What Goes on During an ANA Test
An ANA can be found in
I’m Dr. Bob Lahita, Chairman of Medicine at Newark Beth Israel Medical Center and Professor of Medicine at the University of Medicine and Dentistry of New Jersey, and I’m going to talk to you about an ANA test.What exactly is an ANA test? An ANA test is an antinuclear antibody test. In the old days, it used to be called a FANA or F-ANA test, florescent antinuclear antibody test. The ANA is generally done by drawing a sample of blood, taking away the blood cells and saving the serum. The serum can be overlaid on a variety of cells that can include rat liver, mouse kidney or cultured cells such as HeLa cells or other kinds of cells that have big nuclei. The nucleus of the cell stains if there’s antibody in your blood that is directed against the nuclear material of cells.Now, the problem with this is it’s not very sensitive and it’s not very specific. An ANA can be found in people over the age of fifty, and it can be found in pregnant women. It can be found, to be sure, in people with autoimmune diseases, and that’s why it’s done. But, I use a cutoff of a titer one to eighty, which means if I dilute the blood out, your blood, eighty times it will be diluted and staining of the nucleus will go away. I consider that negative. Anything above one to eighty will be recorded by your doctor’s lab or the hospital’s lab as being positive.Now, patients with diseases like systemic lupus will have titers of one to twenty-five sixty, which means one to two thousand five hundred sixty times that blood sample has been diluted, but it’s still positive. That is, it is still staining nuclei from cells. So, that’s what’s called a positive ANA test.Now, the positive ANA test as mentioned is neither specific nor very sensitive. It is commonly found in normal people and people with conditions that are suggestive of autonomic disease like rheumatoid arthritis, lupus, Sjogren’s, polymyositis. It can be found in a variety of conditions and is not to be considered the hallmark of any one particular disease.For more information about this, go to About.com.