What Does Borderline/Subclinical Hypothyroid Mean?

I hate the term ‘borderline hypothyroid’ or ‘subclinical hypothyroidism’. It leaves many people undiagnosed and ill. Many just get worse and worse with time. 

I was told that I was ‘only borderline’ and to come back in a few months, where the doctor would review it again. I was already feeling bad by that point, but after a few more months, I was feeling absolutely dreadful. I was still classed as ‘mildly hypothyroid’ at that point, but my doctor gave me a starting dose of Levothyroxine to see how I got on because I complained of such poor health and many hypo symptoms.

I basically feel that the term ‘borderline hypothyroid’ or ‘subclinical hypothyroidism’ is used when a doctor acknowledges that your thyroid isn’t performing too well, but it’s not yet ‘bad enough’ to receive medication. And this is disgusting. Why should we be aiming for anything less than optimal, when the thyroid gland is in charge of so many functions in the body?

The problem is that many doctors just go by TSH, which isn’t accurate on its own, and while this can only be ‘mildly’ bad, Free T3 and T4 levels can be low. Being optimal can make all the difference for a lot of people, but subclinical/borderline hypothyroidism leaves many people with low levels in Free T3 and T4, causing on-going symptoms, because they are actually hypothyroid.

Not only is going by TSH alone inaccurate in diagnosing and treating hypothyroidism, but subjecting everyone to outdated ranges is problematic since may of us see the effects of a high TSH differently. For example, the range my doctor used was 0.5-5, and I felt very very ill at 6, which is just above range; borderline. I’ve heard some people get to 50 or even 100 before feeling unwell. Therefore, we should be treated individually. Ranges also differ from lab to lab.

A TSH of 2 or below is recommend by many sources these days, and even if you’re classed as borderline with a TSH reading of 6 on a 0.5-5 range, then this can be causing you a lot of symptoms. The same goes for a Free T4 of 11 when the range is 10-20, for example. These ranges do not take in to account where each individual feels best and doctors should be working to find this sweet spot for each patient, when they show classic hypothyroid symptoms. We’re individuals and deserve to be treated as such.

Since we didn’t have our TSH, Free T3 and Free T4 levels tested when our thyroid function was good, we don’t know our individual optimal levels, so we must work to find this and return it to normal with thyroid medication, diet, lifestyle changes etc. For many people, they need medication or it won’t get any better.

If your doctor has said you’re borderline or subclinically hypothyroid, then I strongly suggest you get another doctors opinion, and possibly another, and another until you’re happy. You should also have a retest of any borderline/subclinical TSH, Free T3 or Free T4 readings to see if they have gotten better or worse. They can occasionally get better, but for many, they get progressively worse.

It is also worth noting that Hashimoto’s, an autoimmune disease that causes about 90% of all hypothyroid cases, can cause TSH levels to swing, so if you still feel unwell and have blood test results that seem to get better and worse again, it’s likely you have Hashimoto’s, which definitely needs addressing. I therefore support everyone who has or thinks they have thyroid issues, to also test TGAB and TPOAB.

You can click on the hyperlinks in the above post to learn more and see references to information given, but more reading and references can also be found at:



Written by Rachel, The Invisible Hypothyroidism

Rachel is a Thyroid Patient Advocate and Expert with Six 2018 WEGO Health Award Nominations. She is a highly ranked writer appearing in the Top Hypothyroidism Websites and Top Thyroid Websites 2018, and is a qualified Diet and Nutritional Advisor, also currently studying for relevant qualifications and certificates in Life Coaching, Motivational Speaking, Reflexology and more. She has worked with The National Academy of Hypothyroidism, The BBC, The Mighty, Dr. Hedberg, Thyroid UK and ThyroidChange, to name just a few. She is well recognised as a trusted and useful contributor to the thyroid community.

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