Enlargement of thyroid gland Patients may be - hyperthyroid - euthyroid - hypothyroid

Thyroid disease: hyper, hypo and other Flashcards by Holly O'Flanagan

Hypothyroidism

Underproduction of thyroid hormone

Primary- due to a thyroid problem

Secondary- due to a hypothalamic/ pituitary problem

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Hyperthyroidism

Thyrotoxicosis

Overproduction of thyroid hormone

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Euthyroid

Normal production o f thyroid homrone

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Goitre

Enlargement of thyroid gland

Patients may be

hyperthyroid
euthyroid
hypothyroid

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Examining the thyroid

Low down in the neck

Feel for thyroid cartilage then down and laterally

Moves on swallowing

Listen for a bruit

Retrosternal extension

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Normal range thyroid function tests

TSH: 0.3-4.2 mu/l

FT4: 12-22 pmol/l

FT3: 3.1-6.8 pmol/l

Thyroid antibodies

anti-TOP AB (thyroid peroxidase auto antibody)
TRAB (TSH receptor auto antibody)

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TSH

The best biomarker of thyroid status

Slow to respond to change (about 6 weeks)

Assumes normal pituitary function

Remember the negative feedback regulation

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Thyroid autoantibodies

Prevalence of autoAB > autoimmune disease
- marker of risk, or causal

Negative autoAB result does not exclude autoimmune disease; presence heps confirm diagnosis

Different types of thyroid autoantibodies

destructive- target thyroid for autoimmune destruction
stimulatory- stimulate TSH receptor

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Symptoms of hypothyroidism

May be none

Lethargy

Mild weight gain

Cold intolerance

Constipation

Facial puffiness

Dry skin

Hair loss

Hoarseness

Heavy menstrual periods

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Signs of serve hypothyroidism

Change in appearance e.g. face puffy and pale

Perioribital oedema

Dry flaking skin

Diffuse hair loss

Bradycardia

Sings of median nerve compression (carpal tunnel)

Effusions e.g. ascites, pericardial

Delayed relaxation of reflexes

Croaky voice

Goitre

Rarely stupor or coma

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Causes of primary hypothyroidism

Autoimmune hypothyroidism

Hypothyroidism after treatment for hyperthyroidism

Thyroiditis

Drugs (e.g. lithium, amiodarone)

Congenital hypothyroidism

Iodine deficiency

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Causes of secondary hypothyroidism

Diseases of the hypothalamus or pituitary

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Treatment for hypothyroidism

Start with thyroxine (T4) 100ug daily

shorter symptomatic period
unless elderly/ ischaemic heart disease

Usual dose 100-150ug daily
- some variation with body weight

Aim normal FT4 without TSH suppression
- individual variation: may need fine tuning within reference ranges

No evidence in properly conducted trials to support T4/T3 combination

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Chronic autoimmune thyroiditis

Hasimoto’s disease

With a goitre

With a lymphocytic infiltration

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Myxoedema (coma)

Accumulation of glycosaminoglycans in interstitial spaces of tissues

Very severe hypothyroidism

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Symptoms of thyrotoxicosis

Weight loss

Lack of energy

Heat intolerance

Anxiety/ irritability

Increased sweating

Increased appetite

Thirst

Palpitations

Pruritus

Weight gain

Loose bowel

Oligomenorrhoea

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Signs of thyrotoxicosis

Tremor

Warm, moist skin

Tachycardia

Brisk reflexes

Eye signs

Thyroid bruit

Muscle weakness

Atrial fibrillation

Mild symptoms of thyroid eye disease/ thyroid associated opthalmopathy

Itchy/ dry eyes

Prominent eyes/ change in appearance

Worrisome symptoms of TED/ TAO

Diplopia/ loss of sight

Loss of colour vision

Redness/ swelling of conjunctiva

Unable to close eyes fully

Ache/ pain/ tightness in or behind eye

Signs associated with thyrotoxicosis

Hands

fine tremor
warm

Pulse

sinus tachycardia
atrial fibrillation

Neck

goitre
move when swallow
smooth/ not
bruit/ not

Eyes

lid retraction/ lid lag
proptosis/ exophthalmos
opthalmoplegia
inflammation

Causes of thyrotoxicosis

Graves disease

Autoantibody stimulates the TSH receptor

Causes excess thyroid hormone production and thyroid growth

Other causes of thyrotoxicosis

Toxic multinodular goitre

Toxic adenoma

Thyroiditis

Drugs (e.g. amiodarone)

Gestational thyrotoxicosis

Placental B-human chorionic gonadotrophin is structurally similar to TSH and TSH like action on the thyroid

Increased likeliness if hyperemesis/ twin pregnancy

Settles after 1st trimester of pregnancy

Likely Graves disease if

Personal or family history of any autoimmune thyroid/ endocrine disease

Goitre with a bruit = graves disease

Thyroid eye disease = graves disease (20%)

Positive thyroid autoantibody titre

Graves disease treatment options

Medical Radioiodine Surgery Symptom control - beta blockers Risks of no treatment - symptoms worsening - atrial fibrillation - osteoporosis

Medical therapy of Graves disease

Carbimazole of propylthiouracil 18 months - 2 years Titrate or block replace Rare side effect: agranulocytosis Approx 1/3 long term cure rate 2/3 relapse - usually first year

Radioiodine

Oral treatment, radioiodine concentrated in thyroid, radiation kills thyroid cells Medical therapy first till euthyroid Not if pregnant. breast feeding Need to acoid prolonged close contact with other for 1-2 weeks after Not if severe thyroid eye disease

Surgery

Sub-total thyroidectomy Patients must be euthyroid pre-operatively Risks - anaesthetic - neck scar - hypothyroidism - hypoparathyroidism - coval cord palsy

Treatment for a toxic adenoma or toxic multinodular goitre

Initial treatment: short term medical therapy Subsequent curative treatment: radioiodine

Thyroid eye disease treatment options

Active - encourage smoking cessation - steroid - other immunosuppressive/ steroid sparing agents - radiotherapy Burn out - may be left with disfigurement causing impaired quality of life - surgical treatment (orbital decompression, eyelid surgery)

Thyroid storm

Thyrotoxic crisis

Who gets thyroid storm?

Usually secondary graves Unrecognised Incompletely treated - start- stop - erratic compliance - early on in course of treatment - surgery/ radioiodine treatment without adequate preparation

What triggers thyroid storm?

Surgery Childbirth Acute severe illness - infection - trauma - diabetic ketoacidosis - stroke - pulmonary embolus

What are the features of thyroid storm?

Multi-system Graves (goitre, TED) Hyperpyrexia CNS (agitation, delirium) CV (tachycardia, atrial dysrhythmias, ventricular dysfunction, heart failure) GI (nausea and vomiting, diarrhoea, hepatocellular dysfunction)

Thyroiditis

Transient mild thyrotoxicosis - always resolves - beta blockers if required - isotope scan would be cold - anti thyroid drugs will not work Longer hypothyroid phase - 80% normal at 1 year - may require thyoxine treatments for a while

Consider thyroiditis if

Patient is pregnant/ within 1 year post partum Patient has very tender thyroid Clinical thyroid status does not fit with lab results No diagnostic features of Graves disease Current/ recent treatment with immunomodulatory medication

Associations of autoimmune thyroid disease with other autoimmune endocrine diseases

Type 1 diabetes Pernicious anaemia Coeliac disease Premature ovarian failure Addison's disease

Association of autoimmune thyroid disease with syndromes

Turner syndrome Down's syndrome

Association of autoimmune thyroid disease with medication for other diseases

Lithium - inhibits thyroid hormone synthesis and secretion Amiodarone

Euthyroid goitre

Common More common in iodine deficient areas May be multinodular Usually nothing to worry about

Thyroid nodule

Must exclude thyroid cancer Ultrasound scan characteristics helpful Fine needle aspiration biopsy for cytology