Dr Andrew S Bates Heart of England Foundation Trust Thyroid Disease Dr Andrew S Bates Heart of England Foundation Trust

Outline What and where is it? What does it do? How is it controlled? What can go wrong with it? Functional disorders Hyper- and Hypothyroidism Goitre, nodules and tumours

The normal thyroid

What does the thyroid do? Secretes thyroid hormones (T4 and T3) Control basal metabolic rate Burn fat Increase heart rate Increase bone turnover

Thyroid Physiology Heavily dependent on iodine Iodination of thyroglobulin resulting in formation of mono- and di-iodotyrosines Iodotyrosines combine to form T4 (100%) and T3 (20%) - released into circulation 80% of T3 is formed outside the thyroid Deiodinases play important role in thyroid metabolism

How is it controlled?

What do we measure? TSH-most important FT4 and FT3 Thyroid antibodies Low or ‘turned off’ if overactive High if underactive FT4 and FT3 Occasionally useful in addition to TSH Thyroid antibodies Non-diagnostic but useful as a pointer to autoimmune thyroid disease

What can go wrong? Overactive Underactive Thyroid growths High free T4 low or suppressed TSH Underactive Low free T4 and high TSH Thyroid growths Goitre, nodules, cancer

Overactive thyroid

Thyroid Hormone Excess Clinical Features General Heat intolerance, fatigue, tremor. Cardiovascular Tachycardia, heart failure. Gastrointestinal Weight loss, diarrhoea Ophthalmological Lid lag, ophthalmopathy

Thyroid Hormone Excess Clinical Features Genitourinary Amenorrhea, infertility. Neuromuscular Proximal muscle weakness, HPP, MG Psychiatric Irritability, agitation, anxiety, psychosis Dermatological Pruritus, hair thinning, onycholysis, vitiligo.

Causes of Thyroid Hormone Excess Increased iodine uptake Graves Toxic Multinodular Goitre Toxic solitary adenoma

Causes of Thyroid Hormone Excess Reduced iodine uptake Thyroiditis Iodine induced (Amiodarone) Factitious

Increased iodine uptake

Selective iodine uptake

No iodine uptake

Graves Disease Most common cause in UK Diffuse Goitre Hyperthyroidism Ophthalmopathy Dermopathy Autoimmune.

Toxic Multinodular Goitre Older Usually less severe hyperthyroidism May have subclinical hyperthyroidism(normal thyroid hormones, low TSH) May have long history of goitre

Toxic Solitary Adenoma Rare cause (< 2% of patients with hyperthyroidism) Younger people 30’s and 40’s Isotope scan useful Benign follicular adenomas

Thyroiditis Painful (subacute, de Quervain’s) Painless (post partum) Hyperthyroid, hypothyroid and euthyroid phases Anti thyroid drug therapy does not work

Treatment of hyperthyroidism Antithyroid drugs Carbimazole 10 mg tid Reduce to maintenance after 4 weeks Rash, GI, agranulocytosis Graves – withdraw drugs after course of treatment

Treatment of hyperthyroidism Radio-iodine Inflammatory response followed by fibrosis May be used for Graves, TMG or TA ? Need for drug treatment before and after May need retreatment Long term risk of hypothyroidism

Treatment of Hyperthyroidism Surgery Rarely used nowadays Need to be rendered euthyroid before surgery Lugol’s iodine 0.1-0.3 mls tid for 10 days before surgery

Graves Eye Disease Onset relative to hyperthyroidism is variable. Pain, watering, photophobia, blurred vision, double vision Usually mild – Tx, protective glasses, elevate head of bed, conjunctival lubricants

Graves Eye Disease High dose steroids External radiotherapy Orbital decompression

Thyroid Eye Disease

Hypothyroidism Autoimmune Hashimoto’s Iatrogenic Congenital Hypopituitarism

Treatment Thyroxine – variable doses. Aim to normalize TSH In patients with heart disease start with lower dose e.g. 25ug once daily.

Multinodular Goitre

Simple non-toxic goitre Normal TFT’s No treatment required Surgery if obstructive symptoms

Nodular Thyroid Disease Prevalence 5-50% Depending on age and methods used Clinically apparent nodules in 4-7% UK population Four times more common in women <5% are cancerous

Nodular Goitres Factors Favouring Benign Factors Favouring Benign Disease Age Family history of benign thyroid nodule Presence of hyperthyroidism Associated pain or tenderness Soft, smooth, mobile nodule Multinodular goitre without a dominant nodule

Nodular Goitres Factors Favouring Benign Management Clinical history and examination Thyroid function tests Ultrasound Fine Needle Aspiration Surgery

Conclusion A small but very important gland with many vital functions Commonly develops faults, but fortunately most are easily sorted out