Histo: Endocrine disease Flashcards
What types of cell are the anterior and posterior pituitary made up of?
Anterior = epithelial cells
Posterior = nerve cells
What is the blood supply to the anterior pituitary?
Pituitary portal system
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Where do the nerves that make up the posterior pituitary originate?
Supraoptic nucleus and paraventricular nucleus
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Describe the histology of the anterior pituitary.
Made up of epithelial cells derived from the developing oral cavity
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How is hyperpituitarism defined?
Excess secretion of the trophic hormones (hormones released by anterior pituitary) - e.g. TRH, LH, FSH, GH, ACTH, PRL)
immunohistochemical diagnosis
What is the most common type of pituitary adenoma?
Prolactinoma
What is a microadenoma?
A pituitary adenoma with a diameter < 1 cm
Outline the clinical features of prolactinoma.
- Amenorrhoea
- Galactorrhoea
- Loss of libido
- Infertility
What are the clinical manifestations of growth hormone adenomas?
- Gigantism (in prepubertal children)
- Acromegaly (in adults)
- Diabetes, Muscle weakness, Congestive HF, HTN
What disease is caused by corticotroph cell adenomas?
Cushing’s disease
List some causes of hypopituitarism.
- Non-secreting pituitary adenoma
- Ischaemia
- Iatrogenic (e.g. surgery, radiotherapy)
What is the most common cause of ischaemic necrosis of the pituitary gland?
Sheehan’s syndrome - the pituitary enlarges during pregnancy and is more susceptible to ischaemia. A post-partum haemorrhage may induce ischaemia.
Other causes: DIC, sickle cell anaemia, shock
List some clinical features of hypopituitarism.
Children – growth failure (pituitary dwarfism)
Gonadotrophin deficiency:
* Amenorrhoea and infertility in women
* Decreased libido and impotence in men
TSH and ACTH deficiency – secondary hypothyroidism and secondary hypoadrenalism
Prolactin deficiency – failure of post-partum lactation
Which hormones are produced by the posterior pituitary?
ADH and oxytocin
Which clinical syndrome involves ADH?
Diabetes insipidus
SIADH
List some consequences of a local mass effect of pituitary tumours.
- Bitemporal hemianopia (optic chiasm)
- Headaches (raised ICP)
- Obstructive hydrocephalus
Describe the histological appearance of the thyroid gland.
- Arranged into follicles with a small amount of stromal tissue between them
- They are lined by epithelial cells and have a large amount of colloid in the middle
- Parafollicular cells are found between the follicles
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Describe the physiological response of the thyroid gland to TSH.
- Stimulating of TSH receptors leads to pinocytosis of the colloid (to intake thyroxine) by the thyroid follicular cells AND promotes the conversion of thyroglobulin into T3 and T4
- Release of thyroid hormones into the circulation results in a rise in basal metabolic rate
Which hormone do parafollicular cells produce?
Calcitonin - this promotes the absorption of calcium by the skeletal system to reduce calcium levels
What is a non-toxic goitre?
Enlargement of the thyroid gland without overproduction of thyroid hormones
What is the most common cause of non-toxic goitre?
- Commonly caused by impaired thyroxine production due to Iodine deficiency (Higher rates in developing countries)
- NOTE: bassicas (e.g. cabbages) interfere with thyroid hormone synthesis
- It may also be caused by a hereditary enzyme deficiency
List some primary causes of thyrotoxicosis.
- Graves’ disease
- Hyperfunctioning multinodular goitre/adenoma
- Thyroiditis
List some pathological causes of thyrotoxicosis that are not associated with the thyroid gland.
- Struma ovarii - ovarian teratoma with ectopic thyroid hormone production
- Factitious thyrotoxicosis - exogenous thyroid hormone intake
Which antibodies are often seen in Graves’ disease?
Antibodies to the TSH receptor and thyroglobulin