Endocrine

Question 1

4 Releasing hormones

Answer 1

GnRH (gonadotrophin releasing hormone)
GHRH (growth hormone releasing hormone)
TRH (Thyrotropin releasing hormone)
CRH (cortico tropin releasing hormone)

Secreted into hypophyseal system

Question 2

2 release inhibiting hormones

Answer 2

Dopamine
Somatostatin
Secreted into hypophyseal system

Question 3

The only non neuropeptide hypothalamic hormone

Answer 3

Dopamine

Question 4

2 Posterior pituitary hormones

Answer 4

Vasopressin

Oxytocin

Question 5

Most common cause of pituitary disease and a common co-morbidity

Answer 5

90% are caused by adenoma’s (benign pituitary tumours

Vision loss caused by compression of optic chiasm

Question 6

Hypopituitarism

Answer 6

Rare, usually caused by tumours
Managed with appropriate replacement hormones
Symptoms the same as if the target endocrine organ hormone deficiency

Question 7

Thyroid hormones - differences

Answer 7

Tri-iodothyroxine (T3)
Thyroxine (T4) -90% of total
Different only in the no of iodine residues
T4 has lower affinity for target but longer half life

Question 8

Conversion of T4 to T3

Answer 8

T4 converted by type 1 and 2 deiodinases in peripheral tissues

Question 9

Thyroid blood protein binding

Answer 9

At equilibrium 0.4% of T3 is free and 0.04% of T4
Bound to TGB, TTR and TBP
T3 binds with lower affinity to plasma protein and diffuses more rapid from capillary to cell

Question 10

Deiodonases (DI/DII/DIII aka type 1/2/3)

Where and what do they do?

Answer 10

DI- Found in liver/kidneys. Can deiodonate both rings
DII-Found in heart, muscle, CNS, fat, pituitary. Can only deiodonate the outer ring and is the major activating enzyme
DIII- Found in foetal tissue, placenta and brain (except pituitary). Can only deiodonate inner ring and is a major inactivating enzyme

Question 11

Purpose of thyroid hormones

Answer 11

Regulates BMR and enhances the actions of catecholamines (due to upregulation of beta-adrenoreceptors)

Question 12

Hypothyroidism

Answer 12

Common (2% in women, 0.1% in men)
Usually caused by disease of thyroid gland but can also be lack of TSH
Most common form is autoimmune hypothyroidism

Question 13

Signs and symptoms of hypothyroidism

Answer 13

Tiredness, weight gain, cold intolerance, goitre, slowness, dry skin, dry and thin hair, bradycardia and slow relaxing reflexes

Question 14

Hypothyroidism: D and M

Answer 14

Serum TSH levels elevated (confirms primary hypothyroidism) low t4 will exclude secondary hypothyroidism
Replacement therapy with levothyroxine

Question 15

Hyperthyroidism

Answer 15

Common, 2-5% of females 
Thyroid disease is 99% of cases 
Graves disease is most common form 
-Autoimmune caused by stimulating TSH antibodies)
-Many patients undergo relapse/remission 
-Many become hypothyroid 
-Eye complaints 
Can be induced by amiodarone

Question 16

Hyperthyroidism: Signs and symptoms

Answer 16

Weight loss, increased appetite, irritability, Tremor, Heat intolerance, Tremor, hyperkineses, Tachycardia, lid lag and stare

Question 17

Hyperthyroidism: D and M

Answer 17

TSH< 0.05mU/L
Elevated T3/T4 confirms diagnosis
thyroid peroxidase and thyroidglobulin is usually present
Offer antithyroid drugs (carbimazole)
Radioiodine- not for preggos or breast feeding
Surgery
Beta-blockers for suppression of tachycardia and atrial fibrillation. Also stops t4>t3

Question 18

Goitre (thyroid enlargement)

Answer 18

Separable into diffuse and nodular types

Usually benign though can cause anxiety so will be treated with surgery or radioactive iodine