Thyroid - Hashimoto, Graves, Subacute, Riedel, Postpartum, Drug-induced, Toxic multinodular goitre, Thyroid storm, Myxedemic coma, Subclinical

Question 1

Structure and function of thyroid gland

Answer 1

Under thyroid and cricoid cartilage
Wraps around trachea

R, P, L lobe

TRH => TSH => T3, T4, synthesis
Calcitonin

T4, stable prohormone
- DIT + DIT = thyroid peroxidase=> T4
- TBG, TBPA bound

T3, active metabolite
- DIT + MIT = thyroid peroxidase=> T3
- T4 also metabolized in periphery
- TBG, albumin bound

Calcitonin
-released by increased [Ca] plasma

T3, 4 negative feedback on HPA

Question 2

Hypothyroidism - most common cause
-associations
-presentation
-investigations
-management

Answer 2

Hashimoto’s thyroiditis - AI
-T1DM, pernicious anemia, Addisons

Transient thyrotoxicosis -> hypothyroidism

Hypothyroidism signs
Firm non-tender goitre

TPO AB

Levothyroxine - aim for normalisation of TSH
-test TFT after 8-12wks of dose change
ENSURE TO TAKE LEVO + Fe/Calcium carbonate 4HRS APART

SE
-hyperthyroidism - overtreatment
-reduced bone mineral density
-worsening angina
-AF

Question 3

Hyperthyroidism - most common cause
-associations
-presentation

Answer 3

Graves’ disease - AI

Hyperthyroidism signs +
Thyroid eye disease
-exopthalmos
-opthalmoplegia
Pretibial myxoedema
Thyroid acropachy
-digital clubbing
-soft tissue swelling of the hands and feet
-periosteal new bone formation

TSH AB
Diffuse, homogenous increased uptake of radioactive iodine

Initial symptom control - propanolol
2ndary care referral for ongoing treatment

Carbimazole 40mg, gradually reduced to maintain euthyroidism
If ATD fails - radioiodine treatment, unless pregnancy, U16, thyroid eye disease
-may need thyroxine supplementation after 5 years

Question 4

Subacute thyroiditis (De Quervian’s)
-pattern of presentation
-investigations
-management

Answer 4

Follows viral infection
Phase 1 (3-6wks) - hyper, painful goitre, high ESR
Phase 2 (1-3wks) - euthyroid
Phase 3 (wks-months) - hypo
Phase 4 - structure and function normal

Thyroid scintigraphy - globally reduced iodine uptake

Self limiting
NSAIDs - pain
If severe - CS

Question 5

Riedel thyroiditis
-pathophysiology
-presentation

Answer 5

Fibrous tissue replacing normal thyroid tissue

Hypo

Hard, fixed, painless goitre
Retroperitoneal fibrosis

Question 6

Postpartum thyroiditis

Answer 6

Brief hyper => longer hypo

Question 7

Causes of drug induced thyroiditis
-hyper or hypo

Answer 7

Lithium - hypo
Amiodarone - hypo and hyper

Question 8

Most common cause of hypothyroidism in the developing world

Answer 8

Iodine deficiency

Question 9

Toxic multinodular goitre
-presentation
-investigations
-management

Answer 9

Autonomously functioning thyroid nodules => secrete excess thryoid hormone

Hyper

Nuclear scintigraphy - patchy uptake

Radioiodine therapy

Question 10

Features of hypothyroidism

Answer 10

Weight gain
Lethargy
Constipation
Cold intolerance
Dry skin
Bradycardia, arrythmia
Non pitting edema
Decreased reflexes
Carpal tunnel
Dry coarse hair, loss of 1/3d of eyebrow
Menorrhagia

Question 11

Features of hyperthyroidism

Answer 11

Weight gain
Manic, restless, anxiety, tremor
Diarrhoea
Heat intolerance
Sweating
Tachycardia, palpitations, arrythmias
Oligomenorrhea

Question 12

Investigations and diagnosis for thyroid issues
-thyrotoxicosis
-primary hypo
-secondary hypo
-sick euthyroid
-subclinical hypo
-poor compliance
-ABs

Answer 12

TFT
Thyrotoxicosis
-TSH low
-T4 high

Primary hypo
-TSH high
-T4 low

Secondary hypo
-TSH low
-T4 low

Sick euthyroid - common in hospital IP
-TSH low
-T4 low

Subclinical hypothyroidism
-TSH high - more sensitive for early thyroid problems
-T4 normal

Poor compliance with T4
-TSH high - measure of long term control
-T4 normal

TPO AB - Hashimoto
TSH AB - Graves

Question 13

Management of thyrotoxicosis

Answer 13

Acute symptom management - propanolol

Carbimazole => reduce thyroid hormone production
-watch out for agranulocytosis

Question 14

Thyroid eye disease
-what is it
-presentation
-management

Answer 14

AI response against TSH receptor => retroorbital inflammation

Can be eu/hypo/hyperthyroid
Exopthalmos
Conjunctical edema
Optic disc swelling => optic neuropathy
Opthalmoplegia => strabismus, diplopia
Cannot close eye => exposure keratopathy

Smoking cessation
Eye lubrication
Steroids
RT
Surgery

Question 15

Thyroid nodules
-benign and malignant causes
-investigations
-management if malignant

Answer 15

Benign
-multinodular goitre
-thyroid adenoma
-Hashimotos
-cysts

Malignant
-papillary - most common but best prognosis
-follicular
-medullary - part of MEN2
-anaplastic - worst prognosis
-lymphoma - linked to Hashimotos

TFT
US - identify malignant features

Total thyroidectomy
Radioiodine to kill residual cells
Yearly thyroglobulin to detect early recurrent disease

Question 16

Thyroid storm
-what is it
-triggers
-presentation
-management

Answer 16

Endocrine emergency in established thyrotoxicosis

Surgery
Trauma
Infection
Acute iodine load (CT contrast media)

High fever, HR, HTN
Confusion, agitation
N/V
Heart failure
Abnormal LFTs

Symptomatic treatment
Treat trigger
Bb - IV propanolol
Anti-thyroid meds - methimazole/propylthiouracil
Lugol’s iodine
Dexmeth

Question 17

Subclinical hypothyroidism
-investigation findings
-management and when to treat

Answer 17

TSH high
T3, T4 normal
No obvious symptoms

Asymptomatic => repeat in 6 months

TSH 10+ on 2 separate occasions, 3 months apart => levothyroxine

TSH 5.5 - 10 on 2 separate occasions, 3 months apart + symptomatic => 6 months levothyroxine if U65

If 65+ => watch and wait

Question 18

Subclinical hyperthyroidism
-investigation findings
-associations
-management

Answer 18

TSH low
T3, T4 normal

Multinodular goitre
Excess T4
=> can lead to AF and osteoporosis

If TSH persistently low => low dose antithyroid meds 6 months to induce remission

Question 19

Sick euthyroid syndrome
-investigations findings
-management

Answer 19

T3, T4 - low
TSH - low, normal

Resolves on recovery of systemic illness => self limiting
-repeat TFTs in 6wks

Question 20

Myxodemic coma
-what is it
-presentation
-management

Answer 20

Hypothyroid endocrine emergency

Confusion
Hypothermia

IV thyroid replacement
IV fluid
IV CS - until coexisting adrenal insufficiency excluded
Electrolyte imbalance correction
Rewarming