 [ Symptoms ] i am on 300 mcg of synthroid is there other things that need to be tested besides my thyroid just dx with hashismoto is [ Disease ] hashimoto is is a thyroid disease so if your health care provider prescribed synthroid for it then that is the appropriate treatment according to this webmd article hashimoto is is an inherited thyroid disease the disease affects your thyroid gland is ability to produce thyroid hormone which is essential for proper functioning because you were recently diagnosed you should understand it can take a period of time to regulate your thyroid gland appropriately it takes about 3 months to assess the effectiveness of any dose of thyroid medication so you might expect changes to your dosage over the next year or more your health care provider probably will monitor this closely in order to determine the appropriate dose of thyroid hormone for you in addition your thyroid dose may change many times over the course of your lifetime if you have questions about this do not hesitate to discuss it with your primary care provider or endocrinologist the good news is that thyroid problems usually are not life threatening with proper treatment you can expect to live a normal life best wishes to you