Podcast - The TFTs challenge: NICE guidance on thyroid disease

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This episode makes reference to guidelines produced by the "National Institute for Health and Care Excellence" in the UK, also referred to as "NICE". Please note that the content on this channel reflects my professional interpretation/summary of the guidance and that I am in no way affiliated with, employed by or funded/sponsored by NICE.

 

My name is Fernando Florido and I am a General Practitioner in the United Kingdom. In this episode, I go through the NICE guideline on Thyroid disease: assessment and management [NG145], always focusing on what is relevant in Primary Care only.

I am not giving medical advice; this episode is intended for health care professionals; it is only my summary and my interpretation of the guidelines and you must use your clinical judgement.  

 

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The resources consulted can be found here:

Thyroid disease: assessment and management -NICE guideline [NG145] can be found here:

●      https://www.nice.org.uk/guidance/NG145

 

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Transcript

If you are listening to this podcast on YouTube, for a better experience, switch to the video version. The link is in the top right corner of the video and in the episode description.

Hello and welcome, I’m Fernando, a GP in the UK. Today we are going to go through the NICE guideline on Thyroid disease, always focusing on what is relevant in Primary Care only.

Right, we are not going to waste any time so let’s jump into it.

We will check TFTs if there is:

●     a clinical suspicion of thyroid disease, bearing in mind that 1 symptom alone may not be indicative of thyroid disease

●     type 1 diabetes or other autoimmune diseases, (but we will not offer testing only because of type 2 diabetes).

●     new-onset AF

●     depression or unexplained anxiety

●     abnormal growth in children and young people, or with an unexplained change in behaviour or school performance.

●     And we will be aware that in menopausal women symptoms of thyroid dysfunction may be mistaken for menopause

We will not test for TFTs during an acute illness unless we suspect the acute illness is due to thyroid dysfunction, because it may affect the test results.

So, what tests do we do as initial screening when thyroid dysfunction is suspected?

This will depend on whether we suspect a primary cause, that is, a cause arising from the thyroid gland, or a secondary cause, that is, a cause arising from the pituitary gland. Although the path lab will have processes to decide what tests are included when we request TFTs, it is important for us to understand what tests results we should expect according to the clinical presentation.

So, we will always measure TSH. Then, if a primary cause is suspected in an adult:

●     if the TSH is high, that is, suggestive of hypothyroidism, we will need the free thyroxine (FT4) level

●     if the TSH is low, that is, suggestive of hyperthyroidism, we will need FT4 and free tri-iodothyronine (FT3)

However, if we suspect a secondary cause, that is, pituitary disease, or if we are testing a child or young person, we will need results for both TSH and FT4 and:

●     If the TSH is low, that is, suggestive of hyperthyroidism, we will need FT3

So, in summary, we test TSH and T4 in hypothyroidism but in hyperthyroidism we need to add FT3 too.

We can repeat these tests if symptoms worsen or new symptoms develop (but no sooner than 6 weeks from the most recent test).

We will also ask patients about their biotin intake because a high consumption of biotin from dietary supplements may lead to falsely high or low test results.

Looking at the management, and monitoring different rules may apply to children and young people and given that we are likely to be getting advice from the paediatricians , I will not cover them here. If a recommendation applies to children, I will mention it, but otherwise this episode will focus on adults unless otherwise specifically stated.

So, we are going to cover:

●     Primary hypothyroidism: which is caused by an insufficient hormone production by the thyroid gland. In this situation the TSH is high, and FT4 is low.

●     Subclinical Primary hypothyroidism: This can sometimes happen as a precursor of clinical hypothyroidism and it is when the TSH is high, but FT4 is normal.

●     Thyrotoxicosis or Primary hyperthyroidism: Thyrotoxicosis is when there is excess thyroid hormone leading to a low TSH and a high FT4 and / or FT3. This can be caused by:

○     Increased production and secretion, as in primary hyperthyroidism or by

○     The release of stored thyroid hormones, as it happens in thyroiditis.

●     Subclinical Primary hyperthyroidism: This can also sometimes happen as a precursor of hyperthyroidism and it is when TSH levels are low, but FT3 and FT4 are normal.

●     And we will also cover Thyroid enlargement with normal thyroid function, which is self explanatory

So let’s start with the management of primary hypothyroidism

So, for all people with confirmed primary hypothyroidism, that is, when we encounter a high TSH and a low FT4, we will:

Check thyroid peroxidase antibodies (TPOAbs)

But in adults, we will not repeat TPOAbs testing. If the antibody test is positive, it maybe worthwhile mentioning that NICE also recommends testing for coeliac disease in people with a diagnosis of autoimmune thyroid disease.

For the actual management, for both adults and children, we will:

Offer levothyroxine as first-line treatment and we will not routinely offer liothyronine or natural thyroid extract for primary hypothyroidism, either alone or in combination with levothyroxine, because there is not enough evidence that it offers benefits over levothyroxine monotherapy, and the long-term adverse effects are uncertain.

We will start levothyroxine at a dosage of 1.6 micrograms per kilogram of body weight per day (rounded to the nearest 25 micrograms) for adults under 65 with primary hypothyroidism and no history of cardiovascular disease.

However, if they are over 65 or with a history of cardiovascular disease, we will start levothyroxine at a dosage of 25 to 50 micrograms per day with titration

How should we follow-up and monitor primary hypothyroidism?

We will aim to maintain TSH levels within the reference range when treating with levothyroxine. If symptoms persist, we will adjust the dose to achieve optimal wellbeing, but we will avoid using doses that cause TSH suppression or thyrotoxicosis.

We also need to be aware that the TSH level can take up to 6 months to return to normal for people who had a very high TSH or a prolonged period of untreated hypothyroidism.

In terms of monitoring, we will need to measure TSH every 3 months until the level has stabilised (that is, until we have had 2 similar measurements within the reference range 3 months apart), and then once a year. But we will also check FT4 as well as TSH if they continue to have symptoms on levothyroxine.

Let’s now look at subclinical hypothyroidism

Once we have confirmed subclinical hypothyroidism, with a high TSH and normal FT4, we will also check TPOAbs.

In terms of the management, we will:

take into account features that might suggest underlying thyroid disease, such as, for example, symptoms of hypothyroidism, or raised levels of thyroid autoantibodies.

Consider levothyroxine if the TSH is 10 mlU/litre or higher on 2 separate occasions 3 months apart, monitoring as per in hypothyroidism

We will also consider a 6-month trial of levothyroxine for adults under 65 with subclinical hypothyroidism who have:

●     a high TSH but lower than 10 mlU/litre on 2 separate occasions 3 months apart, and

●     symptoms of hypothyroidism.

If symptoms do not improve after starting levothyroxine, we will recheck the TSH and if the level remains raised, we will adjust the dose. If symptoms persist when TSH is within the reference range, we will stop levothyroxine and continue monitoring.

So, how do we monitor untreated subclinical hypothyroidism and after stopping treatment?

For them, we will check TSH and FT4:

●     once a year if they have features suggesting underlying thyroid disease, such as previous thyroid surgery or raised levels of thyroid autoantibodies, or

●     once every 2 to 3 years if they have no features suggesting underlying thyroid disease.

Let’s now have a look at thyrotoxicosis

First, we will have confirmed the diagnosis with a low TSH and raised FT4 and / or FT3.

Then we will need to differentiate between thyrotoxicosis with hyperthyroidism (for example, Graves' disease or toxic nodular disease) and thyrotoxicosis without hyperthyroidism (for example, transient thyroiditis). We will do so by:

●     measuring TSH receptor antibodies (TRAbs) to confirm Graves' disease. and

●     considering technetium scanning of the thyroid gland if TRAbs are negative.

We will only consider ultrasound for thyrotoxicosis if they have a palpable thyroid nodule. In terms of treatment, we need to be aware that transient thyrotoxicosis without hyperthyroidism like in thyroiditis usually only needs supportive treatment (for example, beta-blockers).

Otherwise we can consider antithyroid drugs along with supportive treatment for adults with hyperthyroidism who are waiting for specialist assessment and further treatment, bearing in mind that the use of carbimazole is subject to MHRA advice on contraception (Drug Safety Update, February 2019) and risk of acute pancreatitis (Drug Safety Update, February 2019).

Before starting antithyroid drugs,we will check a full blood count and liver function tests.

Antithyroid drugs for hyperthyroidism secondary to a single or multiple toxic nodules, will normally be with a titration regimen of carbimazole.

However, we will consider propylthiouracil for adults:

●     who experience adverse reactions to carbimazole

●     who are pregnant or trying to become pregnant within the following 6 months or

●     with a history of pancreatitis.

We will stop and do not restart any antithyroid drugs if a person develops agranulocytosis and we will refer to a specialist for further management options.

For the monitoring of antithyroid drugs, we will check:

●     TSH, FT4 and FT3 every 6 weeks until their TSH is within the reference range, then

●     TSH every 3 months until antithyroid drugs are stopped, rechecking FT4 and FT3 if the TSH becomes suppressed at any stage.

We will not monitor full blood count and liver function while taking antithyroid drugs unless there is a clinical suspicion of agranulocytosis or liver dysfunction.

After stopping antithyroid drugs in adults, we will check:

●     TSH within 8 weeks of stopping the drug, then

●     TSH every 3 months for a year, then

●     TSH once a year.

●     Always rechecking FT4 and FT3 if the TSH becomes suppressed at any stage.

I will not cover the follow-up and monitoring of hyperthyroidism after radioactive iodine treatment or surgery, as this will be guided by secondary care

In terms of the management and monitoring of subclinical hyperthyroidism, that is, when TSH is low and FT4 and FT3 are normal, We will seek specialist advice if they have:

●     2 TSH readings lower than 0.1 Miu/litre at least 3 months apart and

●     evidence of thyroid disease (for example, a goitre or positive thyroid antibodies) or symptoms of thyrotoxicosis.

Otherwise, in untreated subclinical hyperthyroidism, we will check TSH every 6 months and if the TSH level is outside the normal range, we will also check FT4 and FT3.

We will consider stopping TSH measurement if the TSH level stabilises (that is, we have 2 similar measurements within the normal range 3 to 6 months apart

Let’s now have a look at thyroid enlargement with normal thyroid function

We will:

Offer an ultrasound if there is palpable thyroid enlargement or focal nodularity if malignancy is suspected.

When making decisions about whether to refer for fine needle aspiration cytology, we will take into account the ultrasound comments on echogenicity, microcalcifications, vascularity and lymphadenopathy amongst other factors.

How should these patients be managed?

Well, we will not offer any treatment in non-malignant thyroid enlargement, normal thyroid function and mild or no symptoms unless:

●     they have breathing difficulty or

●     there is clinical concern, for example, because compression is suspected.

But we will repeat the thyroid ultrasound scan and TSH, if:

●     malignancy is subsequently suspected, or

●     compression is suspected or

●     the person's symptoms worsen or

●     they develop symptoms, such as hoarseness, or shortness of breath.

Obviously, if the thyroid enlargement is causing compressive symptoms, we will refer them for further management.

We have come to the end of this episode. Remember that this is not medical advice and it is only my summary and my interpretation of the guidelines. You must always use your clinical judgement.

Thank you for listening and goodbye.