Informational Posts

Why Going by TSH Alone Is Problematic

Originally published on 12th February 2016
Last updated on 25th March 2024

Browse thyroid patient communities online and you’ll find hoards of people saying that doctors testing only TSH (thyroid stimulating hormone) is keeping many people undiagnosed, untreated or under-treated.

Why? Let’s explore.

LetGetChecked Thyroid Test

Firstly, What is TSH?

TSH stands for ‘Thyroid Stimulating Hormone’ and is a hormone secreted by the pituitary gland. It serves as an average read out over the previous four to six weeks of your thyroid levels.

TSH is a pituitary hormone that sends a signal to the thyroid gland. It is produced by the pituitary gland.

It goes something like this (this is very simplified):

Hypothalamus -(sends signal to)-> Pituitary -(sends signal to)->Thyroid

Theo The Thyroid Plushie

With a healthy thyroid gland, the pituitary gland ‘knocks on the thyroid’s door’, signalling it to work and produce so much thyroid hormone.

It does this by releasing TSH. The thyroid gland ‘answers the door‘ and does what it’s told by the pituitary by releasing the correct amount of thyroid hormone. Therefore, the pituitary gland isn’t having to knock too much, which equals a low TSH.

This is generally seen as good. A low TSH usually means that the thyroid is producing the correct amount of thyroid hormones.

TSH in Hypothyroidism

However, in a person with an underactive thyroid (hypothyroidism) and not medicated, the pituitary gland knocks on the door of the thyroid gland, trying to give instructions, but the thyroid gland ignores it. It doesn’t respond.

The pituitary gland bangs harder and louder on the door, as the thyroid gland continues to ignore it, and doesn’t produce the hormones it should be. This equals a high TSH. This isn’t good.

Bringing TSH Down

Theoretically, if you manually put the thyroid hormones your body is lacking and thyroid is failing to produce, in to your body (via thyroid medication; ‘hormonal replacement’), the TSH level will come down, as the pituitary gland doesn’t need to knock on the door so much. It can see that the body is getting the hormones it needs. So doctors generally see the TSH level being low as your body having what it needs. 

However, this isn’t always the case.

As TSH is a pituitary hormone, not a thyroid hormone, it does not tell you your actual thyroid hormone levels. It does, however, give an indication of them.

Free T3 and Free T4 need testing to check actual thyroid hormone levels and the full thyroid panel should be used as much as possible, to get the most comprehensive view of your thyroid health. 

The Full Thyroid Panel consists of:

  • TSH
  • Free T3
  • Free T4
  • Thyroid antibodies (thyroglobulin and thyroid peroxidase) where possible

(see here why testing Reverse T3 is often controversial and why I’m dubious about whether it’s truly useful. I lean more towards ‘no’, however, you will see other thyroid resources suggesting we must have it checked.)

‘Normal’ TSH Levels

An analogy you could use when your doctor tells you that your TSH is fine, but you don’t feel ‘fine’ could be;

Would you be happy with a heating engineer telling you your central heating is working fine, just because the thermostat reading is normal, when the radiators are cold and the house is freezing?

Theo The Thyroid Plushie

As one study states:

“Screening exclusively with TSH will result in misdiagnosis of some cases, whilst other conditions may be missed altogether (by virtue of returning a TSH result that falls within the reference range despite overt hypothalamic–pituitary–thyroid dysfunction).” [1]

Still Tired T Shirt and Tea

You can still feel unwell with a ‘normal’ TSH level because:

Going Forward

The next time your TSH is ‘normal’ and you still feel unwell, one of the above reasons could well be why. Many thyroid patients find that whilst their TSH is OK, their Free T3 and Free T4 isn’t optimal and so they still feel unwell. You should always be working to optimise your levels. 

If your doctor won’t test a full thyroid panel, you may explore ordering your own from online lab services.

Medichecks is a popular place in the UK, where you can order the all important thyroid function test, and thyroid antibodies to check for autoimmune hypothyroidism (Hashimoto’s).

LetsGetChecked cover most countries, and offer the thyroid function testHashimoto’s testing and many more, all from the comfort of your own home.

Theo The Thyroid Plushie


Now you know all of this, please don’t stay undiagnosed, under-medicated or be dismissed due to just having only TSH tested. It should form part of the picture, but not all of it.

Obtain a copy of your test results and have a look for yourself. Ensure you’re having the full thyroid panel tested to get the most comprehensive view of your thyroid health.

TSH gives an indication of what’s going on, but not the full picture.

Related Post: TSH Is Still an Important Thyroid Test by Dy Henderson

Did you know that TSH alone isn’t accurate? Share your thoughts in the comments section below.

You can click on the hyperlinks in the above post to learn more and see references to information given.

Be Your Own Thyroid Advocate Book CoverSee also:

The book Be Your Own Thyroid Advocate: When You’re Sick and Tired of Being Sick and Tiredwhich builds on this article in detail and tells you everything you need to know to become an active participant in your own thyroid health and understand what you can do to get better.



About Author

Rachel Hill is the highly ranked and multi-award winning thyroid patient advocate, writer, speaker and author behind The Invisible Hypothyroidism. Her thyroid advocacy work includes writing articles, authoring books, producing her Thyroid Family email newsletters and speaking on podcasts and at events about the many aspects thyroid disease affects and how to overcome these. She is well-recognised as a crucial and influential contributor to the thyroid community and has a large social media presence. Her bestselling books include "Be Your Own Thyroid Advocate" and "You, Me and Hypothyroidism".


  • Magda Keyser
    February 27, 2024 at 7:32 pm

    Hi my dr only test the Free T4 and TSH and results and almost every Dr in town test only them
    Free T4 15.5
    TSH 0.02
    According to the lab my Eltroxin dose is to high
    150 (Eltroxin)
    Any advice please I can fo the tests on my own but where to with the results

  • Elke Crump
    May 29, 2023 at 6:42 pm

    My TSH was “normal” for decades (treated and untreated). Only when I learned that T4 AND T3 play an important role, I tested privately and found that my FT4 was at 48% through the interval and FT3 at the very bottom or below. This did not matter to doctors at all. Blame was laid at my door for feeling unwell (exercise, diet, refusal to take antidepressants etc.). Then I found a nurse practioner who treated by symptoms. My FT3 is now at 85% and my FT4 around 62%. The TSH totally tanked way below reference interval, but I feel so much better (most of the time). I will never be able to see a doctor again without causing them to flip out and threaten me with CV problems or osteoporosis or thyroid storm (and who knows what else). Even if all that ever came to pass, I am happy to take my chances after suffering for 50 years. Even if my life were to be cut short by this treatment, at least it is a life.

  • Glenda Dredge
    April 6, 2023 at 12:31 am

    Hi, just joined this support group. I was diagnosed 12 months ago with an underactive thyroid and commenced on levothyroxine, it has taken me this long to get the GP to increase my dose. I have had to fight all the way, I was informed by the receptionist that my results were normal but I still felt so very unwell, I got a printout of my results and discovered that my TSH was still above range so requested to speak to a doctor. He reluctantly increased my dose from 50mcg to 75mcg.
    Still feeling rubbish after 12 weeks I increased my dose to 100mcg and told the GP I had done this, I was asked to make an appointment ( which I had been trying to do but not getting anywhere). I saw a practice nurse who suggested I double my HRT dose as I still felt awful, this just gave me migraines everyday, so went back to usual dose. After much persuasion I finally got my levo increased to 125mcg, I cited the N.I.C.E. Guidelines to them which state they should take the patient’s symptoms into account when treating. I feel better than I did but far from well, some symptoms have improved but others are no different. I’m not as tired but then I’m only working on an as and when basis now, I took early retirement believing my symptoms were caused by stress at work. I am a registered nurse of over 40 years.
    I truly believe I have been symptomatic for many years, I’ve had endoscopy for gastric pain and reflux, mainly resolved now even though my gastric tablets have been halved. I’ve seen physiotherapists because of joint pains. I’ve tried inhalers as I get really short of breath with minimal exercise. I’ve had a persistent irritating cough for many years, which I have complained about several times, I got a chest X-ray and told it was normal, they have done nothing since.
    I still get very tired and have aches and pains everywhere but the hardest part is trying to explain to my husband and sons that I’m not lazy, I’m just exhausted all the time. Why I’m depressed.
    I have eventually got another appointment with the GP surgery but again it’s with a nurse practitioner who will be unable to make any alterations to my dose of levo.
    P.s. I got my T3 and T4 done privately and my levels are midway in the normal range, my TSH is in the lower end of the normal range. I just want to feel well, be able to keep the house tidy, play with my 6 year old grandson, climb steps, hills etc without having to stop and get my breath back, lose the excess weight, go to the gym with my husband. WHY DO WE HAVE TO FIGHT FOR OUR TREATMENT. I want to be able to enjoy my retirement and do things with my family. Sex would be nice occasionally!

  • Mike Sharp
    November 3, 2022 at 9:22 am

    Had been balanced on 200mcg Levothyroxine for 10 years. Changed doctor who looked at low TSH and high T4, and decided I was overdosed. She was obsessed by risk of heart and bone problems, so reduced Levothyroxine by 25mcg. This was despite no signs of hyperthyroidism – resting heartbeat was 55bpm and blood pressure 120/80. Went obvious hypothyroidal after 2 months. This was only resolved by persuading doctor to return to 200mcg. Would this class as malpractice?
    Have since had a full panel done in Bulgaria. Two Bulgarian endocrinologists also decided results showed overdosing, and ignored FT3 being mid-range. Recommended reducing Levothyroxine by 50mcg, despite evidence from previous 25mcg reduction. Are these medics mad, or am I? How many patients’ lives are they ruining?

  • C Ring
    March 10, 2022 at 7:35 pm

    Very new to all this and have found your site informative and have ordered the book. Looking back I’ve been ill for over 20 years but only now because of high TSH have I been put on Levo. The complexity and variations are mind boggling to a newbie. Latterly I’ve been treated for arthritic flare up and muscle pain, IBS and reflux. All contributed to thyroid problems. Asked doctor for blood work out of desperation and have now got a diagnosis that makes sense. Looking forward to feeling better and now I have info that supports my foggy brain and can move forward.

  • Linda Bazuk
    April 7, 2021 at 2:06 pm

    H i Rachel, I just love the information you have offered. I am from Winnipeg, Canada. Have you ever heard of Jodi Knapp? She is American and offers a plan to completely eliminate Hypothyroidism. It costs only $49.00 and I am thinking about going for it. Do you have any comments or opinions about it? Please reply, I think you are such a good mentor. Best regards, Linda Bazuk.

    • Rachel Hill
      April 11, 2021 at 9:32 am

      Hi Linda, I haven’t heard of this before but would be very cautious.

  • Eloise
    April 7, 2019 at 7:58 pm

    Thanks for the terrific post


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