Thyroid disorders PDF

Preview

Summary

**Thyroid disorders **- Around 2% of the UK population have hypothyroidism and 1% have thyrotoxicosis- Both are around 10 times more common in women than menStructure and function: -- One of the largest endocrine organs in the body- Bi-lobes and found in the anterior neckPart of a hypothalamus pitui...

Description

Thyroid(disorders(

- Around(2%(of(the(UK(population(have(hypothyroidism(and(1%(have(thyrotoxicosis(( - Both(are(around(10(times(more(common(in(women(than(men(( Structure(and(function:(( - One(of(the(largest(endocrine(organs(in(the(body(( - Bi-lobes(and(found(in(the(anterior(neck(( - Part(of(a(hypothalamus(pituitary(end-organ(system(with(negative(feedback(cycles(to(maintain( normal(circulating(levels(of(the(hormone(thyroxine(and(triiodothyronine( - Hypothalamus(secretes(TRH((thyrotropin(releasing(hormone),(which(stimulate(the(anterior( pituitary(to(secrete(TSH((thyroid-stimulating(hormone)(( - This(acts(on(the(thyroid(increasing(the(production(of(thyroxine((T4)(and(triiodothyronine((T3)( - These(then(act(on(a(variety(of(tissues,(helping(to(regulate(the(use(of(energy(sources,(protein( synthesis,(and(controls(the(body’s(sensitivity(to(other(hormones(( Classification:(( Hypothyroidism:( - Primary(—>(there(is(a(problem(with(the(thyroid(gland(itself,(e.g.(autoimmune(disorder(affecting( thyroid(tissue(( - Secondary(—>(usually(due(to(disorder(of(the(pituitary(gland((e.g.(pituitary(apoplexy)(or(a(lesion( compressing(the(pituitary(( - Congenital(—>(due(to(a(problem(with(thyroid(dysgenesis(or(thyroid(gyshormonogenesis(( Whilst(there(are(a(number(of(causes(of(thyroxicosis,(the(vast(majority(are(primary(in(nature.( Congenital(thyrotoxicosis(is(not(seen(and(secondary(hyperthyroidism(is(rare,(account(for(less(than( 1%(of(cases.((

What(causes(thyroid(problems?(( - Usually(a(consequence(of(autoimmunity(( Hypothyroidism:(( Hashimoto’s(thyroiditis:( - Most(common(cause(in(developed(world(( - Autoimmune(disease,(associated(with(T1D,(Addison’s(or(pernicious(anaemia(( - May(cause(transient(thyrotoxicosis(in(the(acute(phase(( - 5-10(times(more(common(in(women(( Subacute(thyroiditis((de(Quervain’s):( - Associated(with(a(painful(goat(and(raised(ESR( Riedel(thyroiditis:( - Fibrous(tissue(replacing(the(normal(thyroid(parenchyma(( - Causes(painless(goitre( Drugs:(( - Lithium( - Amiodarone(( Iron(deficiency:((

- Most(common(cause(of(hypothyroidism(in(developing(world(( Also(—>(postpartum(thyroiditis(( Hyperthyroidism:( Grave's(disease:( - Most(common(cause(of(thyrotoxicosis(( - As(well(as(typical(features(of(thyrotoxicosis,(other(features(may(be(seen(including(thyroid(eye( disease(( Toxic(multi-nodular(goitre:( - Autonomously(functioning(thyroid(nodules(that(secrete(excess(thyroid(hormones(( Drugs:(( -(Amiodarone(( Symptoms(and(signs:(( Hypothyroidism:(( - Weight(gain( - Lethargy(( - Cold(intolerance(( - Dry((anhydrosis)(skin,(cold,(yellowish(( - Non-pitting(oedema(e.g.(hands(and(face( - Dry,(coarse(scalp(hair,(loss(of(lateral(aspect(of(eyebrows(( - Constipation(( - Menorrhagia(( - Decreased(deep(tendon(reflexes( - Carpal(tunnel(syndrome(( Thyrotoxicosis:(( - Weight(loss(( - ‘Manic’,(restlessness( - Heat(intolerance(( - Palpitations,(may(even(provoke(arrhythmias(e.g.(AF(( - Increased(sweating( - Pretibial(myxoedema:(erythematous,(oedematous(lesions(above(lateral(malleoli(( - Thyroid(acropachy:(clubbing(( - Diarrhoea( - Oligomenorrhea( - Anxiety( - Tremor(( Investigations(and(diagnosis:( Note(that(TSH(levels(are(more(sensitive(than(T4(levels(for(monitoring(patients(with(existing( thyroid(problems(and(are(often(used(to(guide(treatment.( - Thyrotoxicosis(e.g.(Grave’s(—>(low(TSH,(high(T4( - Primary(hypothyroidism(e.g.(Hashimoto’s(—>(high(TSH,(low(T4( - Secondary(hypothyroidism(—>(low(TSH,(low(T4( - Sick(euthyroid(syndrome(—>(low(TSH,(low(T4(—>(common(in(hospital(inpatients,(changes(are( reversible(upon(recovery(from(systemic(illness(and(no(treatment(is(usually(needed(

- Subclinical(hypothyroidism(—>(high(TSH,(normal(T4(( - Poor(compliance(with(thyroxine(—>(high(TSH,(normal(T4(—>(may(only(take(it(before(routine( bloods(—>(thyroxine(hence(normal(but(TSH(lags(and(reflect(longer(term(low(thyroxine(levels(( Autoantibodies:( - Anti-TPO((anti-thyroid(peroxidase)(antibodies((in(90%(of(patients(with(Hashimoto’s)( - TSH(receptor(antibodies((present(in(90-100%(of(patients(with(Grave’s(disease)( - Thryoglobulin(antibodies(( Other(tests:(( - Nuclear(scintigraphy((thyroid(scan)(—>(toxic(multi-nodular(goitre(revels(a(patchy(uptake(( Treatment:( - For(hypothyroidism(—>(thyroxine(is(given(in(the(form(of(levothyroxine(to(replace(underlying( deficiency(( Thyrotoxicosis:(( - Propranolol(—>(controls(thyrotoxic(symptoms(e.g.(tremor(( - Carbimazole(—>(blocks(thyroid(peroxidase(from(coupling(and(ionidating(the(tyrosine(residues( on(thyroglobulin(—>(reducing(thyroid(hormone(production((be(aware(of(agranulocytosis)( - Radioiodine(treatment(...