To Your Good Health: Hot flashes persist well past menopause and thyroidectomy

I am 81 and had a thyroidectomy in 2017. My whole thyroid gland was removed. I also had a little bit of cancer. I have started to get hot flashes again. I had originally been on thyroid medicine before and after surgery. Then I was put on levothyroxine and decided to try NP Thyroid. I was doing better on NP Thyroid, then started getting the hot flashes again. At this point, for several reasons, I would rather stay on NP Thyroid for the time being. I was wondering if there is anything I can take for hot flashes? Years ago, in my 50s, I took estrogen, which helped, but this is a different time. I have spoken with other people who are also having hot flashes again.

Hot flashes are common — about 75% of women in North America will experience them around the time of menopause.

It’s not uncommon for hot flashes to go away, then return, but I personally haven’t seen them recur after 30 or so years. I’d be concerned that there may be another cause for them, which brings me to your thyroid.

Elevated levels of thyroid hormone can cause sensations very similar to hot flashes. One reason that I, along with most endocrinologists, recommend against products like NP Thyroid is because most of those products come from pigs.

There are two thyroid hormones: thyroxine, or T4, and triiodothyronine, or T3. Humans have a different ratio of T3 and T4 than pigs do, with T4 getting converted into the active form, T3.

T3 is then quickly broken down, so if it’s used, it needs to be dosed twice daily. As a result, if a person takes NP Thyroid, their thyroid levels are too high during one part of the day and too low during another.

This isn’t good for anyone; the “high times” not only cause hot flashes, but also predispose people to atrial fibrillation.

But it’s particularly a problem in a person with a history of thyroid cancer, where we want the thyroid-stimulating hormone — TSH, the hormone in the pituitary gland that regulates the activity of the thyroid gland — to be on the lower side.

If the thyroid blood levels get low in the afternoon or evening when the T3 in NP Thyroid is gone, that can theoretically increase the risk of cancer recurrence as the TSH rises in response. So, in my opinion, you should be on levothyroxine, not NP Thyroid.

I do have a handful of patients who take levothyroxine and also take T3 twice daily. Some people are unable to convert T4 to T3 efficiently.

Estrogen is the most effective treatment for hot flashes, but it increases the risk of heart disease when used by women more than 10 years away from menopause. I don’t normally prescribe it to a woman in her 80s.

However, there is a new medication called fezolinetant, or Veozah, which is highly effective and reduced hot flashes by 93% in a trial. My only patient on it so far has reported 100% cessation of her hot flashes.

There are other rare causes of hot flashes, including tumors that secrete substances, such as carcinoid tumors, and tumors that secrete adrenalin-like hormones, pheochromocytomas.