View Full Version : How reliable are blood tests?
Today primary care drew tons of blood. He said if it isn't conclusive he will send me to a specialist.
We are thinking Lupus because of long history of butterfly rash (which until today he seemed to ignore!)
Today I went in with Livedo reticularis...a really bad case of it all over my back. (testing me for thrombocytopenia)
I've had alternating bouts of GI problems (blood and mucus) and pain, and very severe joint pain over the last year.
I'm very nervous that the tests won't be conclusive and I won't know what's going on.
I've had joint pain for many years and have been told I have fibromyalgia. The problem is that I can't get a doctor to take my pain seriously.
I'm actually hoping for some kind of true dx so someone will take my aches and pains seriously.
Fibromyalgia is a blow - off to most docs who just tell me to exercise.
I'm getting tired and depressed.
I had to take a sit down job (I'm a nurse) due to the increasing joint pain.
Guess what I'm really asking is do they HAVE to have proof from blood test to give a diagnosis?
Sounds dumb, I guess, me being a nurse. But I really don't know.
It's not that I WANT to have lupus.
I just wonder what it takes to get a doctor to take the pain seriously.
I can't take the normal arthritis meds because they all make my GI bleed.
11-14-2006, 06:53 PM
This is a hard question, because the accuracy of blood and other lab tests depends to some extent on the accuracy of the lab where they are processed. If the samples were properly collected and stored, and the lab itself is reliable and thorough, then yes, in most cases the results themselves are accurate. In lupus, it's often not the accuracy of the results that is an issue, but how these results are interpreted.
Lupus can be tricky to diagnose, bucause there is no one specific test that will diagnose it with absolute surety. So the diagnosis is based on a combination of clinical signs and symptoms, and the results of various laboratory tests. Even abnormal lab tests results, by themselves, are generally not enough to diagnose lupus unless the clinical symptoms are consistent.
The American College of Rheumatology has developed a set of 11 criteria to describe the symptoms and lab findings most specific to lupus. The presence of four or more criteria support the diagnosis of lupus, while the presence of three suggest lupus is probable. The criteria do not all have to be present at the same time in order to count.
1) Malar Rash. The "butterfly rash" is present in about 50% - 75% of lupus patients. It is a red, sometimes raised, rash over the cheeks and the bridge of the nose, but not affecting the folds of the nose. In some people it is more like a flush. Other conditions including rosacea can cause a similar rash, so a biopsy may be needed to confirm the rash is lupus related.
2) Discoid Rash. These are red, raised patches, usually coin shaped, that may leave scars. The lesions often have a scaly, "warty" appearance, They generally affect the face, scalp and ears, the arms, back and chest, and are less likely to involve the legs.
3) Photosensitivity. Reaction to sunlight,resulting in the development of or increase in skin rash
4) Oral Ulcers. Ulcers affecting the mucosal lining of the mouth or nose, usually painless, observed by a physician.
5) Arthritis. Nonerosive arthritis involving two or more peripheral joints (arthritis in which the bones around the joints do not become destroyed). Peripheral joints include the hips, shoulders, knees, elbows, wrists, ankles, and the small joints of the fingers and toes.
6) Serositis. Pleuritis or pericarditis (inflammation of the lining of the lung or heart). This can be documented by a convincing patient history, or by evidence on physical examination of either a pleural rub or a pericardial effusion.
7) Renal Disorder. Excessive protein in the urine (greater than 0.5 gm/day or 3+ on test sticks) AND/OR cellular casts (abnormal elements in the urine, derived from red and/or white cells and/or kidney tubule cells). Generally, the tests must be abnormal on at least two separate instances to be considered.
8) Neurologic Disorder. The only two neurological problems considered specific for lupus are seizures (convulsions) AND/OR psychosis in the absence of drugs or metabolic disturbances which are known to cause such effects. Cognitive dysfunction, ataxia, loss of coordination, or other neurologic problems are not specific to lupus and do not satisfy the criteria. The seizure and /or psychosis must be observed or documented in the patient's medical records.
9) Hematologic Disorder. There are four blood disorders which satisfy this criteria. Autoimmune hemolytic anemia (destruction of red blood cells caused by abnormal immune response) OR leukopenia (white blood count below 4,000 cells per cubic millimeter) OR lymphopenia (less than 1,500 lymphocytes per cubic millimeter) OR thrombocytopenia (less than 100,000 platelets per cubic millimeter). The leukopenia and lymphopenia must be detected on two or more occasions. The thrombocytopenia must be detected in the absence of drugs known to induce it. The only form of anemia whih satisfies the criteria is hemolytic anemia - iron deficiency or other forms of anemia are not included.
10) Antinuclear Antibody. Positive test for antinuclear antibodies (ANA) in the absence of drugs known to induce it.
11) Immunologic Disorder. There are four immunologic disorders (all are detectable through blood testing) which satisfy the last criteria - Positive anti-double stranded anti-DNA test OR positive anti-Sm test OR positive antiphospholipid antibody such as anticardiolipin or lupus anticoagulant OR false positive syphilis test (VDRL).
Hope this helps!
Thank you for such a thourogh reply.
I appreciate it sooo much.
I guess if the results are inconclusive I'll just be a squeeky wheel until someone listens.
11-15-2006, 03:35 AM
I feel for you. I have SLE and it literally took years and years for me to get dx. I am 47 years old and have been on medications for the past 12 years. For me the illness did not show up in my blood until I was very sick with it. When I got diagnosed I had nearly all of the symptoms for Lupus and Sjogrens. They don't only go by lab work to diagnose you though. Marycain shows the list of Criteria. I hope that you get the answers as to what is going on with you.
11-15-2006, 01:12 PM
Diagnosis is tough, my rheumy keeps telling me. She's been great, though. I hope you find someone who listens to you, Kay. Keep being the squeaky wheel! My diagnosis is not 'officially' Lupus, but conditions are significant enough that the rheumatologist is treating it as such anyway. I have a related question. As more blood tests are done over time, can I expect that some of the other tests for immunologic disorder are likely to be positive? (Mary, you list those in #11 of the criteria.) Is it likely other symptoms will occur over time? I often hear that Lupus will go into remission and when it comes back, it may come back with new symptoms. It's been about 6 months since the unofficial 'diagnosis' and I'm still just not clear on some things.
11-15-2006, 02:35 PM
I think it's different for every person, and very difficult to predict. In some long term follow up (over a five year period) studies of patients with "probable lupus", only about 33% eventually fulfilled the ACR criteria for systemic lupus. In some the initial lupus-like symptoms either subsided, or did not progress any further, others were diagnosed with other illnesses, and some remained either probable lupus or lupus-like disease. So it's important to find a doctor who is willing to treat your symptoms aggressively as they arise, and monitor you for any changes in your symptoms or labs. Not everyone with lupus gets worse, so it is not a "progressive disease" in the sense that Parkinsons, Huntingdons and some of the neurologic diseases are. Many people with mild lupus do well with just NSAIDS or plaquenil and never develop severe lupus or organ involvement.
Remember, too, that the only one of the immunologic criteria unique to lupus is anti-sm, and only about 30% of lupus patients have this antibody. Anti-ds-dna is more common, but can occur in some conditions other than lupus. Antiphopholipid antibodies and false positive syphilis test can both occur in Primary Antiphosolipid antibody Syndrome as well as lupus. So many rheumatologists look more at the pattern of your clinical symptoms than the immunologic criteria. And other lab tests which aren't included in the criteria can be important diagnostic tools, especially sed rate, c-reactive protein, and serum complement levels. So your doctor may be considering these test results as well.
Hope this helps!
11-16-2006, 12:20 PM
Thanks...good info and it does help. I have many books and much info bookmarked on the web, but sometimes it all just runs together. It's helpful to have an easy summary. My rheumatologist is good and she's really focused on symptoms. She's told me many times not to get 'hung up' on the official diagnosis thing, since she's going to treat for symptoms anyway. I like that and it makes sense. She said "we'll call it lupus, 'cause that's easier to say than connective tissue disease!"
12-06-2006, 10:19 AM
I guess that whether or not blood tests are needed to prove Lupus depends on the physician doing the diagnosing, but diagnosis should not be based completely on the results of blood tests. There can be false positives, negatives, and interpretations. If you have lupus but are in "remission" all the blood tests would be neg. Like mine, but I still have symptoms.
I'm not a doctor, but based on your symptoms I'd say it is highly possible that you have Lupus.
Are you in line to see a rheumatologist? That is where I got my diagnosis, and my sx are nowhere near as complex as yours.
In fact, I went to the rheumatologist thinking I had fibromyalgia, and she ran all kinds of tests before giving any diagnosis.
I understand the sentiment of not wanting to have Lupus, but at the same time the diagnosis would help everything else make sense. It's tough to tote around a bunch of symptoms and disorders and have no diagnosis. A diagnosis also gives you a direction to go.
BTW, I am also a nurse. I had a very basic undestanding of Lupus until I was diagnosed with it, and I'm still learning.