Interpretation depends on the specific clinical indication and context.
Low serum levels of beta2 microglobulin essentially indicate decreased disease activity in conditions for which beta2 microglobulin is used as a
prognostic marker (multiple myeloma, lymphoma, leukemia) or the absence of such a disease process. However, low beta2 microglobulin levels are
never used to rule out a particular disease (eg, lymphoma) in the absence of other more definitive tests.
Increased serum beta2 microglobulin levels reflect increased activity of the disease process in question and can be an exquisitely sensitive
marker for this purpose in many hematologic disorders. The absolute value is less important than the historical values, except in certain
situations such as multiple myeloma, in which a value of less than 4 µg/mL was found to correlate with increased survival.
Increased urine beta2 microglobulin levels reflect tubular disorders of the kidney. In such cases, serum beta2 microglobulin levels are usually
normal, since the dysfunction is in tubular reabsorption.
Increased CSF beta2 microglobulin levels are seen in certain conditions such as multiple sclerosis, AIDS dementia complex, and meningeal spread
of hematologic tumors.