Hi, dear I have gone through your question. I can understand your concern. First of all your low thyroid and swollen lymphnode doesn t have any relation. There ate many causes of swollen lymphnode. Most common causes are reactive lymphnode and tuberculosis. Other are rare like lymphoma. If you don t have other features like liver and spleen enlargement then chances of cancer is very very low. You should go for fine needle aspiration cytology to search for the cause. Then take treatment accordingly. Hope I have answered your question, if you have doubt then I will be happy to answer. Thanks for using health care magic. Wish you a very good health.