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Pituitary Gland Flashcards

(49 cards)

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1
Q

Order of hormones affected in hypopituitarism

A 
GH
Gonadotropins (FSH + LH)
TSH
ACTH
Prolactin
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2
Q

Hypopituitarism causes

A

Hypothalamic - Kallman’s, tumour, inflammation, infection (meningitis/TB), ischaemia
Pituitary stalk - trauma, mass lesion, carotid artery aneurysm
Pituitary - Tumour, irradiation, inflammation, autoimmune, infiltration (haemochromatosis, amyloid, metastases), ischaemia

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3
Q

Hypopituitarism tests

A

Test hormones secreted and downstream hormones if necessary e.g. T4 for TSH
IGF-1 for GH axis measurement

Short Synthacten test for adrenal axis
Insulin tolerance test (CI: epilepsy, heart disease, adrenal failure)
Glucagon stimulation test if ITT CI
Arginine + GH test

MRI for hypothalamic/ pituitary lesion

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4
Q

What is insulin tolerance test

A

IV insulin given to induce hypoglycaemia in morning (water only from 22:00 night before), cortisol inc and GH secretion normally triggered
Glucose must fall below 2.2mmol/L
Normally GH>20mU/L and peak cortisol >550nmol/L

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5
Q

Hypopituitarism treatment

A

Hydrocortisone for 2˚ adrenal failure

Thyroxine if hypothyroid

Hypogonadism: Testosterone (enanthate IM 250mg every 3wks) in men and oestrogen in premenopausal women
Gonadotropin therapy needed for fertility

Somatotrophin mimics human GH

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6
Q

Pituitary tumour histological types

A

Chromophobe (70%) - Many non-secretory, half produce prolactin, few produce ACTH/GH; local pressure effect in 30%
Acidophil (15%) - Secrete GH or prolactin; local pressure effect in 10%
Basolphil (15%) - Secrete ACTH; local pressure effect rare

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7
Q

Pituitary local pressure effects

A

Headache

Visual field defect
CNIII, IV, VI palsy

Diabetes insipidus
Hypothalamic disturbances to temp, sleep + appetite

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8
Q

Pituitary tumour tests

A

MRI for intra-/supra-sellar extension

Visual field tests

Screening tests: Prolactin, IGF-1, ACTH, cortisol, TFTs, LH/FSH, testosterone in men, short Synthacten test

Glucose tolerance test if acromegaly suspected
Water deprivation if DI suspected

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9
Q

Pituitary tumour treatment

A

Trans-sphenoidal surgery unless supra-sellar extension then trans-frontal, with pre-op 100mg IV/IM hydrocortisone
Radiotherapy for residual/recurrent adenomas

HRT as needed
Steroids before levothyroxine as thyroxine may cause adrenal crisis
If prolactinoma then dopamine agonist 1st line

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10
Q

What is pituitary apoplexy

A

Rapid pituitary enlargement from bleed into tumour

Can cause mass effects, CV collapse due to acute hypopituitarism

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11
Q

When to suspect pituitary apoplexy

A 
All acute:
GCS drop
Headache
Meningism
Opthalmoplegia
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12
Q

Pituitary apoplexy treatment

A

Hydrocortisone 100mg IV
Fluid balance very well controlled
±cabergoline (dopamine agonist) if prolactinoma
± surgery
Find cause e.g. predisposition to thrombosis from antiphospholipid syndrome

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13
Q

What is a craniopharyngioma

A

Situated between pituitary and 3rd ventricle floor

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14
Q

Craniopharyngioma presentation

A

Over 50% in childhood with growth failure

In adults amenorrhea, dec libido, hypothalamic symptoms, tumour mass effect e.g. visual field

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15
Q

Craniopharyngioma tests

A

CT/MRI (calcification in 50% so may be seen on skull XR)

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16
Q

Craniopharyngioma treatment

A

Surgery ± post-op radiation

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17
Q

Prolactin physiology

A

Secreted by anterior pituitary

Release inhibited by dopamine produced in hypothalamus

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18
Q

Hyperprolactinaemia causes

A

Excess production (e.g. prolactinoma)
Disinhibition through pituitary stalk compression
Dopamine antagonist use (antipsychotics, MDMA, oestrogens, metoclopramide, haloperidol, methyldopa)
Pregnancy/ breastfeeding/ stress
Hypothyroidism (due to inc TRH)
Chronic renal failure (dec excretion)

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19
Q

Hyperprolactinaemia presentation

A 
Menstrual disturbance in women
ED/mass effects in men
Hypogonadism
Osteoporosis
Galactorrhoea
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20
Q

Hyperprolactinaemia tests

Study These Flashcards
A 
Basal prolactin (non-stressful venepuncture between 9-16h)
Pregnancy test
TFT
U+Es
MRI pituitary if other causes ruled out
21
Q

Hyperprolactinaemia management

Study These Flashcards
A 
Refer to endo
Dopamine agonists (bromocriptine/ cabergoline) 1st line
22
Q

Microprolactinoma (<10mm) management

Study These Flashcards
A

Bromocriptine 1.25mg PO titrated up weekly by 1.25mg/d until ~2.5mg/12h
Cabergoline is alternative but safety unknown in pregnancy
Trans-sphenoidal surgery 2nd line due to reoccurence and hormone deficiency risks

23
Q

Macroprolactinoma (>10mm) management

Study These Flashcards
A

Bromocriptine if fertility needed
Surgery followed by bromocriptine ± radiation post op, if visual symptoms or pressure effects unmanageable medically
Monitor closely if medical

24
Q

Hyperprolactinaemia follow up

Study These Flashcards
A

Monitor PRL, check for headaches/visual field loss

Medication can be decreased after 2yrs with monitoring

25
What is acromegaly
Phenotype of increased GH, 99% due to pituitary tumour | GH stimulates bone and soft tissue growth via secretion of IGF-1
26
Acromegaly presentation
``` Acroparasthesia (acro= extremities) Amenorrhoea Inc sweating + snoring Arthralgia + backache Acanthosis nigricans Large jaw, face, nose, hands and feet Proximal weakness + arthropathy Carpal tunnel signs in 50% ```
27
Acromegaly complications
Impaired glucose tolerance (40%), DM (~15%) Vascular - HT, LVH, arrythmias, inc IHD + stroke risk Neoplasia - colon ca risk
28
Acromegaly in pregnancy
Pregnancy may be normal, signs and chemistry may remit
29
Acromegaly tests
Raised glucose, Ca and PO4 If basal GH >0.4mcg/L and/or IGF-1 raised then OGTT, then if OGTT >1mcg/L (glucose normally suppresses GH) then acromegaly confirmed MRI of pituitary fossa Look for hypopituitarism Visual fields/acuity ECG/echo Old photos
30
OGTT in acromegaly testing
Collect samples for GH glucose every 30 mins from 0-150 | False +ves from puberty, pregnancy, hepatic/renal disease, anorexia nervosa and DM
31
Acromegaly treatment
Trans-sphenoidal surgery 1st line Radiotherapy if unsuitable for surgery or as adjuvant Somatostatin analogues (octreotide/lanreotide IM) if surgery fails GH antagonist pegvisomant if SSA not an option, suppresses IGF-1 to normal in 90% but GH levels may rise
32
Acromegaly treatment follow up
``` Yearly: GH, IGF-1 and OGTT Visual fields Vasc assessment BMI Photos ```
33
Acromegaly prognosis
May return to normal, excess mortality mostly vasc complications 16% get diabetes with SSAs, 13% after surgery
34
What is diabetes insipidus
Passing lots of dilute urine (>3L/d) due to impaired water reabsorption in kidney from low ADH secretion (cranial DI) or impaired response to ADH (nephrogenic DI)
35
Diabetes insipidus symptoms
Polyuria/dipsia Dehydration HyperNa symptoms
36
Cranial DI causes
50% idiopathic Congenital - DIDMOAD, ADH defects Tumour - craniopharyngioma, metastases, pituitary Trauma - temporary if distal to pituitary stalk Hypophysitis/ectomy Infiltration - sarcoidosis, histiocytosis Haemorrhage Meningoencephalitis
37
What is DIDMOAD
DI, DM, Optic atrophy, deafness Rare autosomal recessive disorder Also known as Wolfram's syndrome
38
Nephrogenic DI causes
``` Inherited Metabolic - low K, high Ca Drugs - Lithium, demeclocycline Chronic renal disease Post-obstructive uropathy ```
39
Diabetes insipidus tests
Glucose (exclude DM) U+E Serum (285-295mOsmol/kg normally) + urine (2x serum) osmolalities Diagnose with water deprivation tests, primary polydipsia is a differential with hypoNa
40
Cranial DI treatment
``` MRI head, test anterior pituitary function Give desmopressin (ADH analogue) ```
41
Nephrogenic DI treatment
Treat cause Bendroflumethiazide 5mg/24h PO if persists NSAIDs lower urine volume and plasma Na by inhibiting prostaglandin synthase (prostaglandins locally inhibit ADH action)
42
Diabetes insipidus emergency management
Urgent plasma U+Es and serum + urine osmolalities IVI to keep up with urine output, use 0.9% saline initially Lower Na slowly (lower <12mmol/L per day), any faster may cause cerebral oedema + brain injury Desmopressin 2mcg IM (lasts 12-24h) may be used as therapeutic trial
43
8hr water deprivation test when to do it
When established that urine output >3L/d
44
8hr water deprivation test preparation
Free fluids until 7.30, light breakfast at 6.30 if starting at 8.00 No tea, coffee or smoking
45
8hr water deprivation test stage 1
Fluid deprivation start at 8.00 Empty bladder then no drinks, just dry food Weigh hourly, if >3% weight lost or serum osmolality rises>300mOsmol/kg go to stage 2, if less continue stage 1 Collect urine every 2h, measure osmolality and volume Venous osmolality sample every 4h Stop test after 8h if urine osmolality >600 (normal)
46
8hr water deprivation test stage 2
Distinguish between nephrogenic + cranial Give desmopressin 2mcg IM, can drink water now Measure urine osmolality hourly for 4h
47
8hr water deprivation test urine osmolality result interpretations
If normal, urine:plasma osmolality ratio >2 If 1˚ polydipsia, urine concentrates but less than normal e.g. >400-600mOsmol/kg If cranial DI, urine osmolality increase >600 after desmopressin, if ambiguous then extended water deprivation test (from 18.00 night before, no water) If nephrogenic DI, no inc in urine osmolality after desmopressin
48
What is SIADH
Syndrome of inappropriate ADH secretion, even when low plasma osmolality/ large plasma volume
49
SIADH diagnosis
Concentrated urine (Na>20mmol/L and Na osmolality >100mOsmol/kg) with hyponatraemia and low plasma osmolality

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