Question About Thyroid Tests and IVIG

On August 1, my thyroid peroxidase (TPO) came back high at 38, with 34 being high normal. I posted about it then, and it was mentioned the IVIG I have done monthly could be causing transient positives. My thyroid globulin was extremely high at 10, with 0.9 high normal, so 10 times above high normal.

With that ind mind, I held off longer on the IVIG so I could see if the numbers would come down. So on Sept. 29, after waiting more than a month without IVIG, the TPO came down to 32 (normal) and the thyroglobulin was down to 5.7.

Yesterday I had the same two tests done as I waited 38 days without IVIG. This time, the TPO is 20 and the thyroglobulin is still high, but down to 2.7.

T4 is normal.

Does that look like the high numbers were due to the IVIG? It has a long half life. Even waiting 38 days wasn't going to get it all out of system.

I have never dealt much with thyroid issues, except low T3. But T4 and other tests were all normal before. Also, my ANA was negative yesterday after a positive a few months ago.

i agree - it seems like the levels are gradually dropping over time - exactly as you would expect if they were from the exogenous IVIG gradually reducing in your system.

I took the liberty of plotting the points so they can be displayed on a chart
I find this a very useful way of analysing trends

VIEW IMAGE

looks like it may take 60-80 days to fully come out of your system - but from the above you can see its very well correlated with the time from last IVIG - so i would not be too concerned about actual thyroid auto-immunity being present - which is very good news!

all the best!

Thanks for your thoughts and great help. I wouldn’t think numbers would go down, as Rainy mentioned


Garzie -,Tells a lot about you taking the time to do the chari. Thank you.

Astroman- I know you are the thyroid king. Figured you’d jump in.