e-learning | Thyroid Disease

This is a new guideline from NICE, published in Nov 19, on thyroid disease.

Much of this guideline supports our current practice. There were a few new bits for me and I have listed these below, then summarised the guideline.

The guideline covers both children and adults, but as we mainly deal with adults with thyroid problems, I have not covered any of the details of how to manage or investigate children. Just be aware that the advice for kids is there if you need it.

What was new in this guideline for me:

  • Symptoms may lag behind treatment changes by weeks, or even months.
  • The body has a good reservoir of thyroxine, so symptoms that change day by day are unlikely to be due to thyroid disease.
  • Consider checking TFTs in children with altered behaviour or school performance.
  • Consider checking TFTs in women with menopausal symptoms if you feel it could be related to thyroid dysfunction. Many symptoms overlap.
  • Do not do TFTs if the only reason for doing them is that the patient has Type 2 Diabetes (T2DM). Evidence shows that there is no correlation between T2DM and thyroid dysfunction. This is obviously not the case for Type 1 Diabetes, where there is good correlation.
  • Treating hypothyroidism. For adults under 65 with no history of CVD, use a starting dose of levothyroxine of 1.6mcg/kg, rounded to the nearest 25mcg.
  • Monitoring. Once there are 2 TSH levels in the normal reference range, 3 months apart, then go to annual monitoring.
  • Subclinical hypothyroidism. If they have TSH > 10 on 2 occasions, 3m apart, then consider treating. If TSH  is < 10 but over 5 on 2 occasions, 3m apart and the patient is symptomatic and under 65, then consider treating. In the over 65s, they advise being more cautious, because side-effects from treating are more common (eg AF).
  • Subclinical hyperthyroidism. Consider seeking specialist advice for a child or young person. For an adult, consider seeking specialist advice if there are 2 TSH readings < 0.1, 3m apart and the patient is either symptomatic, or has goitre, or has positive thyroid antibodies.

What advice should we give to patients with thyroid disease?

Among the normal advice you would give, advise that:

  • Symptoms may lag behind treatment changes by weeks or months.
  • As the body has a good reservoir of thyroxine, day to day changes in symptoms are unlikely to be thyroid related.
  • Warn patients that some OTC medications can affect thyroid function.
  • Goitre. If patients have a goitre, warn them to watch out for SOB, rapid growth of nodules, a hoarse voice or swallowing difficulties.

When should we check TFTs?

Check TFTs if:

  • Symptoms of thyroid dysfunction.
  • Patients with T1DM, or other autoimmune disorders.
  • Patients with new AF.

Consider checking TFTs if:

  • Depression or anxiety.
  • Children with abnormal growth, unexplained changes in behaviour or school performance.
  • Women with menopausal symptoms.

Do not do TFTs if:

  • T2DM is the only reason for doing them (see above for the reasons why).
  • There is an acute illness (unless you suspect thyroid dysfunction to be the cause).

What tests should we be doing?

TSH alone (unless you suspect secondary thyroid disease).

  • If TSH is high, measure free T4 in the same sample.
  • If TSH is low, measure free T4 and free T3 in the same sample.

Consider measuring both TSH and free T4 initially if:

  • Secondary causes are suspected (eg pituitary).
  • Children and young people.

Consider repeating the tests if symptoms worsen, or if new symptoms develop, but don't repeat it within 6/52.

Definitions

  • Hypothyroidism. High TSH, low free T4.
  • Subclinical hypothyroidism. High TSH, normal free T4.
  • Hyperthyroidism. Low TSH, high free T4.
  • Subclinical hyperthyroidism. Low TSH, normal free T4.
  • Thyrotoxicosis. Symptoms caused by excess circulating thyroid hormones. This can be due to hyperthyroidism (eg excess production), or thyroiditis (eg excess release). 75% of cases are caused by Graves' disease.
  • Thyroiditis. Release of stored thyroid hormones due to destruction of the thyroid cells. Causes about 10% of thyrotoxicosis.

If like me your memory of the endocrinology and pathology of hyperthyroidism is a little hazy, then patient.co.uk has an excellent summary.

Managing primary hypothyroidism

Other tests indicated

In adults, check thyroid peroxidase antibodies (TPOAbs), if TSH is high. Do not repeat it.

Treatment

Use levothyroxine.

Do not routinely offer liothyronine or natural thyroid extract. There is not enough evidence of benefit over levothyroxine and the long term adverse effects are uncertain.

Doses

  • Under 65 with no evidence of coronary vascular disease (CVD). Consider starting at 1.6mcg/kg (rounded to the nearest 25mcg).
  • Over 65 or those with a history of CVD. Consider starting at 25 to 50mcg then titrating the dose up as appropriate.

Target

Aim to keep TSH in the reference range.

Adjust the dose as necessary, but avoid oversupression or thyrotoxicosis. Beware that the TSH can take 6 months after treatment to normalise if it has been very high, or suppressed for a long time.

Frequency of monitoring

Measure TSH until it is stable (ie 2 similar readings in the reference range at least 3m apart); recheck the level annually. If they have ongoing symptoms, consider measuring free T4.

Managing subclinical hypothyroidism

Other tests indicated

Consider measuring TPOAbs if TSH is above the reference range. Do not repeat them.

Treatment

When considering whether to treat people with subclinical hypothyroidism, take into account their symptoms, previous radioiodine treatment, previous thyroid surgery or raised levels of TPOAbs.

Consider starting levothyroxine if:

  • TSH is above 10, on 2 separate occasions, at least 3m apart.
  • TSH < 10, but above the reference range on 2 separate occasions, at least 3m apart AND
    •  Age < 65
    • They are symptomatic

If patients remain symptomatic and TSH is still raised, then adjust the dose of levothyroxine.

If patients remain symptomatic and TSH is in the reference range, then consider stopping levothyroxine and then monitoring as below.

It is worth noting that in 50% of patients with TSH 5 - 10, the TSH will return to normal. Older people are more likely to have side-effects from starting treatment (eg AF), which is why more caution is advised in this age group.

Monitoring untreated patients (eg with subclinical hypothyroidism or where treatment has been stopped.

Consider measuring TSH and free T4

  • Annually if there are features suggestive of underlying thyroid disease (eg raised TPOAbs or previous thyroid surgery).
  • 2-3 yearly otherwise.

If TSH and free T4 are similar and in the reference range on 2 tests, 3 months apart, then consider stopping monitoring if there are no features of underlying thyroid disease as above.

Managing Thyrotoxicosis

Further tests indicated

The aim is to try to distinguish between thyrotoxicosis with hyperthyroidism, and thyrotoxicosis without hyperthyroidism. Do:

  • TSH receptor antibodies (TRAbs) to confirm Graves' disease.
  • Consider using technetium scans (secondary care) if negative.
  • USS - consider this if there is a palpable nodule.

Initial management in primary care

The NICE guideline implies, though doesn't state, that all patients with thyrotoxicosis or hyperthyroidism need referring to secondary care.

  • Thyrotoxicosis without hyperthyroidism. Normally just needs supportive care (eg b-blockers).
  • Thyrotoxicosis with hyperthyroidism: consider anti-thyroid drugs alongside supportive care, whilst awaiting specialist care.

Drug options whilst awaiting secondary care

Check LFT and FBC before starting any medication.

Stop, and do not start, any new medication if the patient develops agranulocytosis.

Offer carbimazole to adults in either:

  • block and replace regime OR
  • titration regime.

NB - both regimes of carbimazole are widely used and effective. There are more relapses with titration, but maybe fewer cases of agranulocytosis. Block and replace regimes need fewer follow-up appointments.

Consider propylthiouracil for adults who:

  • are experiencing side-effects with carbimazole.
  • are pregnant or trying to get pregnant.
  • have a history of pancreatitis.

NB - carbimazole is more effective than proplythiouracil and has fewer side-effects. It does however have a greater risk of hypothyroidism.

Monitoring patients on or after treatment for hyperthyroidism

During drug treatment. Consider measuring TSH, free T4 and free T3 every 6/52 until TSH is in the reference range. Then measure them every 3m until drugs are stopped. There is no need to measure FBC or LFT again unless there is a clinical reason to do so.

After drug treatment. Once drugs have stopped, measure TSH within 8/52, then every 3m for a year, then annually.

After radioactive iodine treatment. Measure TSH every 6m.

After surgery. Measure TSH every 6m after hemithyroidectomy.

Managing subclinical hyperthyroidism

Consider seeking specialist advice if an adult has:

  • 2 TSH readings < 0.1 at least 3m apart AND
  • they have symptoms, a goitre or positive antibodies.

If patients remain untreated, consider monitoring TSH every 6m and if that is abnormal, then free T4 and free T3.

Consider stopping monitoring if the patient has 2 similar TSH readings in the reference range, 3m apart.

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