(Updated on 7/1/24)
What Is OI?
Orthostatic Intolerance (OI) is a condition that affects over 97% of people with myalgic encephalomyelitis and chronic fatigue syndrome (ME/CFS) - in other words, almost all of us, though you may not even be aware of it, and it also occurs in many patients with fibromyalgia or Ehlers-Danlos Syndrome (EDS), or Lyme disease and other tick infections. OI is an umbrella term that means an inability to maintain a steady blood pressure (BP) and/or heart rate (HR) while upright and includes different conditions, including the two most common in ME/CFS patients: Postural Orthostatic Tachycardia Syndrome (POTS) and Neurally Mediated Hypotension (NMH). Both of these conditions exist outside of ME/CFS and are generally understood by some cardiologists and other medical professionals (though the term OI is used more often specifically in ME/CFS). Some people with ME/CFS have just one or the other, but many of us (including both of my sons and me) have both. And some patients have rarer types of OI conditions, where BP goes up or HR or BP jump up and down. It's all OI, an inability to hold blood pressure and/or heart rate steady while upright.
POTS occurs when your pulse rate goes way up when you are upright (standing or even sitting up). NMH occurs when your blood pressure drops while upright. Some people with severe POTS and/or NMH actually faint or feel dizzy or lightheaded, but for many of us with these conditions our "usual" symptoms just get worse and we feel sicker.
Why Does It Matter If I Have OI?
Even if you don't know you have OI, it is underlying many - sometimes most - of the symptoms you associate with ME/CFS (or with fibromyalgia or EDS or tick infections), including Post-exertional Malaise (PEM). It is a big part of what makes those with ME/CFS "crash" or worsen after too much exertion, and it makes all symptoms worse. The good news is that treating OI often results in improvements (sometimes dramatic ones) in all symptoms, allows you to be more active without crashing, and can greatly improve your quality of life.
Our Experiences Diagnosing OI
I read about OI during the early years of my own illness and shortly
after we realized that our oldest son probably had ME/CFS as well, but I
didn't think that either of us had OI. Neither of us had ever fainted
or even felt light-headed, so I assumed it didn't affect us. Besides,
both of us had normal blood pressure during routine office exams. I was
very wrong.
My son and I went to see Dr. David Bell,
one of the world's top pediatric specialists in ME/CFS, now retired, in
December 2003. During our visit, he officially diagnosed our son with
ME/CFS and confirmed my diagnosis (I'm lucky enough to have a family
doctor who recognizes and understands ME/CFS). Then, he told me about
OI. I told him I'd read about it but didn't think it applied to us. He
was almost certain it did and asked if he could test my son in his
office.
I was stunned by the OI test. Although a tilt table test is the formal method most often used by cardiologists for diagnosing both POTS and NMH, they can also be detected in a simple office test (which is quicker, far less costly, easier on the patient, and studies show may even be more accurate, since it mimics real-life conditions). He had my son lie down for 10 minutes, and a nurse took his resting blood pressure and heart rate. Then he asked him to stand up and stand perfectly still, leaning against a wall, without moving at all or even fidgeting or wriggling toes. The nurse took his blood pressure and heart rate every minute. Within less than 10 minutes, his feet turned purple (that's the blood pooling in lower extremities instead of circulating properly), he complained he was very hot (in western NY in late December!), and he started to feel sick. His blood pressure plunged, and his heart rate went way up. Dr. Bell ended the test after about 8 minutes; he said if they kept going, he would probably faint. He also said he wouldn't test me because I'd probably feel too sick to get the two of us home, but he was certain the results would be similar for me.
This is how OI often affects those of us with ME/CFS. Some people do feel dizzy or lightheaded (some even faint), but for many of us, being upright simply makes us sicker; OI worsens all of our symptoms. In fact, for many people, OI is behind most of our worst symptoms.
ME/CFS messes up our immune systems, endocrine systems, and nervous systems. The dysfunction in the autonomic nervous system (the part that regulates basic bodily functions) results in lower than normal blood volume and difficulty regulating our blood pressure and heart rate. Without adequate blood volume, our bodies have difficulty circulating enough blood to our hearts and brains, resulting in many of the symptoms we identify as ME/CFS.
How To Diagnose OI
As I mentioned above, many doctors diagnose POTS and NMH using a tilt table test (TTT), where the patient is strapped to a table that mechanically raises his or her head, a little at a time. Though the TTT is often considered the only way to diagnose these conditions, it has several drawbacks. It's very expensive, requires special equipment (and often traveling to a hospital or clinic), and is artificial, not reproducing exactly what happens in real life. It can also make patients very, very sick because you are intentionally triggering OI.
In contrast, an in-office standing test like Dr. Bell did for my son is quick and simple and can be done in any doctor's office in about 30 minutes or so. According to one study, it may actually be more accurate because it mimics real-life conditions, and the doctor can easily stop the test (as Dr. Bell did with my son) when the patient meets the criteria and/or gets too sick to continue (which is also meeting the criteria). Here are some very simple instructions for an OI standing test, developed by NASA, that you can take to your doctor. Just be aware that in some ME/CFS patients, OI can take a bit longer to show up and 10 minutes may not be enough. Dr. Bell's instructions and tips provide some extra guidance for this test, focused specifically on ME/CFS patients.
Finally, be aware that OI testing is not fool-proof. In fact, a study recently showed that OI testing only caught 47.5% of the cases of POTS in a single test. The study's authors recommended multiple OI tests. For this reason, it is very important for the doctor to observe and record the patient's reaction, as well as the data on heart rate and blood pressure. In my son's case, the purple feet, sweating all over, and general feeling of sickness would have proved he had OI, even if his HR was a few bpm below the criteria for POTS or his BP didn't fall quite enough to meet the criteria for NMH. Dr. Rowe said that a study in his clinic found that it took an average of 29 minutes for NMH to completely show up in ME/CFS patients. So, ask for the in-office test, but be aware of its limitations, and be sure the doctor observes your response to standing. And if you don't meet the criteria during testing, ask for another test on another day (share that study of the inaccuracy of OI testing with your doctor - it found the most accurate results with morning testing).
For more information (including more medical study references to share with your doctor), see my article on the ProHealth website, What is Orthostatic Intolerance and How to Diagnose It.
You may also find another blog post useful, Challenges in Diagnosing OI, which goes into even more detail on some of the problems you might encounter in trying to diagnose your OI and how to overcome them. It covers topics like what kind of doctor to see, how to conduct the test so it is most accurate, and tips for both doctor and patient.
How To Treat OI
The good news is that treating OI is fairly easy and often brings dramatic improvements in all ME/CFS (or fibro or EDS or Lyme) symptoms. It's been life-changing for both my son and I, allowing us to live more normal, active lives again with few post-exertional crashes. Two ways to treat OI are to increase blood volume and/or improve constriction of blood vessels to help circulate blood better. The easiest way to increase blood volume is to ingest HUGE amount of salt and fluids. I can't emphasize this enough! Sodium and fluids are critical for people with ME/CFS (check with your doctor first to be sure you're not one of the rare people with ME/CFS who has high blood pressure).
Next time you feel particularly sick or have a racing heart, drink a large glass of V-8 or other tomato or vegetable juice (lots of sodium!), Gatorade, or even a glass of water with a 1/2 teaspoon of sea salt in it (it's not so bad with lime in it). It won't cure you, but it helps. I always drink a big glass of V-8 juice before I go to the store to help keep my blood pressure and heart rate steady while I'm upright. My sons used to rely on Gatorade, but when the sugar and artificial colors started to adversely affect them, they switched to GU Brew tablets - they are sweetened with stevia, have no artificial colors or flavors, come in different flavors, and you just add them to water to create a balanced electrolyte drink. My sons also both took salt tablets while they had ME/CFS (one is recovered now and one still takes them). We have always used Thermotabs (we buy the 3-pack to save money) but I've also heard from many patients who are happy with SaltSticks - just be sure to take salt tablets with food because some people get nauseous taking them on an empty stomach. See additional links below for all of these products. This is just another crazy aspect of ME/CFS - the rest of the world is trying to reduce sodium intake while we need to intentionally try to make ourselves bloat!
Kids and teens often respond very well to a prescription medication called Florinef (fludrocortisone) (it rarely works well for adults, though it is worth a try). Its sole effect is to help the body hold onto more salt and fluids, and it is used in tiny amounts. Florinef, in combination with LOTS of salt and fluids, was like a miracle for my two sons. In 5th and 6th grades, our oldest son was bedridden over 50% of the time; he had a home tutor for two classes and made it to the other three about 60% of the time. After starting Florinef, he was able to return to school full-time in 7th grade, rejoin band, and play soccer again. For our younger son, whose ME/CFS was much milder, Florinef plus salt and fluids left him symptom-free about 90% of the time; he rarely even had post-exertional crashes after starting Florinef.
A couple of helpful hints with Florinef: you are supposed to start with a low dose and gradually increase, and you may not see any effect at all until you get to the right dose for you or your child. Some children I know started with too high a dose and had side effects but did well with it once they started low and gradually increased. We did that but were ready to give up on it after several months with no effect when Dr. Bell advised raising the dose one more time, to 0.2 mg (2 pills) daily - it was like someone had flipped a switch! When our son got older, he again increased his dose to 0.3 mg daily. Also, Florinef only works with large amounts of sodium and fluids. Our boys drank 2-3 liters of Gatorade every day (now the older one drinks about that much water with GU Brew in it). If one of them skips his electrolyte drink or doesn't drink enough, he feels worse the next day. Finally, Florinef alone isn't enough for some people; Midodrine (a vaso-constrictor) is sometimes added.
Unfortunately, Florinef almost always helps kids and teens and rarely works on adults, but there are other medications that may help adults (and kids, too), particularly low-dose beta blockers. Beta blockers work by blocking certain hormones in order to keep heart rate down and stabilize blood pressure. The first time I took one, my heart rate decreased about 30 bpm in the very first hour, bringing it down to normal levels for the first time in years! That alone allowed me to be more active without going over my limits and causing a crash/relapse. Starting beta blockers was another life-changing treatment for my older son and I (read more at the link). There are almost 40 different kinds of beta blockers available, in a wide variety of doses, so it can take some trial and error to find just the right one for you (always start with the lowest dose), but it is well worth the patience and persistence. More information in my post on beta blockers. They have allowed us both to be much more active, without post-exertional crashes. To learn more about WHY this works and how to use a heart rate monitor to help quantify your limits, read my post on Heart Rate and Post-Exertional Crashes in ME/CFS. Both my son and I now rarely crash from over-exertion and have greatly improved physical stamina. I can now walk for over an hour...with no crash after!
Some medications that you may take for other reasons help OI: for example, birth control pills and SSRIs (a type of anti-depressant) help increase blood volume and decongestants (particularly pseudoephedrine aka Sudafed) are vaso-constrictors. In fact, if I have something to do in the evening (when my beta blockers are wearing off), I sometimes take 2 Sudafed to help with OI.
Besides ingesting more salt and fluids and trying medications, some simple adjustments help, too, like moving your legs around when you have to stand still. I may look strange standing in the grocery store line flexing my leg muscles, standing on tiptoes, and otherwise fidgeting, but it helps to keep the blood from pooling in my feet. Just being aware of OI can help you. This is why you feel better when lying down than when standing up. Keep your feet elevated while sitting whenever possible (we now have 6 recliner seats in our family room, between chairs and couches!). You can also help to improve blood circulation and prevent pooling in the pelvis and legs without medication by wearing compression garments like knee socks (plain or in cool colors), tights (women's and men's) or compression shorts (Spanx work great!) - in addition to the links here, there are more at the end of this post for more options.
For more information, see my article on ProHealth, How To Treat Orthostatic Intolerance, and for more detail and lots of tips from experience on how to make treatments (especially Florinef and beta blockers) work best for you (they can all take some trial and error), see my blog post, Challenges in Treating OI.
More Information on Orthostatic Intolerance
A wonderful pediatric ME/CFS specialist at Johns Hopkins, Dr. Peter Rowe, first discovered OI in his pediatric ME/CFS patients and pioneered its treatment. There is an excellent article on diagnosing and treating OI written by Dr. Rowe that I highly recommend you read and share with your doctor. The article covers both diagnosis and treatments, including medications, sodium intake, and lifestyle changes. There is also an excellent summary of OI on Phoenix Rising that includes most of Dr. Rowe's information. Dr. Rowe is an amazing person - although he's rarely able to take on new patients, he's very willing to work with your own pediatrician or doctor through e-mail and phone calls. He spent hours on the phone with our sons' pediatrician, helping her to become comfortable treating OI in ME/CFS; she's now our own local expert! Though I highly recommend the article, especially for sharing with doctors, you can also watch Dr. Rowe's webinar on OI. And I wrote my own 2-part article on Orthostatic Intolerance for the ProHealth website that includes the research studies the information is based on, so you can share that information with your doctor (click References at the end of each article to view and print them) - Part 1 is on Diagnosing OI and Part 2 is on Treating OI.
And even with all that, I wrote two more blog posts on Orthostatic Intolerance because although almost all of us have some form of it, it's not always simple to detect it or to find exactly the right treatment(s) for you, so check out Challenges in Diagnosing OI and Challenges in Treating OI, both filled with loads of useful tips based on research and personal experience (from both my family and other patients).
Well, I think that covers the main points, but I urge you to read some of the extra information linked to here. Treating OI can result in great improvements for ME/CFS, fibro, EDS, and Lyme patients. It's one of the top areas that should be addressed, along with correcting sleep dysfunction and immune dysfunction.
Ironically, as I was sitting up on the couch typing this (in 2010, before I started beta blockers), I began to feel hot all over and sick, and I realized my own OI was acting up! I finished this post lying down, with my laptop on my lap. Once you understand OI and recognize its symptoms, you have more control over your ME/CFS. OI symptoms are your body's way of telling you that it can't circulate enough blood to the brain and heart and that you need to lie down. I think I'll also drink a V-8 before I go to pick my son up. Cheers!
NOTE: That last paragraph was written back in 2010. Now, with beta blockers, I am easily able to sit up all day without my symptoms increasing and no longer need that pre-store V-8, though I still sometimes use that strategy if I'm feeling poorly or will be especially active. With low-dose beta blockers, I can even exercise now! I have worked up to being able to manage up to 90 minutes (sometimes even 2 hours!) of walking or hiking at a time - wearing my heart rate monitor to stay below my AT. I can also do some weight training now, which has further improved my condition overall. Crashes due to over-exertion have become very rare for both my son and me.
For more information, see these resources:
Dr. Rowe's OI Summary Brochure (good for sharing with doctors)
My own 2-part article on Orthostatic Intolerance, published on ProHealth (also good for sharing with doctors, as it is footnoted with scientific references)
Heart Rate and Post-Exertional Crashes
Challenges in Diagnosing OI
Challenges in Treating OI
Tips on Using Beta Blockers and Finding the Right One for You
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