Avoid prescribing desiccated (natural) thyroid extract

Recommended treatment

An underactive thyroid is routinely treated with levothyroxine which is a licensed medicine in the UK.

Requests for DTE

National guidance does not recommend the routine use of desiccated or natural thyroid extracts (DTE) for management of an underactive thyroid (hypothyroidism).

In all cases, take a shared decision-making approach.

Unlicensed

DTE products are unlicensed in the UK. This means that their quality, safety and efficacy have not been assured by the MHRA.

Requests for new supply

DTE should not be initiated in primary care.

If people still have symptoms of an underactive thyroid while taking levothyroxine, you should:

• confirm compliance to levothyroxine dosing
• exclude other co-morbidities
• repeat thyroid function tests
• adjust levothyroxine doses to optimal symptom control
• consider stopping levothyroxine if symptoms persist with in-range TSH levels
• consider referral to an NHS endocrinologist

Levothyroxine monitoring (SPS page) provides advice on what thyroid function tests to measure and when.

DTE should be reserved for initiation by an NHS endocrinologist on a case-by-case review. This is supported by the Joint British Thyroid Association/Society for endocrinology consensus statement on the use of liothyronine (T3) in hypothyroidism.

Refer to your local policy or guidelines for DTE where available.

Requests to continue supply

Consider referring people already using DTE to an NHS endocrinologist for review.

Refer to your local policy or guidelines for DTE where available.

Switching from DTE products

Consider referring people to an NHS endocrinologist who can review if switching to levothyroxine is clinically appropriate.

NHS England has advice for endocrinologists in their article on liothyronine which includes when to continue DTE, how to stop DTE and how to start DTE.

Concerns with DTE products

People should be made aware of the following before using DTE.

Product source

DTE is extracted from pig’s glands.

Avoiding animal contents within medicines (SPS page) gives guidance on supporting people who want to avoid animal derived medicines.

Risk of hyperthyroidism

Using DTE products may lead to symptoms of hyperthyroidism and a greater risk of thyrotoxicosis compared to using levothyroxine alone.

Risk of long-term effects

Using DTE products long-term may lead to an increased risk of side effects such as osteoporosis and arrhythmia.

Difficulty adjusting doses

DTE is a combination of levothyroxine (T4) and liothyronine (T3).

Some of the levothyroxine in DTE will be converted to liothyronine after absorption. This makes it difficult to adjust the DTE dose to reach the desired therapeutic effect.

Fluctuating thyroid hormone levels

Liothyronine has a shorter half-life than levothyroxine which may cause more changes in thyroid hormone levels throughout the day than levothyroxine alone.

Levothyroxine has a longer half life of 1 week which gives relatively stable blood levels with minimal daily fluctuations.

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