My Heart Rate Spikes on Synthroid
Over the past 8 months I have noticed abnormal shortness of breath and 'spiking' heart rate while exerting myself or exercising. I was on dessicated thyroid for Hashimoto's and moved over to Synthroid 100mcg. I have logged my exercise tolerance daily for the past several years. I assumed that since my thyroid labs were in the normal range (FT3 , FT4 and TSH), that there was need to increase my dosages. Went from 100 mcg to 125mcg. Shortness of breath was really bad, and heart rate would 'spike' 40 bpm just to go from a sitting to a standing position. I dropped back to 100mcg, and over past week dropped down further to 70mcg (by breaking pills in quarters). Over past week I noticed a significant drop in my heart rate spikes by monitoring all physical activity with a watch heart rate monitor and a finger pulse oxyimeter. ... more »
Over the past 8 months I have noticed abnormal shortness of breath and 'spiking' heart rate while exerting myself or exercising. I was on dessicated thyroid for Hashimoto's and moved over to Synthroid 100mcg. I have logged my exercise tolerance daily for the past several years. I assumed that since my thyroid labs were in the normal range (FT3 , FT4 and TSH), that there was need to increase my dosages. Went from 100 mcg to 125mcg. Shortness of breath was really bad, and heart rate would 'spike' 40 bpm just to go from a sitting to a standing position. I dropped back to 100mcg, and over past week dropped down further to 70mcg (by breaking pills in quarters). Over past week I noticed a significant drop in my heart rate spikes by monitoring all physical activity with a watch heart rate monitor and a finger pulse oxyimeter.
At least in my case it appears that the thyroid hormone is causing my heart rate to have an exaggerated response to exertion, even though my labs are all in the normal ranges. Other info: Male, 48, 6'3, 200lbs, athletic, non-smoker, workout 6+ hours week. Also have osteopenia, peripheral neuropathy (unknown cause), neutropenia, low hematocrit.
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