thyroid disease

Question 1

name the hormones involved in the HPT axis’s

Answer 1

TRH
TSH
T3- liothyronine
T4- levothyroxine

Question 2

what is primary thyroid disease?

Answer 2

disease effecting the thyroid gland

Question 3

what is secondary thyroid disease?

Answer 3

disease effecting the pituitary gland

Question 4

what is tertiary thyroid disease/

Answer 4

disease effecting the hypothalamus

Question 5

primary hypothyoidism Myxoedema

Answer 5

decrease in the production of thyroid hormones
v severe
can lead to coma

Question 6

aetiology of primary hypothyroidism

Answer 6

autoimmune disease e.g. hasimoto’s thyroiditis
result of previous hyperthyroidism treatment e.g. surgery
iodine imbalance (uncommon in the UK - freely available in flour, in diet
congenital hypothyroidism

Question 7

what is congenital hypothyroidism ?

Answer 7

child born without a thyroid or with partial thyroid

part of the newborn screening programme

Question 8

symptoms of hypothyroidism

Answer 8

non specific symptoms 
lethargy, weakness\dry scaly skin
sensitive to cold weather\depression\hair loss
memory loss
weight gain
constipation
puffy face (oedema)
and gruff voice with untreated disease

Question 9

Thyroid function tests

Answer 9

TSH levels and
Free unbound T4

test for TPO - rarely measured outside of secondary care

Question 10

what will TFTs show in primary hypothyroidism?

Answer 10

increased TSH - because of low levels of thyroid hormone

decreased free /unbound T4

Question 11

TSH> 10 mU/L and low or free t4

Answer 11

treat with lifelong t4

Question 12

TSH>5- 10 mU/Land low or free t4

Answer 12

treat with lifelong T4

Question 13

TSH>5- 10 mU/L and no low or free t4

Answer 13

Symptoms : 6 month trial of T4, if resolved continue lifelong, if not :check TPO antibody

if no symptoms: check TPO antibody
positive: check TSH annually
negative check TSH 3 yearly

Question 14

what does TPO antibody show

Answer 14

something else affecting TSH levels

Question 15

treatment initial

Answer 15

adult, under 50 - initially 50-100 mag levothyroxine
adjust 25-50 every 3/4 weeks

adult 50+ or those with heart disease - initially 25 mcg once daily, adjusted by 25mcg every 4 weeks

congenital - initially 10- 15 mag/kg (max 50mcg) adjusted by 5mcg every two weeks

measure TSH every 8-12 weeks
since half life of T4 is 7 days
and 3 months after stabilised

Question 16

treatment maintenance

Answer 16

adult : 100-200mcg
children :50-200mcg depending on age and size

monitor every yr adults
monitor every 4-6 months kids
TSH aim (0.5-2)
symptom free
monitor for angina

Question 17

combination treatments

Answer 17

quite rare
difficult unresponsive thyroid disease
no evidence over monotherapy
liothyronine and levothyroxine (t3 and t4)

natural thyroid extracts :
desiccated animal thyroid gland
no evidence on benefit and NOT recommended

Question 18

patient counselling

Answer 18

life long treatment
single daily dose
don’t take at same time as calcium, iron or caffeine

three strength of tablets - cause of confusion
needs for monitoring
primary hypothyroidism - medically exempt for prescription charges

Question 19

aetiology of autoimmune

Answer 19

graves disease
toxic nodules
cancer

Question 20

symptoms

Answer 20

anxious 
palpitations
 tremor
weight loss
tachycardia
goitre
heat intolerance
warm moist skin 
difficulty sleeping
diarrhoea

Question 21

TFT for hyperthyoidism

Answer 21

v high levels of T4 and negligible levels of TSH

Question 22

describe advantages of drug treatment for hyperthyroidism

Answer 22

drug therapy: non invasive
low risk of long term hypo (affects production of hormones
low long term cure rate for non mild disease
rare but desirous side effects

Question 23

who receives drug therapy for hyperthyroidism?

Answer 23

children, pregnancy, breastfeeding
uncomplicated mild disease
acute phase prior to surgery

Question 24

describe briefly drug treatment for hyperthyroidism

Answer 24

drug group: thionamides

main drug (carbimazole)
pregnant and breastfeeding (propylthiouracil)

act by interfering with thyroid hormone synthesis by inhibiting TPO activity in the follicular lumen

Question 25

describe how carbimazole is used to treat hyperthyroidism

Answer 25

1st choice drug start 15-40 mg daily (depends on symptom severity) maintain until TFTs normal (4-8 weeks) maintenance for 12-18 months 25-30% decrease monthly until 5-15 mg important to balance low dose with least/no symptoms mild disease can be corrected by this therapy longer term treatment may be required in relapse C/I in pregnancy as crosses placental barrier

Question 26

blocking replacement regimen

Answer 26

person made completely hypothyroid (temporary) then given thyroxine to replace start on high dose carbimazole for 1 month. (40-60mg) then once all endogenous T3 and T4 is gone add thyroxine 50-100 mcg treat up to 18 months gland returns to normal function when treatment stopped C/I in pregnancy as crosses placental barrier - make child hypothyroid with developmental issues

Question 27

carbimazole and pregnancy

Answer 27

must be used with effective contraception | to prevent pregnancy

Question 28

how is propylthiouracil used to treat hyperthyroidism?

Answer 28

200-400mg initially in divided doses gradually reduced by 50- 150 mg daily preferred in pregnancy, particular 1st trimester intolerant of carbimazole (rash)

Question 29

what is drug induced agranulocytosis ? how is it dealt with

Answer 29

``` abrupt both carbimazole and propylthiouracil can cause bone marrow suppression drop in white cell count 0.3-0.5% not monitored but patient warned ``` patient should report symptoms WBC count performed if evidence of infection carbimazole stopped promptly if there is clinical or lab evidence of neutropenia

Question 30

patient counselling for hyperthyroidism

Answer 30

carbimazole single daily dose propythiouracil divided doses duration of treatment signs of agranulocytosis : sore throat, bruising, mouth ulcer report signs of hepatic dysfuntion advice on contraception if on carbimazole need for regular review , tests patients with hyper are not entitled to free prescriptions

Question 31

Advantages as disadvantages of radioactive iodine

Answer 31

``` non invasive excellent cure rate long term hypothyroidism likely (thyroid cells destroyed by radiation) can worsen eye disease avoid pregnancy/fatherhood ```

Question 32

when is radioactive iodine suitable?

Answer 32

``` 1st line for mild or if drug treatment not suitable toxic nodular goitre relapse after drug treatment comorbid cardiac disease toxic nodular goitre ```

Question 33

surgery for hyperthyroidism: advantages disadvantages when is it suitable?

Answer 33

``` likely long term hypothyroidism excellent and rapid cure rate invasive risk of damage to parathyroid gland scarring and possible swallowing diffuctiies oesophageal obstruction young adults intolerance to drug treatment ```

Question 34

why can't you start iodine therapy or surgery straight after diagnosis? what do you do instead

Answer 34

prevent thyrotoxic crisis (medical emergency due to dangerously high levels of T4 released into system : causes dehydration, HR over 140 bpm, hypotension, GI side effects confusion agitation delirium psychosis seizure and coma make patient euthyroid using drugs

Question 35

adjuvant treatment for hyperthyroidism

Answer 35

high dose of beta blockers for cardio side effects for a initial months propanalol nadolol TDS/QDS rapid relief of symptoms e.g tremor C/I in asthma

Question 36

which drugs cause drug induced thyroid disease?

Answer 36

iodine ,amiodorone, and lithium can cause hyper or hypo iodine overdose: inhibit/supress T3/t4 release/ production

Question 37

how can iodine cause drug induced thyroid disease?

Answer 37

iodine overdose: inhibit/supress T3/t4 release/ production rarely can cause thyrotoxocis if underlying auto regulation deficiency can cause hypo due to being unable to produce T3/T4

Question 38

how can amiodorone cause drug induced thyroid disease?

Answer 38

used to treat arrthymias contains organic iodide hypothroidism can occur in at any time 1-10\5 patients inhibits synthesis and release of thyroid hormones continue amiadorone and start T4 replacement therapy mild hypo blocks conversion of t4 to t3, inc in TSH and T4 (usually transient when start amiodorone and normalises within 4 months) severe hyper: inc production of t4 because of iodine direct thyroiditis excessive release of t4 into circulation, withdraw therapy

Question 39

how does lithium cause drug induced thyroid disease?

Answer 39

Hypothyroidism: inhibits uptake and prevents T3,T4 release can be transient and subclinical monitor TSH start replacement t4 therapy Hyperthyroidism rare paradoxical effect stop treatment