Advice Please - low FT4 but TSH at low end of range

[Buckmcbecky]

Hi all, I have been having thyroid type symptoms for years and a strong maternal family history of underachieve thyroid. I have also noticed that my neck has swollen recently. I have repeatedly asked for my thyroid to be tested only for TSH to be looked at. I am suffering from severe depression and my psychiatrist suggested the thyroid be looked at again. Unfortunately, my GP isn't interested. A medichecks test gave these results:

TSH 2.91 miU/L

Free T3 4.08 pmol/L

Free Thyroxine 11.6 pmol/L

The two antibody tests were normal.

Does anyone have any helpful advice and/or recommendations for good endos in the Gloucestershire area (by PM of course). I would be particularly interested in whether my antidepressant medication could be having an effect on my results. (Venolfaxine). Many thanks in advance to you all.

[m7-cola]

I am sure that someone with better knowledge than me will be along soon. It will be helpful to them if you add the ranges to those test results.

[SeasideSusie Remembering]

Buckmcbecky

Adding the reference ranges to your results will mean that those members who aren't familiar with Medichecks ranges can interpret them.

However, I know the ranges:

TSH 2.91 miU/L (0.27-4.2)

Free T3 4.08 pmol/L (3.1-6.8)

Free Thyroxine 11.6 pmol/L (12-22)

Did the Medichecks comments point out that your FT4 (free thyroxine) is below range? What did the comments say?

How "normal" were the antibody tests? Please can you give the actual results.

[Buckmcbecky in reply to SeasideSusie]

Thanks both, you can see I am new to this! You have the ranges correctly. The medichecks advice was to re-test in three months as low T4 could be transient.

The antibody tests were

Thyroglobulin antibodies 14.7 kU/L (range <115)

Thyroid Peroxidase Antibodies 10.4 kIU/L (range 14.7)

[SeasideSusie Remembering in reply to Buckmcbecky]

Thanks

There are two possibilities here.

1) You have autoimmune disease (aka Hashimoto's) which is confirmed by raised antibodies. Antibodies fluctuate and it could be that you tested when they were low, another test may show them to be high, it's a matter of catching them at the right time. You can also have Hashi's without having raised antibodies apparently, just to complicate things. Between 80-90% of hypothyroidism is caused by Hashi's.

By the way, the range for TPO antibodies is <34

2) You could have Central Hypothyroidism. This is where TSH can be normal, low or slightly elevated, with a low FT4. Your TSH and FT4 fit this criteria.

I agree with Medichecks to repeat the test, if it comes back again similar to this test then consider Central Hypothyroidism. [You don't really need to wait 3 months, you could repeat the test in 2 months.]

Central Hypothyroidism is where the problem lies with the hypothalamus or the pituitary rather than a problem with the thyroid gland. With Central Hypothyroidism the TSH can be low, normal or slightly raised, and the FT4 will be low. It could be due to a problem with the pituitary (Secondary Hypothyroidism) or the hypothalamus (Tertiary Hypothyroidism), the term Central Hypothyroidism is an umbrella term and distinguishes this problem from Primary Hypothyroidism where the TSH would be high i.e. over range, and usually doctors wait until it reaches 10 before diagnosis.

Your GP can look at BMJ Best Practice for information - here is something you can read without needing to be subscribed bestpractice.bmj.com/topics... and another article which explains it ncbi.nlm.nih.gov/pmc/articl... You could do some more research, print out anything that may help and show your GP.

As Central Hypothyroidism isn't as common as Primary Hypothyroidism it's likely that your GP hasn't come across it before. You may need to be referred to an endocrinologist. If so then please make absolutely sure that it is a thyroid specialist that you see. Most endos are diabetes specialists and know little about the thyroid gland (they like to think they do and very often end up making us much more unwell that we were before seeing them). You can email Dionne at

[e-mail]

for the list of thyroid friendly endos. Then ask on the forum for feedback on any that you can get to. Then if your GP refers you, make sure it is to one recommended here. It's no guarantee that they will understand Central Hypothyroidism but it's better than seeing a diabetes specialist. You could also ask on the forum if anyone has been successful in getting a diagnosis of Central Hypothyroidism, possibly in your area which you'll have to mention of course.

[Buckmcbecky in reply to SeasideSusie]

Thank you so much, very helpful