Different hypothyroid conditions tests

[Tanyaking]

Could you help me understand how central and primary hypothyroidism are diagnosed please? X

[strawberrysorbet]

Both conditions are diagnosed by blood test. In primary hypothyroidism you will have an elevated TSH but it central hypothyroidism your TSH will show as either low or normal. This is why it's important to also test your FT4 and FT3. If you have a low/normal TSH and also a low FT4 then this suggests central hypothyroidism.

In order to fully diagnose as central, you can take a further test called a TRH test which is where TRH is delivered via IV and your body's response to this is measured. If you have central hypothyroidism then your TSH will not increase even when large amounts of TRH are given to you. This is the test I had to diagnose my central hypothyroidism as my standard blood test showed a normal TSH and low FT4 but it was only just under the normal reference range. The lab told the GP this was just probably normal for me and it was dismissed. But I saw a endocrinologist privately for the TRH test who tested me and found I had a blunted response and diagnosed me with central or secondary hypothyroidism.

[Janey130 in reply to strawberrysorbet]

Do you mind me asking what meds you take ? Are they diff to a person having primary hypo ?

[strawberrysorbet in reply to Janey130]

I take levothyroxine. The drugs are the same as for primary it's just trickier to diagnose as GPs just tend to do the TSH test and that would always show as normal in someone with central hypothyroidism.

[Janey130 in reply to strawberrysorbet]

Thank you I am being treated for hypo but I reckon I have central as my tsh was always in normal range with lowish t4 ...

[Tanyaking in reply to strawberrysorbet]

Is treatment for both the same?

[strawberrysorbet in reply to Tanyaking]

Yes treatment is the same

[Tanyaking in reply to strawberrysorbet]

If my TSH is surpressed and my T4 and T3 are very low despite being on a high dose of NDT could this indicate central hyperthyroidism? Thank you for sharing,it helps hugely.x

[strawberrysorbet in reply to Tanyaking]

What were your results before you started on NDT?

[SmallBlueThing]

There's a useful article at readcube.com/articles/10.10...

I downloaded it a month ago, but it's now fuzzed-out after the first page at the link above, and no longer available for download

You can also request an article at ResearchGate: "Investigating the pathways in primary practice leading to the diagnosis of central hypothyroidism".

Edited to add: You can find the second article here: nzma.org.nz/journal/read-th...

[Tanyaking]

Can it still be central hypothyroidism if the TSH is low as well as the T4 and T3?

[Tanyaking in reply to Tanyaking]

Anyone? Xx

[strawberrysorbet in reply to Tanyaking]

Yes if TSH is low/normal and T4 and T3 are also low this suggests central hypothyroidism. You'd need to have a TRH test to confirm.