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endocrine pathology + medicine > endocrine- pituitary > Flashcards

endocrine- pituitary Flashcards

1
Q

List pure and mixed endocrine organs

A 
Pure endocrine organs
•Pituitary
•Thyroid
•Parathyroid
•Adrenal – Cortex & Medulla

Endocrine components in mixed organs
•Pancreas
•Ovary
•Testis

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2
Q

Explain the regulatory control mechanisms of the endocrine system

A

Endocrine glands under regulation by stimulatory and inhibitory signals facilitated by

  • trophic releasing hormones
  • trophic hormones
  • feed back inhibition
  • release inhibiting hormone
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3
Q

Outline the diseases of the endocrine organ

A

Hyperfunction – excessive secretion of hormones
•Hypofunction – decreased secretion of hormones
•Enlargement / mass effect
•Functional
•Non functional

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4
Q

Explain causes of hypofunction and hyperfunction

A

HYPERFUNCTION •Hyperplasia or neoplasia of hormone secreting cells
•Secondary hyperfunction – increased stimulation / decreased feedback inhibition
•Ectopic hormone production

HYPOFUNCTION
Primary hypofunction
•Congenital absence
•Hypoplasia
•Destruction of the gland
Secondary hypofunction
•Absence of trophic hormones
Pseudohypofunction
•Target organ receptors not functioning
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5
Q

What is the weight and measurement of the pituitary gland?

A

500 mg , 10-15mm

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6
Q

What is the structure of the pituitary lobe?

A

Anterior lobe(adenohypophysis)- derived from Rathke’s pouch

Post lobe(neurohypophysis) - derived from 3rd ventricle

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7
Q

Where is the pituitary gland located?

A

Sella turcica between the hypothalmus and pineal gland

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8
Q

What are the 3 cell types of anterior pit?

A

acidophils, basophils, chromophobes

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9
Q

How is the anterior pit controlled?

A

By positive/negative stimulus from hypothalamus
Hypothalamus secretes the following hormones to stimulate release of trophic hormones from the anterior pit.

Corticotropin releasing hormone: adrenocorticotropin hormone

Thyrotropin releasing hormone: thyroid stimulating hormone

Growth hormone releasing: Growth hormone

Gonadotropin releasing hormone : FSH, LH

Somatostatin- inhibitory to growth hormone

Dopamine- inhibitory to prolactin

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10
Q

What are the causes of hyperpituitarism ?

A

functioning adenoma
rarely a carcinoma; must show mets for diagnosis
very rarely other pathology like hyperplasia

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11
Q

Describe pituitary adenomas

A

10% primary intracranial neoplasms
most common 40-60 yrs
rarely apart of MEN type 1

Two types
Functional (hormone secreting neoplasm)
Non functional adenoma (30%)

further classification
microadenoma <1cm
macroadenoma >1cm

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12
Q

What is the most common functional pituitary adenoma?

A 
Prolactinoma - 30% 
Somatotrophic adenoma- 15% 
Adrenocorticotrophic adenoma- 10% 
Mixed- 5% 
Gonadotrophic adenoma-5% 
Thyrotropic - rare
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13
Q

What are the symtoms aw pituitary adenomas?

A 
1.Hormone overproduction
•Prolactin
•GH
•ACTH
•TSH
•FSH/LH
2.Space effect
•Incidental on imaging
•Optical chiasm pressure – bitemporal hemianopia
•Hormone deficiency
•Rarely symptoms of increased ICP
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14
Q

What is a prolactinoma and a/w symtoms

A

a/w excess release of prolactin
Besides pressure effects, in males - asymptomatic, libido ,infertility
females: amenorrhea, galatorrhea , sterility

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15
Q

What besides a prolatinoma causes increase in prolactin levels?

A

pregnancy/lactation

stalk compression

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16
Q

How do you diagnose a prolactinoma?

A

Assess pituitary function
by checking thyroid function - free T4, TSH (TSH dependent prolactin release can occur as TRH has a +ve effect on prolactin release)
gonadal axis function - testosterone, oestrogen, FSH, LH (prolactin can inhibit GRH)
IGF-1 - if low deficiency in GH
Insulin tolerance test- assess cortisol and GH response to hypoglycaemia
serum prolactin
short synacten test- IM synthetic ACTH which assesses cortisol at baseline and 30 mins

Do MRI

17
Q

How are prolactinomas treated?

A

Surgery

dopamine agonist ; bromocriptine

18
Q

What are features of growth hormone ademona/somatrotropic adenomas

A

If this occurs pre pubertal- gigantism
Post pubertal - acromegaly
can be bi hormonal (+ve prolactin)

19
Q

What is the clinical presentation for acromegaly?

A 
Appearance: 
prognathism 
brow protrusion 
enlarged hand and feet
large tongue
broad nose

Other:
joint pain , carpel tunnel syndrome, diabetes and deafness

20
Q

What is the pathogenesis of acromegaly?

A

GH secreted from ant pituitary then stimulates liver to secrete insulin like growth factor which is the primary mediator for growth hormone effects.
Acromegaly occurs when there is an excessive, unregulated secretion of GH typically from pit adenoma(somatotropic adenoma).
Other causes- hypothalmic dysregulation and increased secretion of GHRH

21
Q

What are the effects of acromegaly?

A

Tissue expansion
Headache
Visual defects
Cranial nerve palsies

Hormone hypersecretion
Morphological changes - changes in appearance as aforemention and as well as acral swelling, organomegaly, skin tags, colon polyps
Endocrine changes
Metabolic changes eg DM, insulin resistance hypertension , LV hypertrophy
cardiac death

Hypopituitarism
Lethargy, loss of libido, infertility

22
Q

Treatment options for growth hormone adenoma?

A 
Surgery
Radiotherapy
Meds: 
inhibit release of GH 
dopamine agonists:carbegoline 
somatostatin analogues: octreotide, lanreotide 
inhibit GH receptors: pegvisomant

Replacement of pit hormones
Treat co morbidities eg hypertension , DM etc.

23
Q

What are some other adenomas?

A

ACTH producing
•Usually microadenomas
•Silent
•a.w Cushing’s disease (hypercortisolism due to xs ACTH from pituitary)

Gonadotrophic
•Hormonal effects can be subtle
•Can be large

Thyrotrophic
•Rare

Null-cell
•Usually only detected via mass effect when large

24
Q

What are the common causes of hypopituitarism?

A

Adenoma- compression of normal tissue
Trauma
Latrogenic (surgery/radiation)
Ischaemic necrosis (sheehan’s syndrome)

25
Q

What are the rare causes of hypopituitarism?

A

Hypothalamic causes
Empty sella syndrome
Inflammation
Congenital

26
Q

How does hypopituitarism present in adults vs children

A

In adults; can be subtle

in children- delayed sexual development and dwarfism

27
Q

What hormones are released by post pit and their function?

A

Two hormones - released from axonal terminals

Antidiuretic hormone (ADH) synthesized in hypothalamus down nerve axons to post pit 
•Role in controlling the tonicity of extracellular fluid by acting on collecting ducts in kidneys leading to water reabsorption.

Oxytocin
•Contraction of myometrium in labour and stimulates release of milk from lactating breast.

28
Q

What occurs if there is decreased secretion of ADH

A

Diabetes insipidus - polyuria, polydipsia occurs

this can be caused by trauma/head injury/surgical , neoplasm, inflam

endocrine pathology + medicine (4 decks)

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