5% women

1% men

lack of evidence to support routine screening in asymptomatic people

TSH = initial test

Hypothyroidism

suspicion

• high

  • goitre

  • delayed reflexes

• intermediate

  • fatigue

  • weight gain/difficulty losing weight

  • cold intolerance

  • dry, rough, pale skin

  • consitpation

  • facial swelling (oedema)

  • hoarseness

• Low

  • coarse dry hair

  • hair loss

  • muscle cramps/aches

  • depression

  • irritability

  • memory loss

  • abnormal menstrual cycles

  • decreased libido

risk factors

• autoimmune disease

  • t1 DM

  • addison’s disease

  • coeliac disease

• genetic conditions

  • Down

  • Turner

• treatment with radioactive iodine therapy or surgery for hyperthyroidism

• radiotherapy to neck

• history of post partum thyroiditis

consider screening every 1-2 years or if symtoms/signs

Thyroid antibodies

• TPO-Ab

  • anti-thyroglobulin antibodies

  • risk factor for autoimmune throid disorders

  • all with autoimmune hypothyroidism and up to 80% Graves disease have TPO antibodies

    • usually at high levels

Primary hypothyroidism

• increased TSH and decreased FT4

  • untreated

    • fatigue

    • weight gain

    • abnormal lipid profile

    • heart failure

    • children: retard growth and mental development

    • myxodedema coma = rare complication

  • autoimmune thyroid disease: Hashimoto’s throiditis/atrophic thyroiditis

  • consider iodine deficiency

Treatment

• Replacement for symptomatic with TSH >10

  • lower threshold to treat young woman especially if may become pregnant

  • 2nd TSH to confirm diagnosis

• Levothyroxine

  • 1.6mck.kg.day

  • young adults start full dose

  • elderly start 12.5-25mcg/day and inc every 6 weeks

    • long term bradycardia may mask coronary artery disease

  • symptoms generally improve within 2–3 weeks

  • months before patient feels bakc to N health after biochemical correction of TSH

  • Once target reached - furtehr TSH in 3-4mo

  • annual TSH once stable

    • unless pregnant

  • if dose change

    • 6-8wks

  • active ingredient same across all brands but absorption may be different

    • if switch brand - repeat 6 weeks

  • calcium, iron, aluminum hydroxide (antacids) and cholestyramine reduce absoprtion of levothyroine

    • take 4 hours apart

  • max absorption - take on empty stomach before breakfast

  • long half life = 7d

  • anticonvulsants and oestrogen therapy

    • increase levothyroxine requirments

  • TSH  = most appropriate test for monitoring hypothyroidism

Referal

• TSH persistently above normal range

  • check compliance

  • drug interactions

  • coeliac disease

• symptoms don’t respond or woresen after treatment

• pregnant/postpartum

• children \<16yo

• patients with co-morbidities

  • unstable ischaemic heart disease

Subclinical hypothyroidism

• increase TSH

• noraml FT4

• may develp hypothyroidism

Treatment

• TSH \<10

  • may be considered if symptoms

  • or rising TSH or those who have goitre

  • treat for 3mo to assess symptomatic benefit

  • if not treated then monitor q6-12mo or if symptoms

• autoimmune Hashimoto’s thyroiditis = common cause

  • if TSH >7 and antiTPO + then consider treatment

• persistently >10

  • consider treatment

Hyperthyroidism

suspicion

• high

  • goitre

  • thyroid bruit

  • lid lag

  • proptosis

• intermediate

  • fatigue

  • weight loss

  • heat intolerance/sweating

  • fine tremor

  • increase bowel movements

  • fast heart rate/palpitaitons

  • staring gaze

• low

  • nervousness

  • insomnia

  • breathlessness

  • light/absent menstrual periods

  • muscle weakness

  • warm moist skin

  • hair loss

Overt hyperthryoidism

• decrease TSH

• fT4 and /or FT3 above normal range

• complications

  • graves’ opthalmopathy

  • thyrotoxic crisis

  • AF

  • loss of bone mass

  • CHF

• causes:

  • Graves’ disease

    • 20-40yo

  • toxic nodular goitre

    • prevalence increase with age

  • Thyroiditis

    • post partum women

    • viral - type symptoms + neck pain

      • subacute thyroiditis

Treatment

• Carbimazole (thionamide)

  • first episode of Graves’

  • not indicated for thyroiditis where no excessive production of thyroid hormone

  • decrease thyroid hormone synthesis

    • interferes with organification of iodine (oxidation and binding)

  • can be started in primary care

  • 15-40mg od until euthyroid

    • 4-8wks

  • maintence = 5-15mg

  • block and replace used where high doses are used in combination with levothyroxine

  • prolonged use for 12-18mo provides best chance of sustained remission

  • relapse approx 50%

    • smokers

    • large goitres

    • suppressed TSH at end of therapy

  • monitoring

    • TSH q4wks using FT4 and TSH until TSH normal then q2mo

  • Adverse effects

    • rash, fever, GI 5%

    • Bone marrow suppression = agranulocytosis = 0.1-0.5%

      • stop and see doctor if fever, sore throat, other infections

        • urgent FBC

          • neutropenia

      • routine monitoring not recommended

      • affix to label:

        • ”report fever, sore throat or infection to doctor

• Betablockers

  • propranolol

  • rapid relief of adrenergic symptoms

    • tachycarida

    • tremor

    • heat intolerance

    • anxiety

• radioactive iodine/surgery

  • relapses

  • may be appropriate first choice treatment for toxic nodular goitre

Subclincial hyperthroidism

• TSH low

• FT4/3 normal

• causes

  • excessive levothyroxine replacement

  • autonomously functioning multi-nodular goitre

  • subclinical Graves’ disease

• increased risk of AF

  • possibly osteoporosis

• if undetectable TSH then consider treatment

Pregnancy

Hypothryoidism

• Screening not routinely recommeneded

  • subclinical hypothyroidism associatedwith ovulatory dysfucntion and infertility

• Thryoid testing

  • symptoms

  • increase risk

    • T1DM

    • personal or FHx

• TSH temporarily decrease first trimester

  • Thyriod stimulating effects of hCG

  • FT4 tends to fall slowly in second half of pregnancy

• Aim

  • normalise both TSH and FT4

• majority need dose increase

  • usually during first 1/3

    • proactive increase 30% once pregnancy confirmed

      • double maintenece on 2 days/week

    • Dose requirement stabilise by 20weeks then fall back to normal

    • t4 above 10-14

Hyperthyroidism

• increase risk of foetal loss, pre-eclampsia, heart failure, premature labour, low birth-weight infant

• Thionamides preferred treatment choice

• lowest possible dose to control symptoms

• last trimester cease anti-thryoid

• propylthiouracil (PTU) preferred

  • carbimazole associated with rare teratogenic effects

  • associated significant liver toxicity

  • block and replace not suitable

drugs

Amiodarone

• either hypo/hyper 14-18%

  • high iodine content

  • direct toxic effect on thyroid

• initial rise in TSH will return to nroaml within 3mo

• inbhibits peripheral conversion of T4-T3

• TSH best marker

• baseline then 6 monthly

• monitoring 12mo after cesastion may be required

Lithium

• hypothyroidism common

• appear abruptly even after long-term treatment

• Femalses and people with + TPO antibodies are at increase risk

• Lithium-associated hyperthyroidism rare

• TSH and FT4 @ baseline

• TSH @ 3 months

• then yearly