Welcome to Connect @romanjay26. You’ve been taking Anagrelide and/or hydroxides for 23 years for your ET. Those are very standard medications for treating the over production of platelets. Were you switched from either of those medications to the Peg-interferon to control the platelets instead?
Were the treatments no longer working for you? Is this when your thyroid started to change or have you had thyroid issues for a number of years?

I’m a little confused by what you mean about increasing another medication from 125mg to 200mg daily. Is this a thyroid medication that you’re taking as well as the Pegasys interferon?
According to information on the Pagasys site, it states that: “ Pegasys (peginterferon alfa-2a) can cause or worsen diabetes and thyroid problems.”. So this may be why your thyroid levels may be ‘deranged’. That’s such an interesting term…one not used in the States. I’m not sure what that really means but sounds as though it warrants investigation!

Losing weight so abruptly, with blood loss and bowel inflammation must be very worrisome for you. Have you brought these symptoms to the attention of your oncologist or primary care physician?