Thyroid - Hashimoto, Graves, Subacute, Riedel, Postpartum, Drug-induced, Toxic multinodular goitre, Thyroid storm, Myxedemic coma, Subclinical Flashcards
Structure and function of thyroid gland
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
Hypothyroidism - most common cause
-associations
-presentation
-investigations
-management
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
Hyperthyroidism - most common cause
-associations
-presentation
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
Subacute thyroiditis (De Quervian’s)
-pattern of presentation
-investigations
-management
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
Riedel thyroiditis
-pathophysiology
-presentation
Fibrous tissue replacing normal thyroid tissue
Hypo
Hard, fixed, painless goitre
Retroperitoneal fibrosis
Postpartum thyroiditis
Brief hyper => longer hypo
Causes of drug induced thyroiditis
-hyper or hypo
Lithium - hypo
Amiodarone - hypo and hyper
Most common cause of hypothyroidism in the developing world
Iodine deficiency
Toxic multinodular goitre
-presentation
-investigations
-management
Autonomously functioning thyroid nodules => secrete excess thryoid hormone
Hyper
Nuclear scintigraphy - patchy uptake
Radioiodine therapy
Features of hypothyroidism
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
Features of hyperthyroidism
Weight gain
Manic, restless, anxiety, tremor
Diarrhoea
Heat intolerance
Sweating
Tachycardia, palpitations, arrythmias
Oligomenorrhea
Investigations and diagnosis for thyroid issues
-thyrotoxicosis
-primary hypo
-secondary hypo
-sick euthyroid
-subclinical hypo
-poor compliance
-ABs
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
Management of thyrotoxicosis
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
Thyroid eye disease
-what is it
-presentation
-management
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
Thyroid nodules
-benign and malignant causes
-investigations
-management if malignant
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
