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What causes low TSH level in blood?

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Posted on Mon, 18 May 2015
Question: I take levothyroxine for low thyroid. On my yearly tsh test I went from 3.92 to 1.35 the next year. Do I need more levo or less? My dr says its fine, but I am always cold,loosing a lot of hair, tired a lot. This is a new dr for me. I am woman 72years old
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Answered by Dr. Saumya Mittal (19 minutes later)
Brief Answer:
same dose needed

Detailed Answer:
Hi
I am Dr Mittal.
I have read your query.
I think I would be able to help you.
The dose of the thyroid medicines you are taking seems to be adequate. I will not suggest changing the dose.
As for your other problems, it's possible that the loss of subcutaneous fat that is always seen in elderly is causing the symptoms.

Unfortunately, there is no good treatment for that.

I have tried to make it as simple as possible. I hope that the information helps you. Please feel free to contact us for more information. Best of luck. Dr Mittal
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
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Follow up: Dr. Saumya Mittal (1 hour later)
My weight is 311. By sub cue, you mean just under the skin, right, that applies to my hands only, everything else is well padded...lol.

My tsh was 3.92 in 2012,13,14 then 1.35 in XXXXXXX of 2015. I thought levothyroxine was suppose to raise the level of the missing or lowered thyroid hormone in my body. This sounds like the levo is not doing that. Why wouldn't upping my dose raise the tsh level........I felt fine at the 3.92 level and now feel like crap. thanks
doctor
Answered by Dr. Saumya Mittal (1 hour later)
Brief Answer:
Explained the physiology

Detailed Answer:
Thanks for your response
You have to understand thyroid hormones to get the answer I gave.
TSH rises when the thyroid hormones T3 and T4 are low.
It tries to make the thyroid hormones.
When thyroid hormones are available, it has not got to make anything. So it becomes low.
So it should become low.
T3 and T4 become high.
For monitoring, we use only TSH.

As for fat, it does not matter if you are on the heavier side.
The generalized coat of fat under the skin becomes reduced.
Thats what I meant by subcutaneous fat pad.
One may be very fat, but skin fat coat reduces with age.
So it causes feeling of cold as well as loss of hair, skin wrinkles etc.

As per me, your thyroid levels are good.
Continue the medicine as it is.
Best of luck.
Dr Mittal
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
doctor
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Follow up: Dr. Saumya Mittal (10 hours later)
Dr Mittal, So if I understand your answer, in the years when my TSH was 3.92, that was my thyroid not doing its job and the levo was compensating. Now for some reason my thyroid has begun producing the hormone again in enough of an amount to lower the amount that the levo has to cause to be produced. So the levo some how sees the t3 and t4 are high and does nothing or produces very little additional hormone, just enough to give me what I need. What would cause my thyroid to begin working again?

I just noticed your specialty is diabetes and I didn't mention that I was diagnosed as diabetic type 2 just last XXXXXXX when I was having the tiredness and hair loss and my Dr found my A1c at 9 and by december of last year it had gone down to 6 and I am on 500mg ER of metformin daily. Could this affect my thyroid levels. My morning fasting levels are usually between 111 and 130 if that helps. Thanks
doctor
Answered by Dr. Saumya Mittal (4 hours later)
Brief Answer:
explained

Detailed Answer:
It's more likely that the thyroid replacement therapy is working better and thus may be related to your weight loss probably. In diabetes, there is always some weight loss. This would have reduced the need of thyroid.
However, I would not suggest that you reduce the dose of thyroid replacement therapy.
I hope that the information helps you. Please feel free to contact us for more information. Best of luck. Dr Mittal
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
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Dr. Saumya Mittal

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What causes low TSH level in blood?

Brief Answer: same dose needed Detailed Answer: Hi I am Dr Mittal. I have read your query. I think I would be able to help you. The dose of the thyroid medicines you are taking seems to be adequate. I will not suggest changing the dose. As for your other problems, it's possible that the loss of subcutaneous fat that is always seen in elderly is causing the symptoms. Unfortunately, there is no good treatment for that. I have tried to make it as simple as possible. I hope that the information helps you. Please feel free to contact us for more information. Best of luck. Dr Mittal