Jen,
They should have done a full baseline thyroid test on you BEFORE you ever had radiation. Check with whoever was doing your blood work. Having thyroid problems after radiation is not uncommon. They checked mine very 3 months for years. I did not have a problem until the second cancer when they removed half my thyroid as part of my other surgery. It took a while to find the correct dosage but now no problems. You want your TSH to be as close to what it was before radiation as possible. Being 'in range' is not good enough as the range is fairly large. Your inability to gain weight may be related to your TSH level not being what is normal for you. The pills are tiny and seem to have no side effects. I get a full thyroid blood test every 6 months, every 3 if thre is a change in meds.

Take care,
Eileen


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Aug 1997 unknown primary, Stage III
mets to 1 lymph node in neck; rt ND, 36 XRT rad
Aug 2001 tiny tumor on larynx, Stage I total laryngectomy; left ND
June 5, 2010 dx early stage breast cancer
June 9, 2011 SCC 1.5 cm hypo pharynx, 70% P-16 positive, no mets, Stage I