Interpreting unusual thyroid function tests

Thyroid conditions are among the most common endocrine disorders.

Laboratory tests are crucial in the diagnosis and management of most of these conditions.

Thyroid function tests (TFTs) are the most commonly ordered endocrine tests in both outpatient and inpatient settings and constitute more than 60% of endocrine tests. In general, it is not difficult to interpret thyroid function tests; however, when the results are discordant or incongruous with the clinical picture, their interpretation can be challenging.

Learning objectives:

1. Understand the regulation of thyroid status and factors governing thyroid hormone action.
2. Know the different TFT patterns and identify causes.
3. Know common confounders and assay interference.
4. Know about drugs that can trigger thyroid dysfunction and interfere with oral thyroid hormone therapy.

Acknowledgements

Content created by Dr Parvathy Chandra MRCP UK, MRCP Endocrinology, FRACP.