Blood Tests (unanswered question)

[supressedtsh]

At a BTF meeting I listened to a talk about thyroid blood tests from a person who was in charge of the laboratories.

I would like to ask the experts here the same question as I asked at the BTF meeting - why is the Free T4 blood test not done when the TSH is within range?

Why can we only have our Free T3 tested when an Endocrinologist requests it?

When treating hypothyroidism it is ridiculous to monitor the patient by the TSH. The TSH can be affected by so many things. The Free T4 gives a far better picture.

[Dr Petros Perros]

The FT4 level can be helpful, but depends on the context. In the overwhelming majority of cases the FT4 is predictably normal if the serum TSH is in the normal range. So the serum TSH is a very good screening test. In some rare cases it will miss hypothyroidism (for instance when the problem lies in the pituitary rather than the thyroid). So knowing what the symptoms of the particular patient are and whether other pituitary hormonal deficiencies are present are a good guide in deciding how to utilise the various available tests most efficiently. Remember that doing too many tests for no good reason is bad medical practice and often can mislead. So, it makes sense that the person who requests these tests is knowledgeable and this may be regarded as justification for limiting it to endocrinologists. I personally don't think this is a good approach as I have many colleagues in other specialities including in general practice who are very knowledgeable on endocrine problems and can make equally good judgements as endocrinologists.

When treating hypothyroidism I believe it is important to monitor the patient. The objective is to ameliorate the symptoms of hypothyroidism and hit the biochemical targets.