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

1
Q

Structure and function of thyroid gland

A

Under thyroid and cricoid cartilage
Wraps around trachea

R, P, L lobe

TRH => TSH => T3 =(TPO)=> 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

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2
Q

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

A

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

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3
Q

Hyperthyroidism - most common cause
-associations
-presentation

A

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

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4
Q

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

A

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

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5
Q

Riedel thyroiditis
-pathophysiology
-presentation

A

Fibrous tissue replacing normal thyroid tissue

Hypo

Hard, fixed, painless goitre
Retroperitoneal fibrosis

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6
Q

Postpartum thyroiditis

A

Brief hyper => longer hypo

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7
Q

Causes of drug induced thyroiditis
-hyper or hypo

A

Lithium - hypo
Amiodarone - hypo and hyper

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8
Q

Most common cause of hypothyroidism in the developing world

A

Iodine deficiency

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9
Q

Toxic multinodular goitre
-presentation
-investigations
-management

A

Autonomously functioning thyroid nodules => secrete excess thryoid hormone

Hyper

Nuclear scintigraphy - patchy uptake

Radioiodine therapy

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10
Q

Features of hypothyroidism

A

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

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11
Q

Features of hyperthyroidism

A

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

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12
Q

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

A

Neck examination
-moves on swallowing?
-palpates for nodules
-auscultate bruits
-retrosternal extension

TFTs - TSH, T4, T3, ABs
US for nodules, cancer
Iodine uptake if ABs negative
MRI pituitary if suspecting 2ndary

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

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13
Q

Management of thyrotoxicosis

A

Acute symptom management - propanolol

Carbimazole - inhibits TPO action
-watch out for agranulocytosis
CI
-1st trimester

PTU - inhibits conversion of T4 => T3
-avoid in 3rd trimester due to maternal liver damage

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14
Q

Thyroid eye disease
-what is it
-presentation
-management

A

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

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15
Q

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

A

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

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16
Q

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

A

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

17
Q

Subclinical hypothyroidism
-investigation findings
-management and when to treat

A

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

18
Q

Subclinical hyperthyroidism
-investigation findings
-associations
-management

A

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

19
Q

Sick euthyroid syndrome
-investigations findings
-management

A

T3, T4 - low
TSH - low, normal

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

20
Q

Myxodemic coma
-what is it
-presentation
-management

A

Hypothyroid endocrine emergency

Confusion
Hypothermia

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