No she has not been diagnosed with hypothyroidism. Her biggest complaint is she is extremely fatigued. Our mother was recently diagnosed hypo and our older sister and our grandmother are on hypo medication so I encouraged her to get tested.
I'm a little confused about the ranges. Are you outside of the US? Can you add the units of measurement? Some labs have wider ranges than others, so it's not always accurate to give a percentage of the range as a definition of hypothyroidism. There will be an optimal range but that's not necessarily the upper third in all cases where the upper limit goes quite high.
I used the word "range" a lot there!
Some labs have wider ranges than others, so it's not always accurate to give a percentage of the range as a definition of hypothyroidism. There will be an optimal range but that's not necessarily the upper third in all cases where the upper limit goes quite high.
I used the word "range" a lot there!
No, not really. The test's result (your blood level) must be compared with the reference range that was used for that specific test. The percentage will be accurate when that result and ref range are used to calculate it. It would not be accurate at all to compare the blood result with some other lab's range.
Since you mention a strong family history, I would be much more inclined to think your sister's low FT4 and small TPO titer is an early indication of impending trouble. She can try getting a diagnosis now, but I have to warn you that it will be difficult. If she can find a doctor who's well-versed in prescribing natural thyroid med or Cytomel, she may have a better chance getting treated now. Some people have found such doctors by asking pharmacists who sends them natural thyroid scripts.
__________________ "We can complain because rose bushes have thorns, or rejoice because thorn bushes have roses." Abraham Lincoln
Midwest- each lab creates its own ranges. For example, though my lab has a range for FT3 that goes down to 1.8, the range for quest labs starts at 2.3. Just as there are adjustments in lab range for TSH from 0.5-5.5 to 0.3-3, you may be at the top of the range with one lab and mid-range with another.
Diagnostic Automotion has a range for FT3 that is 140-420 pg/dL, yet the NACB advises a higher reference range of 200-500 pg/dL. Since each lab may use different "test populations," sometimes there are discrepancies. I wouldn't be below range in FT3 at my local lab but I would be if I sent my blood work into Quest Labs. Dr. Ken Woliner gives a good explanation of this.
I think we're sort of saying the same thing. However, if every lab used the same diagnostic method, the same units and the same "healthy" population control, there would still be different lab ranges. I don't know how they determine the cutoff point and why one lab will have an FT3 range of 1.8-4.2 pg/mL and another 2-6. However, given the fact that they use the same units, if you submitted the same blood sample to both labs, you might be at the top of the range in one and over the range in the other. In this case, she might be closer to the 50th percentile had she had her blood tested at my lab but since the lab range goes so high, she is closer to the bottom. I'm merely trying to determine if she is using the same units of measurement as most American labs.
Either way, the lab numbers look strange to me, I've never seen an FT4 range go up to 4.9. That's why I'm wondering if the units are different. And the FT3 range looks more like the range for TT3 in the US.
Perhaps what you are not understanding is that different labs use different "kits" for testing. (It's a chemistry thing that I can't really explain. ).
Each lab's "kit" will have different ranges that are unique to their method of testing.
As Midwest said, the percentile result and range will be individual to each lab. Sending the same blood sample to 2 different labs will give you an accurate percentile result based on their range only.
I hope this helps you understand why lab ranges differ so much and also why we must have the ranges along with results to interpret them correctly.
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