Endocrine System

Question 1

What’s the interactions between calcium carbonate and levothyroxine and what to do

Answer 1

Calcium carbonate reduces the absorption of levothyroxine resulting in symptoms of hypothyroidism. Take calcium 4 hrs after levothyroxine to avoid interaction

Question 2

What is diabetes insipidus

Answer 2

Damage to pituaitary gland or hypothalamus that secretes vasopressin

Due to lack of ADH (Vasopressin), body can’t retain water so results in polyuria (pissing a lot) and therefore extreme thirst

Question 3

Treatment of diabetes insipidus

Answer 3

Need to replace adh (vasopressin) so mainly desmopressin

If it doesn’t work—> thiazides

Question 4

How desmopressin is better than vasopressin itself

How does vasopressin affect urine to

Answer 4

More potent, longer duration of action, has no vasoconstrictor effect

Makes it more concentrated, Urine will no longer be pale

Question 5

Patient/carer advice for desmopressin

Answer 5

Hyponatreamic comvulsions- those being treated for bedwetting should be warned to avoid fluid overload and stop taking desmopressin when vomiting/diarrhoea

Question 6

3 examples of mineralcorticoids and their s/e

Answer 6

Fludrocortisone, hydrocortisone, corticotrophin, aldosterone

Hypertension, sodium + water retention (increases blood vol so causes htn), potassium + calcium loss

Side effects most marked with fludrocortisone (hence used for postural hypotension) but significant with the others

Question 7

4 examples of glucocorticoids

And side effects

Answer 7

Prednisolone, methyl prednisolone, dexamethasone, betamethasone

Diabetes (hyperglycaemia)
Osteoporosis (danger in elderly…fractures)
Weakly linked to peptic ulcers/perforation… give ppi
Psychiatric reactions

Question 8

How to manage S/E with glucorticoids ( pred, hydro)

Answer 8

Give single dose in morning

Question 9

2 things adrenal cortex secrete

Answer 9

Cortisol (hydrocortisone) which has glucocorticoid activity + weak mineralocorticoid activity

Aldosterone (mineralocorticoid)

In deficiency- give combo of hydrocortisone (replaces cortisol) + fludrocortisone ( replaces aldosterone)

Question 10

What is Addison’s disease

How do we treat it

Answer 10

When adrenal glands don’t secrete cortisol so need to replace cortisol with hydrocortisone

Treat Addison’s with ORAL Hydrocortisone BD

Give higher dose in morning and lower dose at night to mimic normal rhythm of cortisol secretion.

Supplement hydrocortisone with fludrocortisone

Question 11

Why is hydrocortisone unsuitable for long term use

Answer 11

High mineralocorticoid activity causes fluid retention

Also has anti inflammatory properties making it a useful topical steroid for inflammatory skin conditions

Question 12

Activity of dexamethasone and betamethasone

Answer 12

Have very HIGH glucocorticoid activity + insignificant mineralocorticoid activity, therefore suitable for high dose therapy in conditions where fluid retention a disadvantage

Question 13

MHRA warning of corticosteroids

Answer 13

Rare risk of Central serious choriretinopathy of any route of steroids (oral, topical, nasal)—> report any blurred vision/visual disturbances with corticosteroids

Question 14

Side effects, further info of corticosteroids

Answer 14

ADRENAL suppression
After prolonged therapy with steroids —> get adrenal atrophy (wasting) which persists for yrs after stopping
Abruptly stopping steroids causes adrenal insufficiency leading to hypotension/ death so don’t abruptly withdraw if on steroids for > 3 weeks

After taking steroids for long, pituitary gland pathway gets lazy and doesn’t produce as much cortisol, relies on synthetic form

To compensate for diminished adrenocortical response ( adrenal suppression) … need to Increase/Double steroid dose in SURGERY, TRAUMA, INTERCURRENT illness

INFECTIONS
Steroids weaken immune system so increase infection risk, avoid exposure to measles and chickenpox, take varicella zoster vaccine is exposed to chickenpox and never had it

Psychiatric reactions
High dose steroids causes psychiatric reactions like insomnia, suicidal thoughts, euphoria.. stop on reducing or stopping steroid
Use steroids in caution in history/family history of psychiatric reactions
Tell patients to report depression/ suicidal thoughts

Question 15

What do we do to steroid dose in surgery, trauma, intercurrent illness

Answer 15

Temporarily increase dose (double dose)
OR
reintroduce steroid if already stopped

Question 16

Why can’t we abruptly withdraw steroids

Answer 16

Cos after taking steroids for sometime >3weeks, body gets lazy in producing steroids I.e. hydrocortisone, so need to gradually withdraw so body gets used to receiving less steroids and will kick in and produce some more steroids

Abrupt withdrawal leads to adrenal insufficiency which leads to hypotension or death. Also causes cold/flu like symptoms

Question 17

When do you need to gradually withdraw steroid

Answer 17

Taking long term/on High doses

Taking >40mg for > 1 week
Taking evening doses
More than 3 weeks of steroid

Question 18

One exception where you CAN abruptly stop steroids

Answer 18

3 weeks or LESS treatment

Disease unlikely to relapse

High dose steroid can suddenly be brought down to 7.5mg prednisolone as this equates natural adrenal levels

Question 19

Prednisolone doses

Answer 19

Max dose in kids is 60mg for up to 3 days

Copd: 30mg od for 7-14 days
Mild- mod, severe life threatening asthma: 40-50mg OD for 5 days
UC/CD 20-40mg OD until remission