Thyroid UK
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Slow Heart Rate and Low Oxygen Saturation

Hi friends ... I wonder if slow heart rate and low oxygen saturation are symptoms of hypothyroid? My oxygen saturation is always around 94% and falls to 80s% sometimes during sleep. My heart rate at many times during rest time will fall to 50s bpm and will feel short of breath and during sleep will go below 50 bpm causing me to wake up with adrenaline surges!


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My first reaction reading your post was to question why you are checking your blood saturation levels, this is a little unusual unless you have other health issues and have been instructed to do so by a doctor.

An underactive thyroid can certainly cause a slow pulse rate, and it is not uncommon for blood cell counts to be affected too, which in turn can lead to poor blood saturation levels. Your doctor can carry out a simple blood test to check your thyroid levels, and based on your blood saturation levels will likely carry out other blood tests at the same time to check cell counts.


No other conditions but people with hypothyroid are expected to go through many exams before they find out about thyroid. I have been asked to stay in the hospital to do a fasting blood sugar test and they do a routine check of blood sugar, oxygen pulse ... every a few hours. I'm taking T4 since July last year and little bit improving.

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Oxygen saturation levels record the percentage saturation levels of oxygen carried by the haemoglobin, they do not factor in the level of the haemoglobin. The saturation level is a good indicator of oxygen uptake across the alveolar membrane. It is perfectly possible to have a high saturation level but due to anaemia still be hypoxia at cellular level due to shortage of the haemoglobin to transport the oxygen molecules.

A low or falling saturation level at night is more indicative of a breathing problem. It can be something obvious like obstruction eg snoring, or something more complicated. Either way it needs further investigation. Low saturation at night can lead to increased chronic fatigue, falling asleep during the day and more worryingly long term damage to organs due to chronic shortage of oxygen.

I hope you manage to get to the bottom of the problem.


Thank you, yes my hemoglobin is border line or slightly below. You didn't talk about the slow heart rate! Isn't it possible that oxygen issue is caused by poor circulation?


Pulse oximetry the recording of oxygen saturation so need a strong enough pulse pressure for a reliable reading. Therefore as long as your blood pressure is adequate to produce a pulse the heart rate in immaterial to the saturation. if your blood pressure is low or the tissues particularly swollen the machine will not produce a reliable reading. The gold standard to assess oxygenation is an arterial blood gas, a blood sample taken normally from the radial artery in the wrist. This is then compared to the saturation recorded on the machine.

Hope that helps. Your slow heart rate may well be connected to hypothyroidism or in obstructive sleep apnoea secondary to low oxygen saturations.

I hope you get answers soon and regain your health.


Hi everyone, I only found this as I searched for my diagnosis 'Central Alveolar Hypoventilation'! I had a TBI (traumatic brain injury) closed in 1989 from a riding accident and was in a coma for four days. Since then I have Sjogrens Syndrome and was having to sleep all the time, had to stop working and driving, fell into debt and depression... After a decade I changed GP practice and my new GP listened to what I was describing and referred me to a Respiratory Consultant. It turned out that he had started out in Neurology but switched when he became frustrated by how little they actually know about the brain!

Anyway, after all the mega-expensive MRI scans (nad) he simply sent me home with a little wrist oximeter which recorded pulse and blood oxygen over 24 hours. I have since purchased one of my own on Amazon for £40! It showed that my blood O2 was dropping below 90 whilst I was asleep and he put me on oxygen - I have a machine at home and cylinders for when I go out. It is likely that my head injury - the crack on my helmet locates it as centre lower back - damaged the area of the brain that controls respiration...

Anyway when blood O2 falls below 90 brain cells die so it is not good news. I am now suffering memory problems and other neurological deficits most likely from all those years not breathing enough. I do not experience any sense of breathlessness or suffocation - I don't even yawn! Rather my brain demands that I sleep (not as in narcolepsy I do decide).

So it is something to take seriously and get referred to a Respiratory Consultant as it is a commonly undetected and untreated problem that can occur for a variety of reasons and needs an expert assessment. All the best!


Hi Caroline

Excellent reply and wonderful that you problem was dealt with. I am 68 and believe I have similar problem since I was 11 or 12 years old. . Not sure of cause as 4 issues happened which may have a part. Severe emotional trauma, fell on ice banging my head, got live polio oral vaccine and working backwards seem to have chronic infections of bartonella henselae, Q fever, helicobacter pylori cag A pod and others. Developed severe fatigue food intolerances and always v cold. Was diagnosed with low TSH and free T 3 5 years ago.

Recently also low acth and will get pituitary MRI

However my low oxygen sats are most frightening.

Was Refered to respiratory consultant who only tested for asthma and would not speak directly to me so presume will have to try another consultant. I will go on amazon and get this wrist watch to measure oxygen sats and BPM overnight. Great idea. Like you Caroline I now have macular degeneration, cataracts, homes adies pupil, acne Rosacea in eye, and recently diastolic dysfunction, cortical atheist, carotid atherosclerosis poor memory confusion all of which are probably due to low oxygen sats



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