What is your threshold to diagnose light chain MGUS with only a slight elevation in the light chain ratio, in a patient without other CRAB symptoms and no M spike?  

Mild increase in kappa light chains can be a result of antigenic drift seen with the assay, in renal dysfunction both can go up but kappa may go up a bit more skewing the ratio. If a 24-hour urine with electrophoresis and immunofixation is negative and the rest of the work up is negative, would cont...

Marginally abnormal light chain ratio, usually kappa-predominant, is an extremely common referral in my practice, and my intuition has long been that most of these patients are well and don't need further workup or even long-term monitoring. This intuition is now supported by published data from the...

Long et al., PMID 36100605In the iStopMM cohort - light chain ratio new definition based on GFR when 45-60: 0.46 - 2.62, GFR 30-45: 0.48 to 3.38 and GFR<30 0.54 - 3.30.Higher age >70 got a new definition of higher reference range of 0.46 to 2.59.If elevated based on new reference ranges - then...

In the absence of CRAB and just slight elevation, would not consider a bone marrow. Would use the iStopMM.com formula to assist in the decision.