+100%- “For the first time, physicians have access to technology which enables them to obtain blood volume measurement rapidly and with a high degree of precision.” – Daxor Corporation


Blood volume is often low in ME/CFS, but it was not until recently that an accurate and easy method of measuring it was possible.

Some people with Chronic Fatigue Syndrome (ME/CFS)  have been doing a bit more travel lately. It used to be that blood volume measurements were done at local hospitals, but with the advent of a more precise method some patients are traveling, sometimes hundreds of miles, to get to a medical center/research hospital that will do the test right. What do all these medical centers have in common? They have a Daxor BV-A 100  blood volume measurement machine. Blood volume measurement has never been done a lot even in ME/CFS, where blood volume is often quite low, and there’s a reason for that.  Past techniques required spending 4 to 8 hours at a hospital, and on top of that weren’t very precise.  Instead of actually measuring blood volume, they measured the ratio of red blood cells to plasma (higher ratio indicates higher thickness of the blood).  If you were missing equal amounts plasma and red blood cells, though, as many POTS and ME/CFS patients are, the test can indicate your blood volume is normal when it’s not.

News Report on the BVA-100

Checking out how much blood is flowing in your pulmonary artery can help, but that requires an invasive procedure involving the insertion of a catheter, and still doesn’t specifically measure circulating blood volume. With all these issues perhaps it’s not surprising that blood volume testing has mostly been done in research centers. Daxor has produced an instrument, however, that they assert provides quick, easy and very accurate blood volume measurements.

New Approach

Enter the Daxor Corporation’s test. The Daxor test uses a small amount of a radioactive isotope (iodine 131) injected to test blood volume. During the 1 1/2 hours following the injection, the concentration of the isotope in the blood is measured and compared to the concentration in known amounts of the blood. The measurement is repeated five times. The patient’s height and weight are used to determine normal blood volume values. Daxor states their machine accurately measures blood volume, red blood cell volume and plasma volume.  Its ability to distinguish between low red blood cell volume and plasma volume means it can identify which drugs (to increase red blood cells or plasma) will be most effective for people with low blood volume.

Since low blood volume seems to be almost a given in ME/CFS, why take the test?  One reason might be to determine which part of your blood (red blood cells or plasma) is low. Another is to monitor your blood volume and determine how effective treatments are at increasing it. A third might be simply to demonstrate to your doctor that you have a physiological issue.

The Test

Last year I had a brief talk with the research director of Daxor, Dr. Joseph Feldschuh, MD.  (The following is from memory.) Dr. Feldschuh noted that the blood volume findings in ME/CFS are unusual. Usually if your plasma volume drops, your red blood cells increase to compensate for that. Likewise, drops in red blood cell counts (anemia) are usually associated with increases in plasma volume. In ME/CFS, however, both are often low. Only the Daxor test, he asserted, measures both red blood cell counts and plasma volume accurately.  If your volume is low, drugs like epoetin alpha can increase red blood cell counts, and drugs like fludrocortisone (Florinef) can increase low plasma. (Other possibilities  exist.)


Running on empty during surgery is not a good idea and has probably contributed to numerous patients relapsing afterwards

While most doctors know nothing about blood volume, ME/CFS experts commonly prescribe IV saline as an aid to maintain blood volume and to help ME/CFS patients recover from stressful situations including surgery. Given the stresses put on the cardiovascular system during surgery, Dr. Feldschuh wasn’t at all surprised at all to hear that people with ME/CFS sometimes crashed after surgery. Some studies have found reduced blood flow to the brain is already present in ME/CFS, so it’s easy to see why some people with ME/CFS feel ‘loopy’ and unusually weak after surgery. The Daxor website proposes that ensuring normal blood volume levels are present would help avoid brain damage that can occur during surgery. Dr. Feldschuh noted that more women than men have ME/CFS or FM, and women tend to have higher rates of complications from cardiac bypass surgery.  Why that happens is not clear, but he suggested they may have a greater tendency toward low blood volume than men have. I know of one fairly healthy ME/CFS patient who relapsed badly after surgery, and who started to snap back only when she was given IV saline. She clearly had severe blood volume issues. Feldschuh proposed that blood volume measurements should be done prior to surgery  even in the healthy populations. Dr. Feldschuh himself provided a cautionary tale of surgery and blood loss. A  Daxor blood volume test revealed Dr. Feldschuh lost ten times as much blood as estimated by his anesthesiologist and surgeon during emergency surgery to repair a fractured hip.   (He used his own banked blood to make up the loss.)

Getting the Daxor Blood Volume Test

Most doctors will not have a Daxor machine, and you may need to go to a research hospital to find one. The Daxor Corporation lists almost sixty centers in the U.S. that have a Daxor blood volume measurement machine.

Health Rising is not affiliated with and or receive any funding from Daxor Corporation



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