Endocrinology Flashcards
What is primary hypothyroidism caused by?
Problems with the thyroid gland
What is secondary hypothyroidism caused by?
Problems with the pituitary gland
What is tertiary hypothyroidism caused by?
Problems with the hypothalamus
What are the three lobes of the anterior pituitary gland?
- Anterior (distalis, tuberalis)
- Intermediate (intermedia, nervosa)
- Posterior (nervosa, infundibulum)
Where does the pituitary gland sit?
Pituitary fossa in sphenoid bone
What can cause bitemporal hemianopia?
Compression of optic chasm due to a sella/suprasellar mass
What are the 6 hormones of the anterior pituitary?
ACTH, GH, PRL, TSH, FSH, LH
How does endocrinopathology clinically present?
Mass lesion (headache, vision problems) Hypopituitarism (fatigue, weight gain etc.)
How is pituitary hypo function tested?
Measure pituitary hormone
Measure target hormone
Insulin tolerance test
What does high TSH indicate in hypothyroidism?
Primary hypothyroidism (thyroid gland)
What does low TSH indicate in hypothyroidism?
Secondary hypothyroidism (pituitary gland)
Why are prolactin levels high in pituitary tumour patients?
Pituitary tumours prevent dopamine production - dopamine normally inhibits
prolactin production
What are the classes of pituitary tumour?
Size (microadenoma vs macro adenoma)
Functioning vs non functioning
What does a GH functioning tumour present as?
Acromegaly
What does an ACTH functioning tumour present as?
Cushing’s syndrome
What does a PRL functioning tumour present as?
Galactorroea (milk production outside of pregnancy)
Amenorrhoea
What does a TSH functioning tumour present as?
Thyrotoxicosis (hyperthyroidism)
What is the treatment for a pituitary tumour?
Conservative
Surgery
Medical
Radiotherapy
Which hormones are tyrosine derivatives?
Dopamine
Thyroxine
Adrenaline/noradrenaline
Which proteins are glycoproteins?
TSH
LH
FSH
hCG
Which hormones are steroid hormones?
Mineralocorticoids
Glucocorticoid
Sex steroids
Which 3 hormones does the thyroid gland produce?
Calcitonin
T3
T4
How do catecholamines and peptide hormones circulate?
Free form (hydrophilic)
How do thyroid hormones and steroid hormones circulate?
In a bound form (hydrophobic)
How are catecholamines and peptide hormones stored?
Secretory granules/vesicles
How are thyroid hormones stored?
In colloid as part of thyroglobulin
How are steroid hormones stored?
Not stored (made on demand)
Which 2 hypothalamic hormones control prolactin release?
- Thyrotropin releasing hormone (excitatory)
2. Dopamine (inhibitory)
How does suckling result in oxytocin release?
Activation of nipple mechanoreceptors –> inhibits dopamine release –> activates neutrons producing oxytocin
What is hyperprolactinaemia?
High prolactin levels
Symptoms: galactorrhea, gynaecomastia, infertility
Treated with D2 agonits.
At what stages of life does the thyroid gland enlarge?
Adolescence
Pregnancy/lactation
At end of menstrual cycle
What is the blood supply to the thyroid gland?
Superior and inferior thyroid arteries (from external carotid and subclavian)
Which gland concentrates iodine in the body?
Thyroid gland
What is the mechanism of action of thyroid hormones?
Interaction with nuclear receptors
What are some symptoms of hypothyroidism?
Cold intolerance
Weight gain
Constipation
What are possible causes of hypothyroidism?
Hashimoto’s thyroiditis
Also chemo/hyper treatment
What levels of of TSH, T4 and T3 indicate Hashimoto’s thyroiditis?
TSH - high
fT4 - low
T3 - low
What is a goitre?
Increase in size of thyroid gland often due to iodine deficiency
What are some symptoms of hyperthyroidism?
Sweating
Heat intolerance
Fatigue
Eye protrusion
What are possible causes of hyperthyroidism?
Graves’ disease (most common)
Could also be toxic thyroid nodule/tumour
How is Graves’ disease diagnosed?
Antibodies/thyroid uptake scan
How is hyperthyroidism treated?
Antithyroid drugs/radioiodine/surgery
How is cortisol synthesis regulated?
Hypothalamus releases CRH –> corticotrophs in anterior pituitary release ACTH –> adrenal cortex makes cortisol
What are the effects of cortisol?
Hyperglycaemia
Muscle wasting
Osteoporosis
What are some disadvantages of steroids?
Can suppress immune response
Can contribute to osteoporosis
Can cause iatrogenic Cushing’s syndrome
What is Addison’s disease?
Chronic adrenal insufficiency (hypo function).
What is primary adrenal insufficiency?
Destruction of adrenal cortex (lack of cortisol)
What is secondary adrenal insufficiency?
Lack of ACTH
What are the clinical features of Addison’s disease?
Weakness/fatigue
Hyperpigmentation
Postural hypotension
GI disturbances
What are signs of malignant nodules of thyroid on US?
Microcalcification
Hypoechoic
Solid/large
Irregular margin
What are risk factors for thyroid cancer?
Radiation exposure
Family history
Hashimoto’s thyroiditis
Cowden’s syndrome
How does thyroid cancer clinically present?
Lump in neck with sudden pain
Enlarging mass
Unexplained hoarse voice
What is pheochromocytoma?
A rare tumour of the adrenal medulla, which secretes noradrenaline/adrenaline.
What is Conn’s syndrome?
Too much aldosterone (often caused by benign adrenal adenoma)
