The path to a diagnosis of lupus can be a long and uncertain one. The average time between a person’s first symptoms and a definitive lupus diagnosis is six years. Regular testing and waiting to see whether more symptoms arise are unfortunate aspects of the process for many people. Other conditions may be suspected or even misdiagnosed before a person is finally diagnosed with lupus. In fact, 63 percent of people eventually diagnosed with lupus receive at least one incorrect diagnosis first. Some people have multiple chronic conditions, making it difficult for doctors to identify which is causing lupus-like inflammation.
How is lupus diagnosed?
Lupus is very difficult to diagnose. One challenge is that lupus can produce a huge range of symptoms that are different in each person. Another challenge is that there is not one conclusive test that proves lupus. Instead, there is a list of criteria developed by the American College of Rheumatology that doctors can use as a guide to decide whether to consider lupus as a potential diagnosis. The list of criteria includes:
It is possible to have lupus without having any of the signs or symptoms on this list, or only having one or two. In this case, the doctor may decide to wait and see whether other symptoms arise that point to lupus.
Apart from the list, there are other signs and symptoms doctors may consider as evidence of possible lupus. Brittle hair or hair loss around the forehead is common in lupus. The doctor may also check for Raynaud’s phenomenon, a color change (red, white, or blue) in the fingers upon exposure to cold.
If your doctor suspects lupus, they will likely perform tests to help confirm or rule out the diagnosis.
Tests and what they show
Some tests can provide proof of lupus-like inflammation, while others are performed to rule out different conditions. Again, no one test provides absolute confirmation of lupus.
The doctor will take a thorough history, asking about symptoms over time, family medical history, and possible exposures to toxins or infections. A clear picture may emerge from the medical history that will help a doctor assess risk factors that may strengthen the suspicion of lupus or rule out other conditions.
A complete blood cell count (CBC) taken from a blood sample can show whether you have low counts of red blood cells, white blood cells, or platelets. Low counts of any type of cell can be caused by lupus or by other conditions.
Antibodies are proteins produced by the immune system to mark and neutralize invading substances such as bacteria and viruses. In people with autoimmune diseases, the body produces antibodies that are anti-self, attacking the body’s own tissues. Antiphospholipid antibodies (also called lupus anticoagulant) are one type of antibody found in about 50 percent of people with lupus. Another is antinuclear antibodies (ANA), found in the blood of 97 percent of people with lupus, and common in other autoimmune conditions as well.
Blood tests can also be analyzed for proteins that indicate the presence of inflammation and any problems with liver or kidney function.
The doctor may also test blood clotting ability. Some people with lupus have abnormal blood clotting.
Healthy kidneys filter out all protein and cells. If proteins or red blood cells are found in the urine, this can indicate kidney damage that points to lupus nephritis (inflammation in the kidneys due to lupus).
The doctor may order a chest X-ray to check for inflammation in the lungs or an echocardiogram to make sure there are no abnormalities in the way the heart is beating.
During a biopsy, the doctor takes small sample of a tissue for lab testing. When lupus is suspected, the skin or kidney may be biopsied.
If you have experienced neurological symptoms, the doctor may perform a neurological exam. They will carefully examine your eyes and reflexes for signs of nerve damage. You will be asked to move your arms and legs in specific ways to test for weakness or lack of coordination. The doctor will test for loss of sensation by touching various parts of your body with a vibrating tuning fork, or sharp or dull items. The neurological exam provides an objective assessment of signs and symptoms that may suggest lupus or another condition.
Ruling out other conditions
Several other conditions can produce lupus-like symptoms. For this reason, lupus is sometimes referred to as “the great imitator.” The process of ruling out similar conditions is called differential diagnosis. To list just a few, conditions that may resemble lupus may include fibromyalgia, chronic fatigue syndrome, and autoimmune disorders such as rheumatoid arthritis (RA), scleroderma, or Sjögren’s syndrome.
Your doctor may be able to rule out many of these conditions quickly based on your medical and family history or simple blood tests. Other disorders may require time and repeated tests before they can be confirmed or ruled out. It is possible to have other diseases in addition to lupus, which may complicate the differential diagnosis and eventually result in multiple diagnoses.
What is the prognosis for lupus?
Most people with lupus live a normal average lifespan. Ten to 15 percent of those with lupus have shorter-than-average lifespans due to lupus complications, especially heart disease. Kidney disease and severe infections are other lupus complications that can become life-threatening.