Case 36 A woman with fatigue and weight gain

Christina consulted Dr Francis in January 2008. She was worried because she felt tired all the time and had put on weight. A friend who had similar symptoms had been treated with thyroxine for an under-active thyroid and Christina wondered if she might have the same problem. Christina had always been a little over weight and had sought medical advice regarding this before. She did not have any other features to suggest hypothyroidism. She was not taking any medication but had a Mirena for contraception. Her grandmother had had some sort of thyroid problem.

Dr Francis performed a blood test to check the FBC and TSH. The results were normal. The TSH was 5.0 mmol/l.

Christina returned in February to discuss the results. Despite the normal TSH she wanted to try thyroid replacement.

What would you do now?

Dr Francis repeated the TSH and checked for TPO antibodies. Again the TSH was normal at 4.5 mU/l. The TPO antibody tire was 5 IU/l (normal). A few years earlier Dr Francis had looked after a similar patient who had seen a private endocrinologist and been treated with thyroxine. He therefore decided to treat Christina despite the normal thyroid function tests. He prescribed thyroxine 25 micrograms daily. The dose was gradually increased to 100 micrograms daily over the following six months. TSH measurements in April, June and August were 1.0 mU/l, 0.2 mU/l and 0.1 mU/l respectively. On the last occasion the free T4 was 25.1 pmol/l (just over the normal range).

Would you have done the same?

In November Christina came to see another partner at the practice complaining of palpitations and breathlessness. On examination she was in atrial fibrillation. This was attributed to the thyroxine that she was taking.

It was alleged that Dr Francis was negligent because no competent doctor would diagnose hypothyroidism with normal blood tests.

Expert comment

Hypothyroidism is relatively common. The annual incidence is 3.5 per 1000 women and 0.6 per 1000 men (Vaidya & Pearce, 2008). The symptoms of hypothyroidism (such as fatigue, weight gain or feeling cold) are very nonspecific. Many people without thyroid disease experience these symptoms and seek medical advice. There is good evidence that patients with symptoms suggestive of hypothyroidism but with normal thyroid function do not benefit, either physically or psychologically, from treatment with thyroxine (Pollock et al., 2001)

To answer uncertainties about the use of thyroid tests the Association for Clinical Biochemistry, the British Thyroid Association and the British Thyroid Foundation produced evidence-based guidelines in June 2006.

Thyroxine has been used, particularly in non-NHS clinics, to treat nonthyroid disease such as obesity, chronic fatigue, infertility, menstrual irregularity and short stature (Roti et al., 1993) This has been a cause for concern within the medical community.

In response to these concerns the Royal College of Physicians and the British Thyroid Association produced a policy statement to clarify preexisting guidance in 2008 (RCP/BTA, 2008). This policy statement and the UK Guidelines for the Use of Thyroid Function Tests produced by the Association for Clinical Biochemistry and the British Thyroid Association in July 2006 (ACB/BTA, 2006) give the following guidance for the diagnosis of primary hypothyroidism:

• A TSH >10 and a Free T4 below the reference range are required for the diagnosis of primary hypothyroidism.
  
• A TSH within the normal range excludes primary hypothyroidism (as long as the patient is not taking any medication known to affect the TSH).
  
• Patients with a normal TSH should not be diagnosed with hypothyroidism and should not be treated with thyroxine.

The diagnosis of hypothyroidism must be made on the basis of biochemical tests and not on the basis of clinical symptoms alone.

The inappropriate use of thyroxine is harmful.

• It exposes patients to possible or, as in this case, actual harm. Hyperthyroidism is known to be associated with atrial fibrillation.
  
• A nonthyroid cause of the symptoms may be missed.

In this case Dr Francis should not have diagnosed hypothyroidism or given Christina thyroxine. If Dr Francis had been concerned that Christina had secondary hypothyroidism she would have had other symptoms to suggest pituitary failure such as headache, visual field disturbance, cranial nerve palsies (II, IV or VI) or features of other endocrine deficiencies such as amenorrhoea, loss of libido etc. Specialist referral would have been required. In addition he did not explore other possible causes for the patient’s symptoms such as mental health issues or diabetes.

Legal comment

Dr Francis’s MDO will have to settle this claim. It is clearly indefensible. However, damages will be low, as there will be no long term sequelae from the treatment.

Dr Francis may try to argue that he was following the treatment given by a private endocrinologist in a previous patient. Putting it bluntly, this will not wash. He should assess each patient on his or her condition and in an appropriate manner. If such thinking was communicated to Christina, it may provoke a complaint to the GMC, calling into question Dr Francis’s fitness to practise.

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