63 - Diseases of the endocrine system

What do acinar cells of the pancreas secrete?

Digestive enzymes (exocrine)

What are neurocrine hormones?

Secretion of hormones into the bloodstream by neurons

What are endocrine hormones?

Secretion of hormones into the bloodstream by endocrine glands

What are paracrine hormones?

Hormones secreted by one cell that affects adjacent cells

What are autocrine hormones?

Hormones secreted by a cell that affects itself

What hormones does the posterior pituitary release?

- ADH

- Oxytocin

What hormones does the anterior pituitary release?

- TSH

- ACTH

- FSH and LH

- Growth hormone

- Prolactin

- Endorphins

Are pituitary tumours most commonly benign or malignant?

- Benign: adenoma

- Usually causes pressure due to growth (optic chiasm)

What are the symptoms of a pituitary adenoma?

- Bitemporal hemianopia

- Excess hormone production

What mutation causes prolactinomas?

Lactotroph

What are the symptoms of excess prolactin?

- Galactorrhea

- Gynecomastia

- Amenorrhoea

- Infertility

What are the symptoms of excess growth hormone?

- Acromegaly

- Gigantism

What is acromegaly?

Rare condition resulting from excess secretion of growth hormone (GH)

Does glucose inhibit or stimulate growth hormone secretion?

Inhibits

What test confirms acromegaly?

Oral glucose suppression test

What is the hypothalamic-pituitary-thyroid axis?

1) Hypothalamus releases TRH

2) TRH stimulates TSH from the anterior pituitary

3) TSH stimulates the thyroid to release T3 and T4

4) Negative feedback system

What is the most common cause of hypothyroidism?

Hashimoto's thyroiditis

What are other causes of hypothyroidism?

- Iodine deficiency

- Post-radioiodine therapy

- Post surgery

What is cretinism?

Congenital hypothyroidism

What are the clinical manifestations of hypothyroidism?

- Hypothermia

- Bradycardia

- Periorbital oedema

- Weight gain

- Fatigue

- Cold intolerance

- Constipation

- Hoarse voice

What is the most common cause of hyperthyroidism?

Graves' disease

What are the clinical manifestations of Graves' disease?

- Goitre

- Hair loss

- Bulging eyes

- Tachycardia

- Heat intolerance

- Clammy

What is multinodular goiter (MNG)?

Enlarged thyroid gland with multiple nodules

What are the risks of a multinodular goiter (MNG)?

- Tracheal compression

- Dysphagia

What is Plummer's disease?

Toxic multinodular goiter - hyperthyroidism

What is a thyroid follicular adenoma?

- Solid mass with a fibrous capsule

- Wide age range, more commonly women

What is a thyroid follicular carcinoma?

- Well differentiate malignant tumour with good prognosis

- Can invade capsule and blood vessels

What is a papillary thyroid carcinoma?

- Well differentiated carcinoma with excellent prognosis

- Invades lymphatics and spreads to local lymph nodes

- Mainly younger female patients

What is the parathyroid hormone cycle?

1) Hypocalcaemia increases PTH secretion

2) PTH stimulates the kidney to:

- decrease calcium excretion

- increase phosphate excretion

- activate vitamin D to calcitriol

3) PTH stimulates osteoclast activity to break down bone tissue which increases releases calcium and phosphate

4) Calcitriol stimulates the intestines to increase calcium and phosphate absorption

5) Negative feedback system

What are the primary causes of hyperparathyroidism?

- Adenoma/carcinoma

- MEN1 or MEN2a gene

What are the secondary causes of hyperparathyroidism?

- Renal failure

- Vitamin D deficiency

What are the clinical manifestations of hyperparathyroidism?

- Renal stones

- Muscle weakness

- Thirst

- Constipation

- Anorexia

- Tiredness

What are the different layers of the adrenal cortex?

GFR-ACD

- Zona glomerulosa: aldosterone (mineralcorticoid)

- Zona fasciculata: cortisol (glucocorticoid)

- Zona reticularis: DHEA (androgen)

What does the adrenal medulla release?

Catecholamines

What cells release catecholamines?

Chromaffin cells

What is Cushing's syndrome?

Endocrine disorder die to excess cortisol

What are the clinical manifestations of Cushing's syndrome?

- Weight gain

- Visceral obesity

- Moon shaped face

- Slender arms and legs

- Buffalo hump

- Amenorrhea

- Acne

- Hyperglycaemia

What is Conn's syndrome?

Hyperaldosteronism

What are the clinical manifestations of Conn's syndrome?

- High BP

- Muscular weakness

- Muscle spasms

- Excess urination

- Arrhythmias

What is Waterhouse-Friderichsen syndrome?

Adrenal hemorrhage which results in primary adrenal insufficiency, usually due to a severe bacterial infection (meningitis)

What is Addison's disease?

- Primary adrenal insufficiency

- Autoimmunity most common cause

What are the clinical manifestations of Addison's disease?

- Hyperpigmentation

- Hypotension

- Hyponatraemia

- Vomiting

- Constipation

What is pheochromocytoma?

Tumour of the adrenal medulla - produces excess catecholamines

What are the clinical manifestations of pheochromcytoma?

- Tachycardia

- Headache

- Pallor

- Sweating

- Hypertension