Hypothyroidism — new diagnosis

PLAB 2 & PRES 3 · endocrine · easy · 8 minutes

Candidate brief

You are a doctor in a GP practice. Ms Hannah Reid, 38, has returned to discuss blood tests arranged because of fatigue, weight gain and feeling unusually cold. Her TSH is 18.6 mIU/L and free T4 is 7 pmol/L. Explain the results, assess relevant symptoms and risks, and agree an appropriate management and monitoring plan. No physical examination is required, but verbalise any examination or further assessment you would perform.

What examiners look for

Raised TSH with low free T4 indicates overt primary hypothyroidism. Positive thyroid peroxidase antibodies support autoimmune thyroiditis, commonly called Hashimoto’s thyroiditis. Antibodies do not need to be repeatedly measured. Levothyroxine replaces the hormone the thyroid is not producing. Treatment is usually lifelong, but symptoms may take several weeks or months to improve. Choose the starting dose according to age, body weight and cardiovascular disease. Older patients and people with heart disease usually require a lower starting dose and slower titration. Take levothyroxine consistently on an empty stomach with water, ideally 30 to 60 minutes before breakfast or caffeine. Iron, calcium, antacids and some other medicines can reduce absorption and should not be taken at the same time. Monitor TSH regularly until stable and then usually once yearly. Avoid overtreatment because excessive levothyroxine may cause palpitations, tremor, sweating, diarrhoea, sleep disturbance, atrial fibrillation or bone loss. Do not promise major weight loss. Some weight related to hypothyroidism may improve, but levothyroxine is not a weight-loss medicine. Pregnancy planning requires early clinical review. Levothyroxine is safe in pregnancy, should not be stopped, and the dose and blood-test frequency may need to change.

Guideline references

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