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Pathology (Guide) > Chemical Pathology - Pituitary > Flashcards

Chemical Pathology - Pituitary Flashcards

(40 cards)

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1
Q

What hormones are produced by the hypothalamus?

A
  • GHRH
  • GnRH
  • TRH
  • Dopamine
  • CRH (corticotrophin-releasing hormone)
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2
Q

Which hormones are produced by the anterior pituitary?

A
  • GH
  • LH
  • FSH
  • TSH
  • Prolactin
  • ACTH (adreno-corticotrophic hormone)
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3
Q

Which hormones produced by the hypothalamus have effects on which pituitary hormones, and what kind of effect?

A
  • GHRH > Stimulates GH
  • GnRF > Stimulates LH + FSH
  • TRH > Stimulates TSH + Prolactin
  • Dopamine > Inhibits Prolactin
  • CRH > Stimulates ACTH
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4
Q

What hormone inhibits GH and where is it produced?

A

Somatostatin (Pancreas)

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5
Q

Where does GH act and what does it produce?

A

Liver
- IGF-1
- IGF-2

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6
Q

Where does TSH act and what does it produce?

A

Thyroid
- T3
- T4

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7
Q

Where does prolactin act and what does it produce?

A

Breast
- Milk

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8
Q

Where does ACTH act and what does it produce?

A

Kidneys
- Cortisol

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9
Q

What is Sheehan’s Syndrome?

A

Pituitary apoplexy (ischaemia of pituitary gland) secondary to PPH

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10
Q

What is the MoA of an antipsychotic?

A
  • Dopamine antagonists
  • Act on D2-receptors
  • Increase prolactin production
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11
Q

What are some contraindications to a combined pituitary test?

A
  • Ischaemic heart disease
  • Epilepsy
  • Untreated hypothyroidism (impairs GH + cortisol response)
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12
Q

What are some side effects to the combined pituitary test?

A
  • Sweating
  • Palpitations
  • LOC
  • Convulsions with hypoglycaemia (rarely)

TRH Injection:
- Metallic taste in mouth
- Flushing
- Nausea

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13
Q

What is the process of the combined pituitary function test?

A
  • Administer LHRH (GnRH), TSH + Insulin
  • Measure pituitary hormone levels at 0, 30, 60, 90 + 120 minutes + glucose
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14
Q

Why is insulin given in the combined pituitary function test?

A

To induce stress to cause a hypoglycaemic state, thus triggering GH + ACTH

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15
Q

What is the procedure for the combined pituitary function test?

A
  1. Fast pt overnight, ensure good IV access, weigh pt
  2. Mix into 5ml syringe (insulin - 0.15IU/kg, 200ug TRH + 100ug LHRH), give IV
  3. Chest bloods every 30 mins + up to 2 hours
  4. Replacement: urgent hydrocortisone, T4, oestrogen + GH
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16
Q

Which hormone levels are measured for up to one hour only and which are measured for up to 2 hours in the combined pituitary function test?

A
  • Glucose, cortisol, GH for 2 hours
  • Thyroxine plus glucose, FHS, TSH, prolactin for 1 hour
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17
Q

What is the outcome of insulin tolerance test?

Study These Flashcards
A
  • Adequate cortisol response (increase >170nmol/L)
  • Adequate GH response (increase >6ug/L)
18
Q

What is the outcome of the thyrotrophin releasing hormone test?

Study These Flashcards
A
  • Normal result = TSH rise >5mU/L
  • Hyperthyroidism = TSH remains suppressed
  • Hypothyroidism = Exaggerated response
  • Not needed to diagnose hyperthyroidism anymore
19
Q

What is the outcome of the gonadotrophin releasing hormone test?

Study These Flashcards
A
  • Normal: peaks at 30-60mins; LH >10U/L, FSH >2U/L
  • Inadequate response = early indication of hypopituitarism
  • Pre-pubertal children should have no response of LH/FSH to LHRH
20
Q

How is a gonadotrophin deficiency diagnosed?

Study These Flashcards
A
  • Basal levels, not dynamic testing
  • Males = low testosterone in absence of raised basal gonadotrophins
  • Females = low oestradiol without elevated basal gonadotrophins + no response to clomiphene
21
Q

What is a microadneoma?

Study These Flashcards
A
  • <10mm
  • Usually benign (prolactinoma)
22
Q

What is a macroadenoma?

Study These Flashcards
A
  • > 10mm
  • Aggressive
  • Usually non-functioning
23
Q

What can happen as a result of a pituitary tumour?

Study These Flashcards
A

Compression of the optic chiasm leading to bitemporal hemianopia

24
Q

What are some generic symptoms of a pituitary tumour?

Study These Flashcards
A
  • Bitemporal hemianopia/superior quadrantanopia
  • Headache
  • Hormone-related symptoms
25
What are some symptoms of acromegaly?
- Soft tissue growth (hands, feet, tongue) - Organomegaly - Sx of HF, HTN, Diabetes - Carpal tunnel
26
How does a non-functioning adenoma lead to increased prolactin levels?
- It can crush the stalk, increasing levels but lowering dopamine inhibition as there's reduced blood flow - Increased prolactin will be relatively small
27
What are the 3 types of prolactinaemia, their classification + causes?
Mild elevation (<1000 miu/L) - Stress - Recent breast examination - Vaginal examination - Hypothyroidism - PCOS Moderate elevation (>1000 miu/L, <5000 miu/L) - Hypothalamic tumour - Non-functioning pituitary tumour compressing hypothalamus - Microprolactinoma - PCOS - Drugs (e.g. phenothiazides, domperidone) Extreme elevation (>5000 miu/L) - Macroprolactinoma
28
What's the most common pituitary tumour, its symptoms and investigation findings?
Prolactinoma Sx: - Amenorrhoea - Galactorrhoea Sx (gynaecomastia, loss of libido, impotence) Ix: - Increased prolactin (>6000) - No increase in GH + cortisol
29
What is the management for a prolactinoma?
1. Replacements (hydrocortisone, T4, oestrogen, GH) + D2 agonists (cabergoline, bromocriptine) 2. Transphenoidal excision (if visual/pressure sx not responding to medical Tx)
30
What is the second most common pituitary tumour, its investigation findings and management?
Non-functioning pituitary adenoma Ix: - Increased prolactin (1000-5000) Mx: - D2 agonists (cabergoline/bromocriptine) - Watch + wait if asymptomatic
31
What is the gold standard investigation for acromegaly + its management?
Ix: - OGTT: Increased GH (even before baseline), Increased prolactin, no increase in cortisol MX: 1. Transphenoidal surgery 2. Pituitary radiotherapy 3. Cabergoline 4. Octreotide (somatostatin analogue) -> can't be stopped once started 5. GH antagonist (pegvisomant)
32
What is the follow-up for a patient with Acromegaly?
Yearly: - GH, IGF-1 +/- OGTT - Visual fields - Vascular assessment - BMI - Photos
33
What are some clinical signs of a patient with acromegaly?
- High glucose - High calcium - High phosphate
34
What hormones are produced in the posterior pituitary, where do they act and what is the result?
ADH (vasopressin) - Blood vessels (vasoconstriction = V1) - Kidneys (water resorption = V2) Oxytocin - Breast (lactation) - Uterus (childbirth)
35
What can cause an excess in ADH?
Lung - Lung paraneoplasias (small cell lung cancer, pneumonia) Brain - TBI - Meningitis - Primary/secondary tumours Iatrogenic - SSRIs - Amitrptylline - Carbamazepine - PPIs Effect - SIADH (euvolaemic hyponatraemia)
36
What can cause ADH failure and how?
- Diabetes insipidus: increased diuresis due to failure of production or insensitivity to ADH, leads to decreased urine osmolality + increased serum osmolality
37
What are the different types of diabetes insipidus and their causes?
Neurogenic (failure of production) - 50% = idiopathic Nephrogenic - Iatrogenic - Lithium - Hypercalcaemic - Renal failure Dipsogenic (failure/damage to hypothalamus + thist drive, hypernatraemia without increased thirst response)
38
What are some symptoms of hypopituitarism?
- Lethargy - Weight gain - Hypotension - Hair loss - Myalgia - Hormone-specific sx
39
What is the management of hypopituitarism?
Hormone-replacement (start with hydrocortisone)
40
What are some causes of hypopituitarism?
- Infection = meningitis (TB) - Inflammation = sarcoidosis - Malignancy = pituitary adenomas (functioning + non-functioning) - Vascular = Sheehan's syndrome, pituitary apoplexy - Iatrogenic = surgery + radiation - Tertiary = Kallman's syndrome

Pathology (Guide) (84 decks)

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