Thyroid UK
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Has anyone heard of secondary hypothyroidism/tertiary hypothyroidism/subclinical hypothyroidism ?

Just got a copy of my bloods, which all come in at 'normal' range, though all on the low side. I'm aware that a low TSH result would indicate hyper but all my symptoms are hypo (have been hypo previously) it just doesn't make sense and following seeing the Dr again this week, no further referral to endo is happening, despite the long list of on-going symptoms and having my fifth infection needing treatment since March.

Mine Normal range

TSH 0.64 0.5 - 5.0

T4 13.4 10 - 24

T3 4.45 4 - 8.3

The last 3 results are all pretty much the same without much movement, and remaining low in the normal range. Dr wrote that the antibodies were negative and came in middle of 0 - 100 normal range.

Crumbs how do we make sense of measuring these together when Drs don't!!!!

12 Replies

Secondary hypothyroidism is when insufficient TSH is produced (usually a form or hypopituitary).

Tertiary hypothyroidism is sometimes used when the problem lies in the hypothalamus not producing enough TRH (which then means the pituitary does not produce enough TSH).

Subclinical hypothyroidism is (sometimes) defined as " increased thyrotropin-stimulating hormone (TSH) levels in patients whose free thyroxine (T4) levels are not below normal".

An older (now archived) section of Thyroid Manager might be of interest:



Thank you for replying and for the useful info, I'll click on that link and hopefully get some information, I just can't make sense of the results and came across secondary/tertiary/subclinical as possible options for my low results but with with hypo symptoms etc. Thanks again


The results would NOT make sense in anyone without something unusual going on. You are quite right.

Note that both secondary and tertiary are sometimes called "central hypothyroidism" - the central control mechanisms are not working so you end up with insufficient thyroid hormone. It could be that you actually have no problem with your thyroid itself and, if you produced more TSH, it would produce more thyroid hormone.



Hi Often when you are sure that you are Hypo the bloods do not show it to start with. You will need retests in ,hopefully 6 months. Worth also having your vit D tested as hormonal , iron/ferritin ( needs to be well in range)and B12 + foliates, autoimmune and hormonal needs to be well in range.Also Diabetes status, autoimmune and hormonal, similar symptoms to Hypo. at first.

Your lowish TSH could be Pituitary gland as on the low side, often just naturally is. However if you have ever had even a very mild head injury, especially as a child, it should be tested. Simple test, 24 hour urine collection.

I hope that gives you some ideas.

best wishes,



Thank you Jackie for your reply. I've been getting monitored for 3 years, when I was being treated for hypo briefly 3 years ago. I have previous history of being hyper and hypo and my symptoms continue to be hypo and this year are so much worse. I eat below my daily intake of cals, exercise - have even been sick and not eaten but not an ounce shifts (this year since being particularly sick). GPs are leaving it all there with no referral to endo. I am on iron supplements for low iron, which made a slight difference. I haven't had a head injury, as far as I'm aware. I had a scan about 3 years ago because of daily headaches and my pituitary was fine then, though no further testing happened after this. At a loss and left with all the symptoms and being so ill, this is not me and all my pro-active actions are wasted and making no difference unfortunately. Considering going private but if it's not my thyroid then that would be a waste of money.

When I looked up my tests, it said that being in the low end of range with tsh, t4 and t3, could mean thyroid and pituitary but tertiary/secondary hypo so I'll look this up further.

Thank you again


Hi We only get the reply if you click on the reply to this under that post. Just found it. It sounds like you need a bit of T3 to me, not too much. So long as you have had the 24 hour urine test for pituitary gland, the best one. Some docs think low TSH means that FT3 cannot be treated especially GP`s. My TSH is immeasurable, so low. Always has bee,no cause ever found., I need T4 and T3. If FT3 too low weight and other symptoms can be a big problem but do not let the FT3 go over range.


Sorry, must be a hold up with TUK ,just received your original answer! A scan of pituitary gland would not show how it is working, only a 24 hour urine test shows that.personally ,I would see a good endo, private or NHS, check one out first, you will need a referral. GP`s mostly think thyroid disease is common so easy to deal with, it is common but really so complicated.I do think, if you feel "off" you need to explore the thyroid thoroughly first with a good specialist.

Best wishes,



Hi jackie, I'm just looking through some old posts to try and understand my thyroid situation and came across this one. I wonder if you could clarify the test you mention for pituatry function. Would this be a 24 hour urine collection for cortisol?


Hi fixit, I did a 24 hr urine collection and creatinine came up with high levels. I looked this up and it refers to kidney function but is also used to test adrenals apparently as it was my adrenals they were testing. Following pleading with a gp I finally managed to get an endo referral to raigmore hospital in Inverness so am waiting for it to come through. I've had no further bloods for thyroid taken but symptoms continue. Test for pituitary function would be good to know. Cortisol is adrenals but of course it's all connected. Apparently the tsh test measures the signal that the pituitary gland sends to the thyroid, which doesn't make it accurate on its own re the thyroid


Hi Sorry been in hospital, just come out.

Secondary can also be due to Parathyroid. this requires initially a blood test Am for pTH, calcium and vit D. Must be Am and all 3. If all high or D high for you and the others well over range. Nuclear scan for pTH and ultra sound for thyroid.

Yes, the 24 hour urines are 2 separate things done separately. 24 hour urine collection only ( home) is for Pituitary gland, usually shows by low TSh, very low. The cortisone test for adrenals , is a 24 hour urine, with a tiny cortisone prescribed for midnight. Then a blood test at 9am at the end of the rest. My Endo says it is the only test that is ok

Best wishes,



Thank you Jackie, I hope you are ok. I will see what the outcome of my ultrasound is and discuss further with my GP.


Low or suppressed TSH does NOT indicate hyperactivity it depends how you FEEL!!


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