal axis tests

A

Deficiency- synacthen test, insulin stress test
Excess- dexamethasone suppression test

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19
Q

Who should an insulin stress test not be done on and why?

A

patients with ischaemic heart disease or epilepsy
risk of triggering coronary ischaemia or seizures respectively

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20
Q

GH axis tests

A

Deficiency: insulin stress test
Excess: glucose tolerance test

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21
Q

2 types of prolactin-secreting pituitary tumours

A

Large tumour = macro-adenoma (>1 cm)
Small tumour = micro-adenoma (<1 cm) (more common)

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22
Q

Outline micro-prolactinomas incl. symptoms

A
  • most common pituitary tumours
  • F>M
  • <1cm
  • presentation of menstrual disturbances (or hypogonadism in men), galactorrhoea, infertility
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23
Q

How can PCOS and micro-prolactinomas be distinguished

A

PCOS has:
- presence of androgenic symptoms
- less elevated prolactin levels
- absence of pituitary lesion on MRI

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24
Q

what is the most common cause of hyperprolactinaemia?
+ physiological causes

A

prolactinoma - pituitary adenoma that secretes prolactin

pregnancy
stress
Suckling
exercise
drugs

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25
Causes of hyperprolactinaemia
- medications *e.g. anti-emetics, antipsychotics* - PCOS - prolactinoma - non functioning adenoma causing compression of pituitary stalk - pregnancy - profound hypothyroidism (rare)
26
how does hypogonadism arise from hyperprolactinaemia?
- increased plasma prolactin - higher levels of dopamine for negative feedback - dopamine inhibits GnRH secretion - inhibition of FSH + LH secretion
27
How are prolactinomas treated?
- dopamine agonists *e.g. cabergoline, bromocriptine* - not operation Ensure patient isn’t pregnant
28
What does dopamine inhibit?
Prolactin GnRH > FSH + LH
29
What does prolactin inhibit?
Luteinising hormone Ovulation and secretion of sex hormones
30
Symptoms on hyperprolactinaemia in women
- **menstrual disturbance** - **fertility problems** - hypogondasim - **galactorrhea** - excessive or inappropriate milk production - **gynecomastia** - hard breast tissue
31
Symptoms of hyperprolactinaemia in men
- present later than women - no periods - larger tumours - low testosterone - hypogonadism - ED - may have mass symptoms e.g. visual loss
32
What is Acromegaly What is it due to?
- Large extremities - Large hands and feet - due to GH secreting pituitary adenoma in adults
33
Clinical features of acromegaly
- increased size of feet + hands - coarser facial features over time - chin protrusion - widely spaced teeth - frontal bossing of forehead - enlargement of tongue + soft palate > snoring + sleep apnoea - excessive sweating + oily skin - headaches, hypertension, DM
34
Complications of untreated acromegaly
- premature cardiovascular death - irreversible changes in appearance - increased risk of thyroid + bowel cancer - hypertension - diabetes - cardiomyopathy
35
Investigations of acromegaly
- oral glucose tolerance test - serum IGF-1 levels - MRI to identify pituitary adenoma
36
Biochemical test to confirm acromegaly
- oral glucose tolerance test resulting in failure to suppress GH - elevated IGF-1
37
Treatment of acromegaly
- trans-sphenoidal removal of tumour - *dopamine receptor agonists* *e.g. cabergoline* - *somatostatin analogues* *e.g. octreotide* - Radiation therapy
38
Drug treatment of acromegaly
- dopamine agonists *e.g. cabergoline* - somatostatin analogues *e.g. octerotide*
39
outline monitoring of disease activity in acromegaly
- oral glucose tolerance test post-surgery to indicate persistent disease - periodic colonoscopy due to increased colon cancer risk - assessment for sleep apnoea, diabetes + cardiovascular disease due to increased risk
40
what causes Cushing’s disease
ACTH-secreting pituitary tumour
41
Changes in appearance in Cushing’s disease
- round pink face - round abdomen - thin skin - bruises easily - striae/stretch marks - osteoporosis- thin bones - high BP -diabetes - skinny arms and legs
42
What is primary polydipsia?
When patient has normally functioning ADH but drinks excessive amounts of water > polyuria
43
Types of diabetes insipidus
- **Cranial DI**: *ADH deficiency* - in pituitary disease - **nephrogenic DI**: *ADH resistance* in kidney - metabolic + electrolyte disturbance, renal disease or nephrotoxic drugs
44
Causes of cranial diabetes insipidus
- idiopathic - brain surgery/tumour/infection - damage to pituitary/hypothalamus gland
45
Causes of nephrogenic diabetes insipidus
- nephrotoxic medications *e.g. lithium* - hypercalcaemia - hypokalaemia - PCOS - renal disease - haemochromatosis
46
Presentation of diabetes insipidus
polyuria polydipsia dehydration postural hypotension
47
Investigations + findings of diabetes insipidus
- high serum osmolality - low urine osmolality - high urine volume (>3L per 24 hours) - water deprivation test - U&Es
48
What is the plasma osmolality + urine osmolality in diabetes insipidus? why?
- **high plasma osmolality**: ADH deficiency or resistance > more water lost in urine > more water lost than solutes > plasma more concentrate > more solute per kg of water - **low urine osmolality**: more water lost in urine > more dilute urine > less solute per kg of water
49
Diagnosis of diabetes insipidus
water deprivation test
50
Outline the water deprivation test / desmopressin stimulation test
- patient avoids all fluids for 8 hours before test - urine osmolality is measured - if low, desmopressin (synthetic ADH) is given - urine osmolality measured over 24 hours after
51
Outline the results of water deprivation test in: - primary polydipsia - cranial DI - nephrogenic DI
- **primary polydipsia**: high UO after deprivation - **Cranial DI**: low UO after deprivation + high UO after desmopressin - **nephrogenic DI**: low UO after depravation+ desmopressin
52
Consequences of untreated diabetes inspidus
- dehydration - hypernatraemia - reduced consciousness - coma - death
53
Management of cranial diabetes insipdius
- ***desmopressin*** (synthetic ADH) - monitor serum sodium - risk of hyponatraemia - investigate for pituitary disease
54
Management of nephrogenic diabetes insipidus
- treat underlying cause - stop damaging drugs - drink according to thirst - thiazide diuretics - NSAIDs - low salt - low protein diet
55
What organ produces IGFs?
Liver
56
outline the clinical approach of the investigation of a suspected pituitary tumour
- **endocrine function assessment**: hormone levels + biopsy of tumour w antibiotics for hormone - **visual field defects assessment** - **MRI scan**
57
what is hypopituitarism often due to?
pituitary adenoma > progressive loss of anterior pituitary function
58
what is panhypopoituitarism?
deficiency in all anterior pituitary hormones
59
What is hyperpituitarism? What is it commonly caused by?
- Excess pituitary hormone production (prolactin, GH + ACTH) - due to functional hypersecreting pituitary adenoma
60
What is a pituitary apoplexy
Bleeding into or impaired blood supply of the pituitary gland
61
Symptoms of pituitary apoplexy
Sudden onset headache Double vision Cardinal nerve palsy Visual field loss Hypopituitarism
62
What is the most common causes of pituitary disorders? Describe this
**Pituitary adenoma** - benign tumour - often non functioning (do not produce any hormones) - have negative effect due to pressure exerted
63
What hormones are most commonly affected by Hypopituitarism?
- ACTH - ADH - TSH - Growth hormone - Gonadotrophin (LH/FSH)
64
What hormones are most commonly affected in hyperpituitarism?
Prolactin Growth hormone ACTH
65
What can a GH excess cause in childhood vs adulthood?
Childhood - **gigantism** Adulthood - **acromegaly**
66
Why can growth hormones excess cause diabetes mellitus?
**GH antagonises insulin**

MEH (23 decks)

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