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Thyroid UK
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Confusing lab results

Hi all- complex question- really discouraged and welcoming input...I recently had lab work done and it came back with a very low tsh (undetectable at 0.0019), a low total t3, and a free t4 that was in the normal range, on the higher side of normal range. In addition, I have been on thyroxine medication for the past 6 years...it was not given specifically for a "hypothyroid diagnosis" but to help alleviate symptoms typical of hypothyroidism and to counteract the effects of an antidepressant/mood stabilizer. I was diagnosed 3 years ago with adrenal fatigue and things had been much better since then...however, several months ago I became very lethargic, spacey, and very easily fatigued. I am normally very active but now I am so spaced out that I am having a hard time getting anything done. I had attributed this to side effects of the mood stabilizer because the fatigue did get much worse a few weeks after being on it.

The naturopathic doctor who original ordered the test and picked up that something hormonal was going on explained that my thyroid is producing but my pituitary is not converting it because it thinks there is enough. So she is suggesting secondary hypothyroidism and prescribed me thyroxine as well as pituitrophin.

my psychiatrist disagrees and is concerned and urging me to see an endocrinologist (I have an appointment in a week.) He doesn't seem to think it is a pathway issue and is saying that this is abnormal.

Has anyone experienced anything similar to this? I am very frustrated with the doctors disagreeing and I am so tired and have no energy.... I've also gained weight due to being so sedentary, despite my efforts of eating very healthy which is causing me to get sad/upset and frustrated with the lack of communication. I would like to make sure the endocrinologist tests for the right things and doesn't blow me off because I have been suffering for quite awhile now. Any advice is very appreciated!

11 Replies

Not an expert on these things but here are a few things. You obviously have a very complex situation here but could your results be explained by the T4 you are taking suppressing TSH production, normal TSH caused by taking thyroxine (did you stop taking your thyroxine before blood work done?) and do you have a T4 to T3 conversion problem resulting in low T3?. Low T3 (the active thyroid hormone) could cause many if the symptoms you describe, Make sure you stop thyroxine before the next blood test and I wonder if you need some T3 or a combined T4/T3 preparation such as NDT?


You could have stopped converting due to high t4 levels. Some people can't have their thyroid hormone levels at the high end of range without totally suppressing tsh. I am one of them. And you could have built up a resistance to the t4. All kinds of sscenarios possible, and a visit to an endo to rule out pituitary problem is definitely a good idea.


A visit to an endo to rule out pituitary problem is definitely a good idea...I agree with this entirely and wish you Luck ....something not right for sure ...


Yup, all this sounds about right. Taking the thyroxine suppresses the TSH, even though you don't have enough hormone to make you well, and your body can't convert it into the necessary T3.

But don't get hung-up on the low TSH. It is irrelevant. It is only relevant if it is high, but when it goes low or suppressed, it doesn't mean anything. The important tests are the FT4 and FT3.

Hope you have a good endo appt.

Hugs, Grey


I'm sorry but I have to totally disagree with you there, it is not irrelevant, a low/normal TSH is very important to take note of as a Low/Normal TSH and a Low/Normal Free T4 and Free T3 can indicate secondary hypothyroidism which can be signalling a Pituitary problem.

After years of being undiagnosed I'm having a Pituitary MRI next week for that exact reason.

The TSH isn't as accurate or fool proof as some Dr's will have you believe, if your pituitary is up the spout and the patient is suffering from symptoms then you can't rely on the TSH test if it's giving you a low or normal reading and it needs to be investigated further.

This is why it's so so important for doctors to look at the patients symptoms and not just rely on the test results, as the test results are as only as good as the Dr's interpreting them.


But she didn't say she had a low normal T4, she said it was highish normal. Therefore in her case the low TSH is irrelevant and I didn't want her fixating on it and worrying. That's all.

Besides, surely there you are talking about people that are not on any thyroid hormone replacement. Once you start THR, the link between the thyroid and the pituitary is broken and is no-longer reliable, and should not be used to dose by. That is what I mean by irrelevant. We all know that doctors should go by symptoms and just use the labs as a rough guide. Sorry if you misunderstood me.

Hugs, Grey

1 like

I know what you mean just what I read was open to interpretation, I just wanted to make clear anyone reading this the pitfalls of using TSH.

The problem is virtually every medical professional assumes the pituitary gland is functioning correctly with hypothyroidism hence there over reliance on a high TSH. They forget about secondary and even tertiary hypothyroidism.

All the best,




My thyroid issues come from my pituitary , had an mri scan 7 weeks ago to rule out a tumour , I don't have one but I have a shortage of fluid in that area since giving birth to my daughter 26 years ago.. My numbers are ok apart from a persistant low tsh 0.01 my adrenals are poor too because of the pituitary problem .. so far no treatment tho going back to see endo in 3 months. Sounds to me like your problems are pituitary related .Good Luck..


I went through a similar situation for two years, being misdiagnosed and given the wrong medication. They finally decided it was Graves Disease, then after two more years of drugs and remission and drugs, they removed my thyroid. Then it was another year or two of adjusting medication. Meanwhile, you feel like you are stepping on the brakes and the accelerator at the same time, and it is exhausting. I eventually changed to a vegan diet and my health improved dramatically. I am stuck with thyroid meds forever, but am now well. you can check out a healthy vegan diet by googling Dr John McDougall or Caldwell Esselstyn or Joel Fuhrman. At the very least, do yourself and your body a favor and try it for 30 days. Maybe you can get off the drug wheel. Good luck


I am inclined to agree with most of the other posts here that since you are on a T4 only med, it has suppressed the TSH but that the T3 is not being converted properly. Things to look for in conversion are low iron, B12, Vitamin D, and also adrenal function. The symptoms that you have are pretty consistent with low cellular T3 production. Have you taken your temps at all? How are your vitals?


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