4 main Thyroid function tests
TSH [most influential]
- Low= hyperthyroidism, secondary hypothyroidism
- High= Primary hypothyroidism
FT3
FT4
Thyroid auto-antibodies
Thyroid autoantibodies
Used to measure thyroid functioning.
Examples
- Anti-thyroid peroxidase
- TSH receptor antibody [TRAB]
TSH receptor antibodies
Antibodies directed against the TSH receptor
- Can stimulate or block the receptor
Amount is measured to assess function of the thyroid.
- Blocking TRAb= hypothyrodism, such as Hashimoto’s
- Stimulating TRAb= Graves’
Anti-thyroid peroxidase antibody
- Raise antibodies indicate…
Antibodies that target thyroid peroxidase
Thyroid peroxidase enzyme facilitates the addition of iodine into thyroglobulin.
Raised antibodies indicate
- Graves’ disease
- Hashimoto’s thyroiditis
- Nodular goitre
- Thyroid carcinoma
Causes of hyperthyroidism [6]
Autoimmune [Graves’ disease]
Toxic multinodular goitre
Thyroiditis
Toxic adenoma
Pregnancy
Drugs [amiodarone]
Hyperthyroidism symptoms [9]
High temperature/ Heat intolerance
Increased appetite
Weight loss
Fatigue
Increased sweating, thirst
Diarrhoea
Oligomenorrhea
Agitation, irritability
Palpitations
Hair loss
Hyperthyroidism SIGNS
Tremors
Sweaty, moist skin
Goitre with bruit
Tachycardia, AF
Muscle weakness
Visual defects
Ophthalmoplegia [muscle paralysis around the eye]
Graves’ disease
- Presentation
- Cause
Presentation
- Most common cause of hyperthyroidism
- Mainly in women, 30-50 yrs
- Thyroid eye disease [20%]
- Goitre with bruit
- Family history of thyroid/ endocrine disease
Cause
- Autoimmune
- TSH receptors are overstimulated in the thyroid [high TSH-receptor antibody].
Investigating Graves’ disease
Prevalence of thyroid autoantibodies.
Thyroid uptake scan will show diffuse distribution.
Thyroid function results
- Low TSH
- High FT4, FT3
Graves’ disease medical treatment
- Duration
- Dosage
- Prognosis
18mons- 2yrs
- Carbimazole
- Propylthiouracil
Dosage can start high then get titrated down.
or
Block-replace
- High dose maintained whilst administering thyroxine.
Prognosis
- 1/3 cured
- The rest relapse
Radioioidine
- Indication
- Administration
- Risks
Radioactive iodine
- Used to treat hyperthyroidism
- Kills thyroid cells
Administered orally
Risk
- Hypothyroidism
- Close contact with others
- Contraindicated in thyroid eye disease
- Pregnancy [4-6 months wait at least]
- Airport security
Sub-total thyroidectomy
- Description
- Risks
Surgery that partial removes the thyroid
- Treats hyperthyroidism [Graves]
Requires medical therapy
- Must be euthyroid before surgery
Risks
- Anaesthetics
- Neck scar
- Hypothyroidism [thyroid hormones given life-long]
- Hypoparathyroidism
- Vocal cord palsy.
Gestational hyperthyroidism
Placental beta-human chorionic gonadotrophin [hCG] is released in the first trimester.
- hCG has similiar structure to TSH
- Reduces TSH levels and stimulates thyroid hormone productions
Hyperthyroidism risk increases when
- Pregnant with twins
- Has severe hyperemesis
Thyroid eye disease
- Description
Autoimmune condition that targets orbital tissue around the eyes
- Especially extra-ocular muscles.
Mainly associated with Graves’ disease
- Confirmatory feature.
Thyroid eye disease
- Presentation [7]
Proptosis
- Protrusion of the eyes
- Can cause inability to close eyes and lead to ulcerated corneas
Itchy/ dry eyes
Compression of the optic nerve can lead to colour blindness
Inflammation of the conjuctiva
Eyelid retraction
Periorbital oedema
Diplopia
Thyroid eye disease treatment [5]
Smoking cessation
Steroids
- IV methylprednisolone
- Oral prednisolone
Immunosuppressants
Radiotherapy
Surgery
- Relieve compression
Toxic adenoma
- Description
- Euthyroidism
- Treatment
Benign tumour of the thyroid that can secrete excess T3
- Causing hyperthyroidism
If euthyroid
- Cancer must be excluded
- Fine needle-aspiration biopsy
Treatment
- Short term medical initially
- Radioiodine
Euthyroid goitre
Enlargement of thyroid due to iodine deficiency.
Thyroid enlarges to absorb more iodine.
Toxic multi-nodular goitre
- Presentation
- Investigation
- Treatment
Presence of multiple adenomas on the thyroid.
- Nodules can secrete excess thyroid hormones causing hyperthyroidism
Investigation will show thyroid uptake scan with patchy appearance.
- Uptake more [darker] in nodules.
Treatment
- Initially medically, to control symptoms [beta-blockers]
- Curative= radioiodine.
Thyroid storm
- Description
- Causes
- Symptoms
- Treatment
A life-threatening increase in thyroid hormone effects.
Causes:
- Incomplete hyperthyroidism treatment.
- Untreated hyperthyroidism
Features:
- High fever
- Arrhythmia, tachycardia
- Vomiting, diarrhoea
Treatment
- Ionorganic iodine
- Anti-thyroid drugs [carbimazole, propylthiouracil]
- Beta blockers
- IV fluids
Triggers of thyroid storm [7]
Acute/ severe illness/ infection
Hypoglycaemia
Childbirth
Burns
MI, PE
Surgery
Diabetic ketoacidosis
Conditions associated with thyroid disease
- Autoimmune [5]
- Syndromes
- Drugs
Other autoimmune conditions
- T1 diabetes
- Pernicious anaemia
- Addison’s disease [hypoadrenalism]
- Premature ovarian failure
- Coeliac disease
Syndromes
- Turner’s
- Down’s
Drugs
- Lithium
- Amiodarone
Hypothyroidism
- Symptoms [8]
Lethargy
Weight gain [despite no change in diet and physical activity]
Cold intolerance
Constipation
Dry skin
Heavy periods
Hair loss
Puffy face
Hypothyroidism
- Signs [8]
Periorbital oedema
Flaking skin
Diffuse hair loss
Goitre
Carpel tunnel [compression of the median nerve]
Delayed reflex
Bradycardia
Effusions [severe]
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Introduction26
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The hypothalamic-pituitary axis18
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Anatomy30
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Calcium homeostasis22
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Adrenal causes of Hypertension17
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Adrenal cortex: Hormones, physiology23
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Histology of the endocrine system22
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Thyroid hormones and physiology28
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Thyroid diseases31
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Thirst and fluid balance26
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HPAA clinical aspects18
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Physiology of appetite and weight36
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T2 DM15
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T2 DM drugs32
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Endocrinology of ageing27
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Lactation, galactorrhoea, prolactinoma18
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T1 DM20
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T1 DM chronic consequences15
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T1 DM acute consequences14
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Male hypogonadism30
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Hormonal drug delivery28
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Pharmacology revision20
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Pituitary6
