What Causes Irregular Heartbeats While On Synthroid?

Posted on Tue, 13 Jan 2015

Medically reviewed by Ask A Doctor - 24x7 Medical Review Team

Mon, 12 Jan 2015 Answered on

Tue, 10 Feb 2015 Last reviewed on

Question : I am a 56 year old woman. I have been taking synthroid (75mcg) for about 4 months. Recently, I started experiencing an irregular heartbeat - random skipping of beats. I had a physical with my cardiologist in October, all is well. This has happened now 7 out of the last 11 days. In the beginning, it was only in the late afternoon/early evening. This past Friday, when it started around lunchtime, I went to my cardiologist, he did a 6 second EKG and all was normal. He sent me home with a portable EKG for 24 hours and I felt nothing. Shortly after returning to the dr's and having it removed, the irregularity started again and has been off and on ever since. This is freaking me out. Could it be related to my thyroid meds?

Answered by Dr. Noble Zachariah (-4 hours later)

Brief Answer:
Excess of thyroid medication can be a cause

Detailed Answer:
Hello,
Welcome to HCM and thanks for your query.
Excess of thyroid medication can produce irregular heart beat and palpitations. Anxiety is another possible cause.
Please check your TSH and FT4 and FT3 values.

Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar