What should you know about a TFT blood test?

TFT usually refers to thyroid function tests. The blood sample may be used to measure thyroid-stimulating hormone and thyroid hormones. Results are read together rather than in isolation, because illness, medicines, pregnancy and the reason for testing can affect interpretation. A result outside the laboratory range does not by itself establish a diagnosis. It may prompt repeat testing, a review of symptoms, or other assessment. Symptoms such as tiredness, changes in weight, feeling unusually hot or cold, tremor, or changes in bowel habits can have several causes. Thyroid testing may therefore be one part of a wider clinical picture.

Follow the instructions given by the clinician or laboratory. Tell the team about prescribed medicines, supplements and any thyroid treatment before the sample is taken. Do not stop a medicine unless the prescriber tells you to. Ask when the result will be available and whether you need a follow-up appointment. Your clinician may compare the result with earlier tests, examine your neck, or arrange further blood tests. Conditions such as anaemia, coeliac disease and chronic kidney disease can also cause symptoms that overlap with thyroid problems, so avoid interpreting one result without context.

Arrange routine medical advice if symptoms persist, a result has been flagged, or you are taking thyroid medicine and need monitoring. Seek urgent help for severe breathing difficulty, chest pain, fainting, marked confusion, or a very fast or irregular heartbeat, especially if these symptoms are new or worsening.

Which thyroid tests were measured, and what do they show together? Could any medicine or supplement have affected the result? Do I need repeat testing or an examination? Which symptoms should prompt earlier review?