Histo: Endocrine disease Pt.1

Question 1

What types of cell are the anterior and posterior pituitary made up of?

Answer 1

Anterior = epithelial cells (derived from developing oral cavity)

Posterior = nerve cells

Question 2

What is the blood supply to the anterior pituitary?

Answer 2

Pituitary portal system

Question 3

Where do the nerves that make up the posterior pituitary originate?

Answer 3

Paraventricular nucleus
Supraoptic nucleus

Question 4

What are the 3 symptoms catergories of pituitary disease?

Answer 4

• Hyperpituitarism symptoms - due to excess hormone secretion
• Hypopituitarism symptoms - due to deficiency of hormone secretion
• Mass effect symptoms

Question 5

What is the most common cause of hyperpituitarism?

Answer 5

Functional adenoma

• Orignally classified by morphology of predominant cell type (e.g. acidophil, basophil, chromophobe)
• Now classified by hormone produced

Question 6

What is the most common type of pituitary adenoma?

Answer 6

Prolactinoma

Question 7

What is a microadenoma?

Answer 7

A pituitary adenoma with a diameter < 1 cm

Question 8

Outline the clinical features of prolactinoma.

Answer 8

• Amenorrhoea
• Galactorrhoea
• Loss of libido
• Infertility

Question 9

What are the clinical manifestations of growth hormone adenomas?

Answer 9

• Gigantism (prepubertal children)
• Acromegaly (adults)
• Diabetes
• Muscle weakness
• Hypertension
• Heart failure

Question 10

What disease is caused by corticotroph cell adenomas?

Answer 10

Cushing’s disease

Question 11

List some causes of hypopituitarism.

Answer 11

• Non-secretory pituitary adenoma
• Ischaemic necrosis
• Iatrogenic (surgery, radiotherapy)

Question 12

What is the most common cause of ischaemic necrosis of the pituitary gland?

Answer 12

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

Question 13

List some clinical features of hypopituitarism.

Answer 13

• Growth failure in children (pituitary dwarfism)
• Gonadotrophin deficiency - amenorrhoea and infertility (women); impotence and loss of libido (men)
• Hypothyroidism and hypoadrenalism
• Prolactin deficiency - failure of post-partum lactation

Question 14

Which hormones are produced by the posterior pituitary?

Answer 14

ADH and oxytocin

Question 15

Which conditions involve ADH?

Answer 15

Diabetes insipidus

SIADH

Question 16

List some consequences of the local mass effect of pituitary tumours.

Answer 16

• Bitemporal hemianopia (optic chiasm)
• Headaches (raised ICP)
• Obstructive hydrocephalus

Question 17

Describe the histological appearance of the thyroid gland.

Answer 17

• 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

Question 18

Describe the physiological response of the thyroid gland to TSH.

Answer 18

• Stimulating of TSH receptors leads to pinocytosis of the colloid 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

Question 19

Which hormone do parafollicular cells produce?

Answer 19

Calcitonin - this promotes the absorption of calcium by the skeletal system

Question 20

What is a non-toxic goitre?

Answer 20

Enlargement of the thyroid gland without overproduction of thyroid hormones

Question 21

What is the most common cause of non-toxic goitre?

Answer 21

Iodine deficiency - leads to impaired thyroid hormone synthesis

Other causes involves hereditary enzyme defects

Question 22

List some primary and secondary causes of thyrotoxicosis.

Answer 22

Primary

• Graves’ disease
• Toxic multinodular goitre/adenoma
• Thyroiditis

Secondary

• TSH-secreting pituitary adenoma (rare)

Question 23

List some causes of thyrotoxicosis that are not associated with the thyroid gland.

Answer 23

• Struma ovarii - ovarian teratoma with ectopic thyroid hormone production
• Factitious thyrotoxicosis - exogenous thyroid hormone intake

Question 24

What is the most common cause of endogenous hyperthyroidism?

Answer 24

Grave’s disease

Question 25

Which antibodies are often seen in Graves’ disease?

Answer 25

• TSH receptor
• Thyroglobulin (TG)
• Thyroid peroxidase (TPO)