Published 26 March 2009, doi:10.1136/bmj.b725
Cite this as: BMJ 2009;338:b725

Editorials

Diagnosis and treatment of primary hypothyroidism

New guidance highlights how to do it in primary care

Primary hypothyroidism or underactivity of the thyroid gland is common and is usually managed in primary care.¹ In recent years, increasing numbers of patients with and without confirmed thyroid disease have been diagnosed and treated inappropriately using levothyroxine and other thyroid hormones. Management that falls outside good practice as defined nationally and internationally by accredited thyroid experts may compromise patients’ safety. This is potentially an enormous problem, given that in any one year one in four people in the United Kingdom have their thyroid function checked.^{2 3}

The Royal College of Physicians, working closely with several specialist professional associations and patient associations with interests in the safe management of thyroid diseases, has recently produced a statement on the diagnosis and management of primary hypothyroidism. This statement sets out clear guidance for general practitioners and the wider medical profession regarding the diagnosis and treatment of primary hypothyroidism in the United Kingdom.³ The box summarises the key messages of this statement.

Diagnosis and management of primary hypothyroidism3 Diagnosis Symptoms of hypothyroidism are common in other conditions and in normal health. Clinical symptoms and signs are insufficient to make a diagnosis of hypothyroidism, and thyroid function tests are essential The only validated test for thyroid function is the measurement of serum thyroid stimulating hormone (TSH) and free thyroxine (T4) These tests can be affected by non-thyroidal illnesses. In these circumstances, test results return to normal after the illness resolves, and thyroid hormone therapy is not needed and may be harmful Different assays may give different results, and there is an initiative to standardise reference ranges and units Treatment The aim of treatment is to render the patient euthyroid; this is best achieved with levothyroxine alone. When adequate levothyroxine is given to lower the TSH to within the reference range, symptoms of hypothyroidism resolve; in some patients fine tuning of TSH within the reference range may be needed Patients with ongoing symptoms after appropriate thyroxine treatment should be investigated to diagnose and treat the cause No scientific evidence supports the addition of tri-iodothyronine (T3) to levothyroxine in any currently available formulation, including Armour thyroid (dessicated animal thyroid extract) Treatment with T3 can have adverse effects on bone (for example, osteoporosis) and the heart (for example, arrhythmia), and Armour thyroid contains excess T3 in relation to T4 that is not consistent with normal physiology Treatment of subclinical hypothyroidism Subclinical hypothyroidism is defined as a TSH value above the upper limit of the reference range with a free T4 concentration within the reference range. Some patients, especially those with a TSH value greater than 10 mIU/l, may benefit from treatment with levothyroxine Patients with normal thyroid function tests Patients with thyroid function tests within the reference ranges who have continuing symptoms, whether they are taking thyroxine or not, should be investigated for a non-thyroidal cause of their symptoms; an opinion may be sought from an endocrinologist or general physician

So why have problems arisen regarding the diagnosis and treatment of hypothyroidism? The answer lies in the epidemiology and pathophysiology of this disease. Hypothyroidism is common and is becoming more prevalent because of increased life expectancy and an ageing population. Thyroid hormones affect most organs, so hypothyroidism presents with symptoms that can mimic other conditions. Although hypothyroidism may be missed and other conditions such as depression diagnosed instead, patients are increasingly being diagnosed with hypothyroidism in the absence of abnormal thyroid function tests.

An incorrect diagnosis of hypothyroidism could expose some patients to the harmful effects of excess thyroid hormones and other serious conditions may go undiagnosed.⁴ In other patients, adequate replacement with levothyroxine does not resolve symptoms, which are attributed to hypothyroidism rather than other conditions that may coexist, such as depression.

A plethora of information is available on the internet, and media interest in alternative modes of diagnosis and treatment of hypothyroidism is high. This has caused an increase in requests for inappropriate investigations and non-standard treatments, as well as referrals to non-accredited practitioners.^{3 4} These factors have led to a rise in awareness and confusion about hypothyroidism, and they have increased the workload in primary care.

In most cases the management of primary hypothyroidism is straightforward and should be undertaken in primary care. Secondary hypothyroidism is the result of pituitary disease and its treatment, and it should be managed only by specialist endocrinologists. Likewise, patients who take levothyroxine for thyroid cancer should be treated only in a specialist thyroid cancer clinic.

Normalisation of thyroid stimulating hormone means a return to normal health in most patients with primary hypothyroidism. If wellbeing is not restored despite normal concentrations of thyroid stimulating hormone, it is important to exclude other conditions as the cause of ongoing symptoms. If no obvious cause is found the patient should be referred to an accredited hospital endocrinologist or general physician.

Cite this as: BMJ 2009;338:b725

¹ Department of Endocrinology, Sheffield Teaching Hospitals NHS Foundation Trust, Royal Hallamshire Hospital, Sheffield S10 3JF

---

Competing interests: None declared.

Provenance and peer review: Commissioned; not externally peer reviewed.

References

1. Vaidya B, Pearce SHS. Management of hypothyroidism in adults. BMJ 2008;337:a801.[Free Full Text]
2. UK guidelines for the use of thyroid function tests. 2006. www.british-thyroid-association.org/info-for-patients/Docs/TFT_guideline_final_version_July_2006.pdf.
3. Royal College of Physicians. The diagnosis and management of primary hypothyroidism. 2008. www.rcplondon.ac.uk/specialties/Endocrinology-Diabetes/Documents/Hypothyroidism.pdf.
4. Weetman AP. Whose thyroid hormone is it anyway? Clin Endocrinol (Oxf) 2006;64:231-3.[CrossRef][Medline]

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