Endocrinology Flashcards
Define endocrinology
Study of hormones (+ their gland of origin), receptors, intracellular signalling pathways, + associated diseases
Describe insulin activation
- Binds to insulin receptors
- Results in phosphorylation of receptor + activation of secondary messenger - TYROSINE KINASE
- Phosphorylation of signal molecules
- Cascade of effect
- Glucose uptake
Give 3 examples of amine hormones
Dopamine, adrenaline, noradrenaline
Is T3 or T4 more active?
T3
Is T3 or T4 more abundant in the body?
T4
Where do peptide hormones bind?
Receptors on cell membrane
Where do steroid hormones bind?
Cytoplasmic receptors
Normal blood glucose?
3.5-8.0 mmol/L
Why is the brain the MAIN consumer of glucose?
FFAs can’t cross the BBB so the brain can’t convert them into ketones (–> acetyl-CA for Krebs)
Pathophysiology of DKA
- Hyperglycaemia –> osmotic diuresis
- More peripheral lipolysis –> more FFAS
- More acetyl-CoA –> more ketones
- Metabolic acidosis –> vomiting
- Dehydration impairs renal excretion of H+ + ketones
- pH-dependent processes impaired
- Worsened by ‘stress hormones’
Define ketoacidosis
A state of uncontrolled catabolism associated with insulin deficiency
What is hyperosmolar hyperglycaemia?
Life-threatening emergency characterised by marked hyperglycaemic, hyperosmolality, + mild/no ketosis
What is the metabolic emergency characteristic of uncontrolled T2DM?
Hyperosmolar hyperglycaemic state
Give 3 possible presentations of pituitary tumour
Pressure on local structures - e.g. bitemporal hemianopia
Pressure on normal pituitary - HYPOpituitarism
Functioning tumour - HYPERpituitarism
List 3 functioning tumours (hyperpituitarism)
Prolactinoma
Acromegaly
Cushing’s
Give 5 possible causes of hyperthyroidism
Grave’s disease
Toxic multinodular goitre
Solitary toxic adenoma (benign)
De quervain’s thyroiditis (post-viral)
Drug-induced hyperthyroidism
Treatment of Graves’ opthalmopathy?
IV methylprednisolone
Causes of primary hypothyroidism?
Primary atrophic hypothyroidism (PAH)
Hashimoto’s thyroidits
Postpartum thyroiditis
Iatrogenic (thyroidectomy, radioactive iodine therapy)
Drugs (e.g. carbimazole, lithium, amiodarone)
Iodine deficiency
Cause of secondary hypothyroidism?
Hypopituitarism
Most common cause of hypothyroidism?
Primary atrophic hypothyroidism (PAH)
What drug can cause both hyperthyroidism + hypothyroidism?
Amiodarone
Main complication of hypothyroidism?
Myxoedema coma
Most common type of thyroid carcinoma?
Papillary
Clinical presentation of thyroid carcinoma?
Thyroid nodules
Thyroid gland increases in size, becomes hard, + is irregular in shape
Dysphagia
Hoarse voice
Treatment of thyroid carcinoma?
Levothyroxine (T4)
Thyroidectomy
What is the most common hormonal disturbance of the pituitary?
Hyperprolactinemia
Causes of hyperprolactinemia?
Prolactinoma
Pituitary stalk damage
Drugs
Pregnancy
Stress
What is hyperprolactinemia?
Too much prolactin in the blood of women who aren’t pregnant + in men
Treatment for adrenal crisis?
IV hydrocortisone
What is serum calcium controlled by?
PTH + vitamin D
Is hypercalcaemia or hypocalcaemia more common?
Hypercalcaemia
What is calcitriol stimulated by?
Low plasma calcium
Low plasma phosphate
PTH
K+ levels for hypokalaemia?
Serum K+ <3.5 mmol/L
(>2.5 mmol/L is a MEDICAL EMERGENCY)
Describe carcinoid tumours
These tumours originate from the enterochromaffin cells (neural crest) + are capable of producing serotonin
What is carcinoid crisis?
When a caricnoid tumour outgrows its blood supply mediators flow out + this is LIFE-THREATENING
Treatment of carcinoid crisis?
High dose somatostatin analogue (e.g. octreotide)
Sulphonylureas: examples + indications
Gliclazide
T2DM
Glitazones: examples
Pioglitazone
Glitazones: mechanisms
Activates PPARs which bind FFAs + induce genes that enhance insulin action
Antithyroid drugs: examples + indications
Carbimazole
Grave’s + before thyroid surgery
Antithyroid drugs: mechanisms
Prevents thyroid peroxidase from iodinating tyrosine residues so reduces production of T3 + T4
GH receptor antagonists: examples + indications
Pegvisomant
Acromegaly
GH receptor antagonists: mechanisms
Blocks action of GH at its receptor to reduce production of IGF-1
Vasopressin antagonists: examples + indications
Tolvaptan
Euvolemic/Hypervolemic hyponatraemia
Vasopressin antagonists: mechanisms
Inhibits V2 so increases fluid excretion
Vasopressin analogue: examples + indications
Desmopressin
DI + distinguish cranial from nephrogenic DI
Adrenal corticosteroid inhibitors: examples
Metyrapone
Cushing’s + diagnose adrenal insufficiency
Adrenal corticosteroid inhibitors: mechanisms
Blocks cortisol synthesis by reversibly inhibits the enzyme that stimulates ACTH secretion
Adrenal corticosteroid inhibitors: SEs
GI disturbances
Headache
Dizziness
Drowsiness
What is a NFPA?
Benign tumour of the pituitary which doesn’t produce excess hormones
