4 doctors weighed in:

Low T3 (liothyronine) uptake (21%), Normal TSH (3.190), normal T4 (9.4), normal free thyroxine index (2.0). Also low BUN/creatine ratio (7). Is this normal?

4 doctors weighed in
Dr. Richard Zimon
Internal Medicine
1 doctor agrees

In brief: YES

T-3 Uptake not a reliable test.
...the rest of your thyroid tests are normal and your kidney function is as well!

In brief: YES

T-3 Uptake not a reliable test.
...the rest of your thyroid tests are normal and your kidney function is as well!
Dr. Richard Zimon
Dr. Richard Zimon
Thank
2 comments
Dr. Ira Katz
Agree, T3-uptake, is not even actually a thyroid test, but used to calculate T4 (much more accurately) under certain circumstances!
Dr. Ira Katz
Except under certain rare circumstances a low BUN/Cr ratio is not something clinically significant. Generally, a high ratio is what is being looked for and why the test is done.
Dr. Ira Katz
Internal Medicine - Endocrinology
1 doctor agrees

In brief: Normal!

The T3-uptake is one of the most misunderstood tests in thyroidology (real word).
It does not actually measure any thyroid hormone or function! The T3-U is used to calculate a more accurate T4 when maybe on certain medications, be pregnant, menstrual cycle time...all of which may effect the T4 level. If used your T4 should say FTI, T7 or have some other disclaimer. You can pretty much ignore it.

In brief: Normal!

The T3-uptake is one of the most misunderstood tests in thyroidology (real word).
It does not actually measure any thyroid hormone or function! The T3-U is used to calculate a more accurate T4 when maybe on certain medications, be pregnant, menstrual cycle time...all of which may effect the T4 level. If used your T4 should say FTI, T7 or have some other disclaimer. You can pretty much ignore it.
Dr. Ira Katz
Dr. Ira Katz
Thank
2 comments
Dr. Ira Katz
A lot can be gained from the T3-uptake, such as your labs were likely done late in your cycle or you may have irregular cycles, which is why they were ordered.
Dr. Ira Katz
Except under certain rare circumstances a low BUN/Cr ratio is not something clinically significant. Generally, a high ratio is what is being looked for and why the test is done.
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