Connect
Anastrozole's effect on TSH Thyroid level ???
I had my thyroid removed almost 5o years ago and my TSH levels have ranged from .550 mU/l to a high of 1.350 mU/l . Several weeks after I started taking the Anastrozole my TSH level was 2.97 mU/l which is more than twice the highest thyroid level I have had. My dosage has never changed. I can't help but wonder if the estrogen lowering drug has also raised my TSH level. I was just wondering if this has happened to any of you. Thanks Katrina123
Like
Helpful
HugInterested in more discussions like this? Go to the Breast Cancer Support Group.
Connect
Hi @katrina123, the FDA product monograph states (page 7) https://www.accessdata.fda.gov/drugsatfda_docs/label/2005/020541s016lbl.pdf
"In multiple daily dosing trials with 5 and 10 mg, thyroid stimulating hormone (TSH) was measured; there was no increase in TSH during the administration of ARIMIDEX (anastrozole). ARIMIDEX does not possess direct progestogenic, androgenic, or estrogenic activity in animals, but does perturb the circulating levels of progesterone, androgens, and estrogens."
I'm tagging fellow members @dorisena @shelleyc @kathyomaha55 and @remi, who have experience with breast cancer and thryoid issues.
Katrina, as you know, everyone is different, and I would talk to your oncologist and pharmacist about possible drug interactions and what adjustments might have to be made for you. Are you taking Synthroid (levothyroxine) since having your thyroid removed?
-
Like -
Helpful -
Hug
1 ReactionI have not had my thyroid removed. But I was taking levothyroxine for over 5 years before I had IDC. I took anastrozole for 12 months then switched to exemestane last November, neither drug effected my thyroid levels. I currently take 88 mcg daily for my thyroid. I have it tested yearly. Good luck and yes discuss it with both doctors. In 2016 I had trouble getting my dosage right, they had to increase it - but you have to take the new dose for 90 days before they know if it worked at that dosage. They changed my dosage 3 times that year. It was frustrating. Long before I had BC - so it may be completely unrelated.
-
Like -
Helpful -
Hug
2 Reactions@katrina123 Hi, Katrina... I'm going to take a shot in the dark here. I know that some of us worry about taking anastrozole and suffering from hair thinning, and then start taking Biotin in large doses hoping to counteract that. Biotin does help... it also leads to falsely high thyroid test levels. Many of us know to go off Biotin a few days before a thyroid test. By any chance are you supplementing with Biotin?
-
Like -
Helpful -
Hug
4 ReactionsHi, I can’t answer because I don’t take synthroid (levothroxine) or anastrozole, I don’t have a thyroid but all of the synthetic meds they tried on me I had reactions so I’m taking GTA Forte II for thyroid and numbers have been great for a few years now.
They didn’t even try starting me on anastrozole until I had breast cancer, as I said tried I’m not taking anything because as it turned out I’m allergic to something in that med. they tried one other and same thing.
-
Like -
Helpful -
Hug
1 ReactionI was on Anastrozole for over a month and had stomach problems so switched to exemestane and have been taking this for one month. No stomach issues so far, but at my yearly physical my TSH was low. Was taking synthroid for 30 years at 88mcg. My primary care physician changed the dosage to 75mcg and will retest blood and see me in two months.
-
Like -
Helpful -
Hug
2 ReactionsThank you for the information. I will add this question to my list for my next oncology visit.
Good to know. Thanks
Did your doctor give you any explanation for the change?
Yes I have taken the same amount of thyroid medication for almost 50 years.
No she didn't. I hope the lower dose straightens it out. I have been through chemotherapy, radiation, and now infusions of herceptin along with the exemestane so there could be several reasons!