endocrine system

Question 1

what are the main endocrine glands?

Answer 1

Hypothalamus/Pituitary
Thyroid
Parathyroid
Pancreas
Adrenal
Ovaries/testicles

Question 2

what are the two functional lobes of the pituitary and their general function?

Answer 2

Anterior pituitary
produces various hormones

Posterior pituitary
stores various hormones

Question 3

which hormones do the anterior pituitary gland produce?

Answer 3

Growth hormone (GH)
Adrenocorticotrophic hormone (ACTH)
Gonadotrophins (FSH and LH)
Thyroid stimulating hormone or thyrotrophin (TSH)
Prolactin (PRL)

Question 4

what does growth hormone do?

Answer 4

For skeletal growth

Question 5

what does ACTH do?

Answer 5

Stimulates the adrenals to produce steroids

Question 6

what do gonadotrophins do?

Answer 6

Stimulate the testicles or ovaries to produce sex hormones

Question 7

what does TSH do?

Answer 7

Stimulates the thyroid to produce thyroid hormones

Question 8

what does prolactin do?

Answer 8

Stimulates breast milk production

Question 9

what does the posterior pituitary gland do?

Answer 9

stores the hormones produced in the hypothalamus

Question 10

which hormones does the posterior pituitary produce?

Answer 10

Antidiuretic hormone (ADH)
Oxytocin

Question 11

what is the anterior pituitary controlled by?

Answer 11

the hypothalamus

Question 12

what stimulates ACTH secretion?

Answer 12

corticotrophin releasing hormone

Question 13

what stimulates GH secretion?

Answer 13

growth hormone releasing hormone

Question 14

what stimulates TSH secretion?

Answer 14

thyotropin releasing hormone

Question 15

what stimulates FSH and LH secretion?

Answer 15

gonadotrophin releasing hormone

Question 16

how is prolactin controlled?

Answer 16

inhibitory effect from the hypothalamus

Question 17

how are pituitary hormones switched off?

Answer 17

negative feedback from hormone

Question 18

which glands are not controlled by the pituitary?

Answer 18

Adrenal medulla - Produce adrenaline and noradrenaline
Parathyroid - Controls calcium levels
Pancreas - Controls sugar levels

Question 19

what is the thyroid composed of?

Answer 19

Midline isthmus (just below the cricoid cartilage)
Right lobe
Left lobe

Question 20

how is the thyroid gland arranged?

Answer 20

Thyroid cells are arranged in follicles and produce thyroid hormones
The thyroid also contains C cells, which produce calcitonin (calcium metabolism)

Question 21

what is calcium metabolism mainly controlled by?

Answer 21

4 parathryoid glands sitting behind the thyroid

Question 22

which other organs are involved in the metabolism of calcium?

Answer 22

Kidneys
Calcium excretion and production of active vitamin D

Gut
Absorption of calcium

Bone
Storage of calcium

Thyroid

Question 23

what are the two areas of the adrenal gland and what do they produce?

Answer 23

Adrenal cortex, 90% of the gland and produces:
Cortocosteroids (cortisol)
Androgens (male hormones)
Mineralocorticoid (aldosterone)

Adrenal medulla, 10% of the gland and produces:
Catecholamines (adrenaline, noradrenaline and dopamine)

Question 24

which adrenal hormones are not controlled by the pituitary?

Answer 24

Catecholamine secretion is not controlled by the pituitary (related to blood pressure)

Mineralocorticoid secretion is not controlled by the pituitary (related to renin-angiotensin system, which controls the blood pressure)

Question 25

what can a static test be used to diagnose?

Answer 25

abnormalities of thyroid and sex glands

Question 26

what can stimulation tests be used to diagnose?

Answer 26

suspected hormonal under-secretion where a static test is not enough

Question 27

what are suppression tests used to diagnose?

Answer 27

some hormonal over-secretion Examples include: Giving steroids and testing for endogenous steroid production (external steroids should switch off internal steroid production) Giving glucose and testing GH secretion (glucose switches off GH secretion in normal individuals)

Question 28

what is the clinical presentation of prolactin oversecretion and what is it normally due to?

Answer 28

Usually due to a pituitary tumour secreting prolactin (prolactinoma) Clinical presentation Galactorrhoea (breast milk production) Amenorrohoea in women and sexual dysfunction in men Headaches and visual field problems in large tumours

Question 29

what can mildly raise prolactin levels?

Answer 29

``` Sexual intercourse Nipple stimulation Stress Large number of drugs Non-functioning pituitary tumour ```

Question 30

how does GH oversecretion manifest in children?

Answer 30

Excessive growth spurt and increased size of feet and hands | If left untreated growth hormone excess leads to gigantism, the most serious consequence of the disease

Question 31

how does GH oversecretion manifest in adults?

Answer 31

Acromegalic face Wide and large hands/feet Increased sweating (common complaint)

Question 32

how do you diagnose GH oversecretion?

Answer 32

Suppression tests are necessary Glucose is given, followed by GH measurements at different time points. In healthy individuals, glucose suppresses GH production and hence plasma levels of the hormones fall but not in those with oversecretion. Imaging is necessary to confirm the presence of pituitary tumour

Question 33

what can Cushings syndrome be caused by?

Answer 33

Pituitary secreting ACTH tumour (Cushing’s disease) Adrenal tumours secreting cortisol Cancers producing ACTH

Question 34

how do you diagnose Cushings?

Answer 34

Static tests are not enough and suppression tests are required. Dexamethasone suppression test is used to confirm the failure to suppress endogenous cortisol production.

Question 35

what are the two types of hyperthyroidism?

Answer 35

Primary hyperthyroidism Very common, RA sees 2 patients/week! ``` Secondary hyperthyroidism (pituitary TSH secretion) Rare; RA had seen 4 patients in his career so far! ```

Question 36

what is hyperthyroidism caused by?

Answer 36

Graves’ disease (80%). Autoimmune condition Toxic nodule or toxic MNG (15%). Thyroiditis (1%). Drug induced (amiodarone)

Question 37

clinical presentation of hyperthyroidism?

Answer 37

Hyperactivity, irritability, insomnia Heat intolerance and increased sweating Palpitations Weight loss despite overeating Menstrual problems

Question 38

what are the signs of thyrotoxicosis?

Answer 38

Hand tremor Inceased sweating Fast pulse

Question 39

what are extrathyroidal signs of hyperthyroidism?

Answer 39

Swelling round the eyes Protrusion of the eye ball (proptosis) Paralysis of eye muscles

Question 40

can a static test be used for hyperthyroidism?

Answer 40

yes

Question 41

how do you treat hyperthyroidism?

Answer 41

Anti-thyroid drugs: disease remission in 50% of patients after treatment for 6-18 months can suppress white cell production (very rare) Radioactive iodine Destroys the thyroid gland Surgery

Question 42

how does GH deficiency manifest?

Answer 42

Children Failure of growth Adults Nothing Tiredness Depression

Question 43

how do you test for GH deficiency?

Answer 43

Glucagon stimulation test | Insulin stress test (lowers blood glucose, stressing the body and forcing growth hormone secretion)

Question 44

what may steroid under-secretion be due to?

Answer 44

Adrenal failure | Pituitary failure

Question 45

how does steroid under-secretion present?

Answer 45

Failure to grow in children Severe tiredness Dizziness due to low blood pressure Abdominal pain, vomiting an diarrhoea

Question 46

how do you test for steroid under-secretion?

Answer 46

Synacthen test (giving ACTH) if primary adrenal failure is suspected GST or IST if secondary adrenal insufficiency is suspected

Question 47

what is primary hypothyroidism caused by?

Answer 47

thyroid failure and inability to produce thyroid hormones (common).

Question 48

what is secondary hypothyroidism caused by?

Answer 48

failure to produce TSH (rare).