ppt or hashimoto?

[sarahvan]

When my son was 6 months old two weeks ago, my blood test result was the following,
TSH 127.6   FT4 4.3   Antithyroid Peroxidase AB >6500 U/ml (normal range  0-60) Microsomal AB  8730 IU/ML (normal range <35)
Then I started to take synthroid from 50mcg for 3 days, 75mcg for 3 days, to 100mcg for the last week.
My new test result shows that TSH 27.5 FT4 12.6 (within range 10.5-20).

It seems that my hormone level is bouncing up and down. My doctor said this is Hashimoto and suggested me to increase synthroid to 125mcg. I am wondering whether it is possible that I am having postpartum thyroiditis only. The first reason is that I am not having some typical symptoms such as sensitivity to cold and constipation. Secondly, the medicine took effect so fast so that I guess my thyroid is still working to some extent. Thirdly, I had hyper when I was a teenager for a year so that the hormone level is not stable, esp after I gave birth to my son. Of course, I could be wrong about these and would appreciate for your reply.

[AmandaG]

So how do you know the difference?  My endo diagnosed me with PPT, but I'm skeptical because my daughter was born 12 weeks early and I lost 7 lbs during the last month of my pregnancy which makes me wonder if it was something that I already had or something that manifested itself DURING my pregnancy rather than after.

[Mark Lupo, M.D.]

You likely have chronic thyroiditis (hashimotos), but given the rapid decrease in TSH with apparently only 2 weeks of synthroid, there is a chance your thyroid is recovering and this is transient post-partum thyroiditis.  Would be reluctant to jump to 125mcg given the rapid decline in TSH -- would consider staying on 100mcg for another 6 weeks and rechecking -- if TSH still high then increase the dose and it's likely permanent, if normal, then consider weaning off synthroid and re-evaluating.  If you are planning more pregnancies in the near future, stay on synthroid to keep thyroid regulated until done with reproduction, then try to wean off.