For patients
Autonomic symptoms: the system you never think about
The autonomic nervous system runs blood pressure, heart rate, temperature, digestion, sweating, bladder and sexual function without asking you. When it drifts, the symptoms are scattered enough that they are usually attributed to something else.
What the autonomic nervous system does
It regulates the processes you do not consciously control: blood pressure, heart rate, body temperature, digestion, metabolism, fluid and electrolyte balance, sweating, urination, defecation and sexual response. It has two divisions — sympathetic and parasympathetic — and most organs are controlled predominantly by one of them, with the other providing the counterweight.
Almost every symptom below is the result of the counterweight failing rather than the system switching off.
The symptom list
Cardiovascular
- Lightheadedness or greying vision on standing
- Fainting
- Heart rate that will not rise with exercise
- Exercise intolerance out of proportion to fitness
- Palpitations
Digestive
- Feeling full after a few bites
- Nausea or vomiting after meals
- Heartburn and difficulty digesting food
- Constipation alternating with diarrhea
Everything else
- Sweat abnormalities — too much, too little, in the wrong place
- Bladder urgency, hesitancy or incomplete emptying
- Sexual difficulties
- Blurred vision and poor dark adaptation
- Fatigue and heat intolerance
Why it is so often missed
Each of those symptoms has an ordinary explanation available. Lightheadedness gets attributed to dehydration. Early fullness gets attributed to reflux. Fatigue gets attributed to age. Each attribution is reasonable on its own, and collectively they hide a single system that can be measured directly in twenty minutes.
How it is measured
Autonomic testing looks at heart rate and pulse waveform at rest and during standardized challenges — deep timed breathing, standing up, and a brief controlled exhale against resistance. Each challenge asks a specific branch of the system to respond, and the size and timing of the response is the measurement. Heart rate variability and the reflex tests describe the components.
What autonomic testing cannot tell you
It cannot tell you the cause. Diabetes, kidney disease, thyroid failure, hepatitis, Parkinson’s disease, medications and simple deconditioning all produce overlapping patterns. It also cannot distinguish, on its own, between a nerve problem and an artery problem — which is exactly why the vascular study is run in the same appointment. The treatments for those two are quite different, and telling them apart is the point of testing both.
If you are a clinician: the same subject written for the person ordering the test is at the full test description.
Talk to someone about testing
Tell us what you are trying to find out and we will explain which Measura assessments answer that question, what each one involves, and how the results are reviewed with a clinician.
4477 Woodson Rd, Suite 201, St. Louis, MO 63134. Monday to Friday, 9:00 a.m. to 5:00 p.m. Please do not send symptoms, diagnoses or images through a web form — a website form is not a secure medical channel. Call us with clinical detail.
Common questions
Is this the same as dysautonomia?
Dysautonomia is the umbrella term for autonomic dysfunction. Testing measures how the system behaves; naming the syndrome is a clinical judgment on top of that. What the numbers mean.
Could my medication be causing this?
Frequently, yes — beta-blockers, anticholinergics, antidepressants and bladder medications all affect these measurements. Never stop one to make a test look better. Preparation and medications.
I feel dizzy standing up. Is that autonomic?
It is one of the classic presentations and it is directly measurable. Dizziness and the risk of falling.
Does poor sleep affect the result?
Considerably. So does alcohol, caffeine and a hard training session the day before, which is why preparation instructions exist. Why the number moves.
Medically reviewed by Dr. Gurpreet Singh Padda, MD, MBA, MHP, medical director of Measura. Last reviewed .