Prevalence in a Causcasian population in Minnesota: about 1% of patients over 50 years of age
Features of LC-MGUS:
(1) elevated serum light chain concentration
(2) abnormal ratio of kappa to lambda light chains, indicating a clonal abnormality
(3) no obvious explanation (lymphoproliferative disorder, renal disease, etc)
(4) absence of IgH expression or other sign of conventional MGUS
Reference range for the kappa-to-lambda light chain ratio:
(1) normal population: 0.26 to 1.65
(2) "renal reference range: 0.37 to 3.1
Differential diagnosis:
(1) elevated serum light chain concentration with normal ratio in reactive lymphoproliferative disorder
(2) clonal increase in serum light chains associated with multiple myeloma, malignant lymphoma or other cause
(3) amyloidosis
Implications:
(1) increased risk for development of multiple myeloma or other lymphoproliferative disorder
(2) increased risk for development of a renal disease
A patient with LC-MGUS should have:
(1) light chain testing repeated at 6 months after diagnosis and then yearly thereafter
(2) screening for renal function periodically
