Could you help me understand how central and primary hypothyroidism are diagnosed please? X
Different hypothyroid conditions tests - Thyroid UK
Different hypothyroid conditions tests
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.
Do you mind me asking what meds you take ? Are they diff to a person having primary hypo ?
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.
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...
Can it still be central hypothyroidism if the TSH is low as well as the T4 and T3?