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Diabetes and Endocrinology YR3 > Pituitary Gland lecture > Flashcards

Pituitary Gland lecture Flashcards

(49 cards)

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1
Q

Location and relations

A

Base skull
Sella tursica
Attached to hyppthalamus via stalk
Cavernous sinuses either side
Optic chiasm superiorly

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2
Q

Size of pituitary

A

13mm x 9mm 100mg

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3
Q

When does pituitary size change?

A
  • Doubles pregnancy
  • Shrinks elderly
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4
Q

Blood supply to pituitary

A
  • Hypothalamo-hypophyseal portal system
  • Derived from superior and inferior hypophyseal arteries
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5
Q

Venous drainage of pituitary

A
  • Through cavernous sinus into petrosal sinuses and internal jugular veins

Important to know this for venous sampling

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6
Q

What is produced by pituitary gland?

A

8 hormones
6 anterior - FSH, LH, GH, ACTH, TSH, Prolactin
2 posterior - ADH and oxytocin - just stores these, does not produce

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7
Q

What is hypopituitarism

A

Partial or complete deficiency of anterior and or posterior pituitary hormones
May be all hormones, partial or singular
Can be primary or secondary due to hypothalamus pathology

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8
Q

Causes of hypopituitarism

A
  • Pituitary or parapituitary tumours eg meningioma, mets
  • Radiotherapy
  • Infarction - apoplexy, Sheehans
  • Infiltration - sarcoidosis, lymphocytic, haemachromotosis
  • Infection - eg TB/abscess
  • Trauma or SAH
  • Isolated deficiencies - Kallmanns
  • Genetic
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9
Q

Clinical manifestations of hypopituitarism

A
  • GH - short stature if occurs when under 18, reduced exercise capacity
  • FSH/LH - amenorrhoea, anovulation, erectile dysfunction, reduced libido
  • ACTH - hyperkalaemia, hypoadrenal crisis
  • TSH - hypothyroidism
  • PRL - failure lactation
  • ADH - polyuria and polydipsia
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10
Q

Investigations for hypopituitarism

A
  • Basal hormone levels (cortisol done at 9am when highest)
  • Investigate cause - MRI, serum ACE (sarcoid), hCG, ferritin (haemochromatosis) AFP (tumours)
  • Biopsy?
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11
Q

Dynamic testing for growth hormone

A
  • Glucagon
  • Arginine
  • Insulin tolerance test

All try to stimulate glucagon production

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12
Q

Dynamic testing for ACTH

A
  • Short synacthen test
  • Also long - not really used now
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13
Q

Dynamic testing for FSH and LH

A

GnRH administration

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14
Q

Test for ADH deficiency

A
  • Plasma and urine osmolarity
  • Urine Na
  • Fluid deprivation test - see if urine concentrates
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15
Q

Signs of hypersecretion of pituitary hormones

A

Acromegaly
Cushings

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16
Q

Most common brain tumour

A

Adenoma

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17
Q

Classification of pituitary tumours

A
  • Size - macro vs micro
  • Functional vs non-functional
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18
Q

Order of incidence of adenoma types

A
  1. Prolactinoma
  2. Non functioning - mass effect
  3. GH - acromegaly
  4. ACTH adenoma -Cushings disease
  5. TSH adenoma - RARE
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19
Q

Physiological causes of hyperprolactinaemia

A
  • Pregnancy
  • Breastfeeding
  • Exercise
  • Stress
  • Sleep
  • Seizure
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20
Q

Pharmacologcal causes of hyperprolactinaemia

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A
  • Dopamine antagonist - eg haloperidol, risperidone, metoclopramide
  • MAO inhibitors - parkinsons
  • Cimetidine
  • Verapamil
  • Thyrotropin releasing hormone test
21
Q

Pathological causes of hyperprolactinaemia

Study These Flashcards
A
  • Pituitary tumours (prolactinoma)
  • Hypothyroidism
  • CKD
  • PCOS
22
Q

Presentation of prolactinoma

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A
  • Galactorrhoea
  • Amenorrhoea/irregular periods
  • Reduced libido
  • Erectile dysfunction

or mass effect:
* Headache
* CN involvement
* CSF leak
* Hypopituitarism - if compresses

23
Q

Investigations for prolactinoma

Study These Flashcards
A
  • MRI
  • PRL level (less than 2000 suggests micro/stalk effect, more than 4000 means macro)
  • Pituitary function tests
24
Q

What is the hook effect?

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A

Antibodies are bound to some prolactin so some is not read in blood test
If they dilute sample and re do - can trust sample

25
What is macroprolactin? ## Footnote Larg
Large aggregates - prolactin appears larger value than it actually is Use polyethylene glycol to rule out (PEG
26
What is stalk effect?
High levels of prolactin occur due to compression of pituitary stalk causing reduced dopamine release = decreased inhibition of prolactin not actually prolactinoma
27
Aims of treatment for prolactinoma
Micro - restore gonadal function Macro - reduce size and restore function
28
Options of treatment for prolactinoma
* Dopamine agonists eg Cabergoline, Bromocriptine, Pergolide, Oestrogen * Surgery sometimes if compressing chiasm, aggressive * Radiotherapy sometimes too
29
Presentation of acromegaly
* Sweating * Headache * Tiredness * Joint pain * Change in shoe/ring size - enlarged hands and fingers * Frontal bossing - prominent forehead * Enlarged nose * Prognathism - bulging jaw * Macroglossia * Carpal tunnel * Organomegaly
30
Associated co-morbidies with acromegaly
* HTN * DM * OSA * IHD * CHF * Colonic polyps
31
Acromegaly tests
* IGF1 and random GH - not very helpful * **OGTT - should supress GH to less than 0.33** * MRI * Pituitary function test * GNRH - ectopic secretion from carcinoid tumour if no pituitary lesion
32
Treatment for acromegaly cuased by pituitary tumour
* Transphenoidal surgery * Radiotherapy * Medical - somatostatin anologies, dopamine agonists, GH receptor antagonist
33
Causes Cushings **syndrome**
* Pseudocushings - alcoholism, severe depression * Adrenal adenoma/carcinoma/nodular hyperplasia * Exogenous steroids * Ectopic ACTH or CRH
34
Cause of cushings **disease**
Pituitary adenoma secreting ACTH
35
Associated features of Cushings
* HTN * DM * Osteoporosis * Recurrent infections
36
Investigations for Cushings
* 2x 24hr urine cortisol test * Overnight dexamethasone supression test * Salivary cortisol * Midnight cortisol * **Low dose dexamethasone supression test - 100% sensitive almost** and then high dose * ACTH * K+ * CRH
37
Ectopic ACTH vs pituitary ACTH test results
Low K - mostly in ectopic Supression on HDDST - supressed in pituitary (not ectopic) Rise when CRH given - pituitary
38
If unsure if pitutary cushings, another invasive test can do?
Inferior petrosal sampling Compare ACTH to serum If peripheral ratio is more than 2x suggests pituitary cushings Ratio of more than 3 after CRH given is diagnostic
39
Treatment of cushings disease
* Transphenoidal surgery * Radiotherapy * Adrenalectomy (can cause Nelsons syndrome) * Medical - Ketoconazole, Metyrapone
40
What is Nelsons syndrome?
ACTH production increases when cortisol decreases if remove adrenals = enlarge tumour
41
What is diabetes insipidus defined as?
Passage of more than 3L per day of dilute urine Osmolality less than 300mosm/kg
42
Clinical symptoms of DI
* Polyuria * Polydipsia * Nocturia
43
2 types DI
* Cranial or nephrogenic
44
Cause of cranial DI
* Congenitial (DIDMOAD - diabetes insipidus, DM, optic atrophy, deafness) * Acquired due to trauma, infection, infiltration, inflammation, vascular
45
Nephrogenic diabetes cause
* Familial * Acquired - drugs, metabolic, CKD, post obstructive uropathy
46
DI investigations
* More than 3L per day urine * Exclude DM, hypercalcaemia, renal failure * Water deprivation test - if less than 300mosm/kg then diagnostic * Then do desmopressin admistration to see if osmolarity changes by more than 50% - if it does = cranial * MRI brain
47
Treatment of DI
Cranial - desmopressin Nephrogenic - Indomethacin, Thiazide, high dose desmopressin
48
How does Indomethacin work?
NSAID - blocks action of prostaglandins at kidney = less inhibition of ADH
49

Diabetes and Endocrinology YR3 (28 decks)

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