There is no single definitive test for diagnosing multiple sclerosis (MS). Instead, your doctor will perform a neurological examination and take your complete medical history. They’ll also perform diagnostic tests like MRI, evoked potentials, spinal fluid analysis, and a series of blood tests. An indicator of MS doesn’t show up in the blood, but blood tests are a very important piece of the puzzle.
To reach an MS diagnosis, a doctor must identify:
- damage in two distinct areas of the central nervous system
- that areas of damage developed at least one month apart
- that all other possible diagnoses are ruled out
Many medical conditions have symptoms similar to those of MS. Blood tests are an effective way to eliminate or confirm other diagnoses.
Tingling or numbness in the arms, hands, legs, and feet are common symptoms of both MS and Lyme disease. Lyme disease is a tick-borne infection. While not 100 percent accurate, ELISA and Western-blot blood tests can detect the presence of Lyme disease infection in the blood.
Although some symptoms are the same, treatment for each condition is different. Early stage Lyme disease often can be cured with a course of oral antibiotics.
Lupus is an inflammatory autoimmune disease that causes a wide variety of symptoms. Symptoms that lupus and MS share include:
- vision problems
Like MS, there is no single test for lupus. A blood test that is positive for antinuclear antibodies (ANA) or antithyroglobulin antibody may indicate lupus or some other autoimmune disease, but not MS.
Myasthenia Gravis (MG) is a disease characterized by weakness in nerve impulses that control movement. Symptoms similar to MS include weakness of the limbs and muscle fatigue. As with MS, heat and overexertion can make symptoms worse.
A blood test can detect serum antibodies to acetylcholine receptors. According to the Multiple Sclerosis Foundation, abnormally elevated serum levels of these antibodies are found in 80 percent of myasthenia gravis patients.
Devic’s disease is an immunological disorder that is strikingly similar to MS. The two conditions share many symptoms, including:
- blurred or lost vision
- bladder problems
A blood test called the NMO-IgG blood test will be negative in people with MS, but positive in 70 percent of patients with Devic’s disease, according to the Cleveland Clinic.
Certain vitamin deficiencies can cause symptoms that mimic those of MS. Vitamin B12, for instance, helps to maintain the central nervous system. MS is a demyelinating disease, and lack of B12 can cause demyelination.
Demyelination is damage to the protective covering (myelin) that surrounds nerve fibers within the central nervous system. Symptoms of vitamin B12 deficiency include numbness and tingling in the hands and feet, weakness, and fatigue. A simple blood test can check the levels of essential vitamins in your blood.
Minor pain, numbness and tingling, and fatigue may be early symptoms of rheumatoid arthritis (RA). As with MS, RA can’t be diagnosed with a single test. However, two blood tests can help doctors differentiate between MS and RA. A positive result from a rheumatoid factor (RF) blood test or a cyclic citrullinated peptide (CCP) blood test means that RA is a much more likely diagnosis than MS.
Since symptoms can come and go, and there isn’t one single test that provides a conclusive diagnosis, it can take a long time to diagnose MS. While the wait may be frustrating, each test will help eliminate or confirm other potential causes for your symptoms.
Getting the treatment you need depends on getting the right diagnosis. Blood tests are just one tool to help get you there.