NICE has published new guidance about the investigation, treatment and management of primary thyroid disease and recommended new research into the clinical and cost effectiveness of levothyroxine (T4) and liothyronine (T3) combination therapy.

The guideline covers investigating all suspected thyroid disease and managing primary thyroid disease (related to the thyroid rather than the pituitary gland). It does not cover managing thyroid cancer or thyroid disease in pregnancy. It aims to improve quality of life by making recommendations on diagnosis, treatment, long-term care and support.

It was recommended that verbal and written information should be presented to patients at each stage of their diagnosis and treatment. A move welcomed by patient charities as it will "enable them better informed about their condition and in a stronger position to make shared decisions about their care."

Key information for patients is that thyroid disease usually responds well to treatment and that the goal of treatment is to alleviate symptoms and align thyroid function tests within or close to the reference range.

Also that people may feel well even when their thyroid function tests are outside the reference range and symptoms may lag behind treatment changes for several weeks to months. It was also considered important to let patients know that day-to-day changes in unexplained symptoms are unlikely to be due to underlying thyroid disease because the body has a large reservoir of thyroxine.

When to test for thyroid dysfunction

NICE say to consider tests for thyroid dysfunction for adults, children and young people if there is a clinical suspicion of thyroid disease, but bear in mind that one symptom alone may not be indicative of thyroid disease.

Tests for thyroid dysfunction should be considered for adults, children and young people with depression or unexplained anxiety or for children and young people with abnormal growth, or unexplained change in behaviour or school performance.

It adds to be aware that in menopausal women symptoms of thyroid dysfunction may be mistaken for menopause.

Managing primary hypothyroidism

Levothyroxine should be offered as first-line treatment for adults, children and young people with primary hypothyroidism. Liothyronine for primary hypothyroidism should not be offered, either alone or in combination with levothyroxine, because there is not enough evidence that it offers benefits over levothyroxine monotherapy, and its long-term adverse effects are uncertain.

It doesn't recommend offering natural thyroid extract for primary hypothyroidism because there is not enough evidence that it offers benefits over levothyroxine, and its long-term adverse effects are uncertain.

NICE say to consider starting 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. Consider starting levothyroxine at a dosage of 25 to 50 micrograms per day with titration for adults aged 65 and over and adults with a history of cardiovascular disease.

Recommendations for research

A spokesperson from the British Thyroid Foundation (BTF) said: "The BTF was one of the stakeholders in the consultation process and we invited our members, and other patients and carers, to share their views and comments on the guideline documents.

"Importantly, the process highlighted that there is still a number of areas where further research is needed to determine the best course of treatment for some thyroid patients. 

"These include studies that will improve understanding on the effectiveness and long-term safety of the existing treatments for people with hyperthyroidism, and also more research into levothyroxine/liothyronine combination therapy for hypothyroidism. We welcome all the research recommendations that have been identified."