How low does BBT have to be to be an indicator of hypothyroidism? - Mothering Forums

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#1 of 4 Old 03-03-2012, 07:23 AM - Thread Starter
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I have been reading a lot on various postings and in books that low BBT can indicate a thyroid problem.  How low is too low?  Before O my temps are consistently 96.8-97.2, then jump up to 87.6-97.8 after O.  I have only gotten to 98.0 2-3 times in 5 months of charting.  I have an appt with my MD on Monday to talk about having my progesterone tested because my LP is only 9 days and I want to bring this up as well.  I am not sure how open to testing it she will be so I want to have all my facts straight going into it.  We are in our 7th month of trying and based on my charts I think something is up, I just want to know what.  I would love any advice/input people have!


I am 29, married to DH for 2 years with 2 crazy pups and, after what feels like a huge wait (shorter than many, longer than wanted!), we are expecting our first little one April


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#2 of 4 Old 03-03-2012, 08:07 AM
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I'm no doctor and don't have personal experience with hypothyroidism, but I don't think there is any specific cut off for what would be considered hypothyroidism.  I think that pre-O temps in the high 96's and LP temps in the high 97's is normal for a lot of women.  But I also think that you're right to look into it just in case!  With your short LP, it's likely you're dealing with low progesterone and dealing with that might bring all your temps up a bit. 


It has been my experience that often you need to be firm with care providers and simply tell them what you want to do.  Politely, but firmly you could say, "we have been TTC for ___ months now and through charting my fertile signs I've noticed a couple of things... ________ and ________ and I would like _______ and _______ tested."  Push for 7dpo progesterone testing as well- not just CD3.

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#3 of 4 Old 03-03-2012, 10:42 AM
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I have hypothyroidism and my pre-O temps are in the low to mid 96's and my highs are in the mid 97s.


On another board, thanks to a person named metalchevy, she posted a list of tests to have done.  I am looking into have more of these done, although I have only had Free T4 and TSH test.  I had the TSH test many times before and told I was "normal" but when they tested the free T4, the doctor actually used both my symptoms and that testing value to diagnose hypothyroidism.  My dentist, a few weeks later, agreed with the diagnosis and said my scalloped tongue, thin weak fingernails, and eye brows that are thin in the outer third agree with the hypothyroid diagnosis.  Check out this page for some more information:


Determining hypothyroid is an art and a science.  If you have other symptoms of hypothyroid like listed in the web page above, keep working with a doctor until you find the right fix for you.  What works for one hypothyroid person doesn't work for all since our bodies all behave differently.



So onto the tests.  Thanks to a person named metalchevy on another forum who said first test,

Free T4 (very, very important it is free not total. Total = useless)
Free T3 (ideally) or Total T3 (acceptable)

If you haven't had them before:

Thyroid peroxidase antibody (TPOAb)
Thyroglobulin antibody (TGAb)

The two above will tell you whether you are dealing with autoimmune hypothyroid (Hashi's) or not. I think its good to get that DX because it can help you down the road to fight for better/more frequent retests and care. At least that has been my experience. There are also some studies out there that suggest a high TPOAb may correlate to increased m/c (even more than the just general all around increase in m/c risk we all have as Hashi's gals).

Another test that isn't absolutely necessary, but could also be considered:

Reverse T3 (done when Free T3 taken)

This test can reveal whether you have conversion issues. T4 and T3 are the actual active thyroid hormones that impact how we feel. We get 80% of our T3 by the conversion of T4 to T3, which happens when the T4 drops an iodine atom to become T3. T3 is much more potent than T4. Sooo... if you body is handling this conversion process appropriately, your still gonna feel bad and suffer the ill effects of hypothyroidism even if your TSH and Free T4 are "normal."

Other biggies I would HIGHLY recommend:

Vit D3
Vit B12
Ferritin, TIBC, Serum Iron
Complete metabolic panel (magnesium, potassium, etc.)

I recommend the above because most of us have serious absorption issues that cause us to be insufficient in many of the things listed above. I felt 1,000 times better when I got on Synthroid, but that list little bit of true healing only kicked in when we found out how deficient I was in Vit D and B12 and started supplementing both with simple OTC vitamins.

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#4 of 4 Old 03-05-2012, 02:49 PM - Thread Starter
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Thanks for the info.  For now we are going to test thyroid, progesterone, and a fasting glucose and insulin.  we will see what those show and go from there, but I am hopeful we will get things figured out!


I am 29, married to DH for 2 years with 2 crazy pups and, after what feels like a huge wait (shorter than many, longer than wanted!), we are expecting our first little one April


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