From the Guidelines
A kappa/lambda ratio of ≥100 or ≤0.01 is significant for considering myeloma, as it indicates a high risk of progression to active multiple myeloma. The normal serum free light chain ratio is 0.26-1.65, while the normal urine ratio is 1.0-5.2 1. A ratio less than 0.26 suggests lambda light chain predominance, while a ratio greater than 1.65 indicates kappa predominance. In multiple myeloma, this ratio is typically markedly abnormal, often showing either a very high ratio (kappa myeloma) or a very low ratio (lambda myeloma) 1. The degree of abnormality correlates with disease burden and can be used to monitor treatment response. An abnormal ratio combined with other findings such as elevated serum protein, bone lesions, anemia, hypercalcemia, or renal dysfunction strengthens the diagnosis of multiple myeloma 1. The ratio is particularly valuable in light chain myeloma where conventional serum protein electrophoresis may be normal. Regular monitoring of this ratio during treatment helps assess response, with normalization suggesting effective therapy and worsening ratios potentially indicating disease progression 1.
Some key points to consider when evaluating the kappa/lambda ratio include:
- The ratio is an independent prognostic factor for progression to multiple myeloma when it is outside the normal range (< 0.26 or > 1.65) 1
- A ratio of ≥100 or ≤0.01 is considered abnormal and indicates a high risk of progression to active multiple myeloma 1
- The ratio should be interpreted in conjunction with other clinical and laboratory findings, such as serum protein electrophoresis, bone lesions, and renal function 1
- Regular monitoring of the ratio during treatment can help assess response and detect potential disease progression 1
From the Research
Kappa Lambda Ratio in Myeloma Diagnosis
The kappa lambda ratio is a significant factor in considering myeloma diagnosis. According to the studies, the following ratios are considered significant:
- A kappa/lambda ratio of ≤1/7 or ≥9 yielded the highest diagnostic accuracy for multiple myeloma 2
- A kappa/lambda ratio of ≤1/16 or ≥16 also showed high diagnostic accuracy, but with a slightly lower area under the receiver operating characteristic curve 2
- A serum kappa/lambda ratio between 0.6 and 4.2 was found to have a high negative predictive value for ruling out multiple myeloma, but a lower positive predictive value for ruling in the disease 3
- A high serum free light chain ratio (sFLCR) at diagnosis was found to be a prognostic factor for poor survival in multiple myeloma patients 4
- A cytoplasmic kappa/lambda ratio of CD38-positive plasma cells between 0.59 and 4.0 was found to be a useful tool in distinguishing plasma cell myeloma from reactive plasmacytosis 5
Key Findings
- The kappa lambda ratio can be used to differentiate between monoclonal gammopathy of undetermined significance and multiple myeloma 3
- The ratio can also be used to predict response and survival in patients undergoing autologous stem cell transplantation 6
- Different studies have reported different cut-off values for the kappa lambda ratio, highlighting the need for further research to establish a standardized threshold 2, 3, 5