Tests and diagnosis

By Mayo Clinic Staff

Monoclonal gammopathy of undetermined significance is usually detected during a blood test for another condition or other symptom, such as a nerve condition called peripheral neuropathy or an unexplained rash. The test, called serum protein electrophoresis (SPE), separates your blood proteins into five parts and can show any abnormal proteins as well as unusual amounts of normal proteins. Another test, the free light chain assay, is often done at the same time as the SPE, and it looks at the smaller parts of the M protein.

If your doctor detects monoclonal gammopathy, further testing may be ordered to determine what M protein your body is making and how much is being made. Your doctor also works to rule out other causes of elevated protein levels. Tests may include:

  • Blood tests. Tests to count the blood cells in your blood (complete blood count), to look for decline in kidney function (serum creatinine test) and to determine the amount of calcium in your blood (serum calcium test) can help rule out other types of monoclonal gammopathy, such as multiple myeloma.
  • Urine tests. Urine tests may be performed to determine if the abnormal protein is being released in the urine or to diagnose any kidney damage as a result of the protein. You'll likely need to collect your urine for 24 hours for this test.
  • X-rays. X-rays help your doctor look for bone abnormalities that may indicate another type of plasma cell disorder.
  • Bone marrow test. During a bone marrow test, your doctor uses a hollow needle to remove a portion of your bone marrow from the back of one of your hipbones. The bone marrow is then analyzed to determine what percentage of plasma cells it contains. This test is generally only done when doctors suspect that someone is at risk of developing a more serious disease, or in people with unexplained anemia, kidney failure, bone lesions or high calcium levels.
May 17, 2013