Richard commented on the (poor) relationship between the L-index (or better, the T-index) and triglyceride concentration. Whether called the L- index or T-index, it is really an estimate of turbidity and not necessarily lipemia. The poor correlation between this L- or T-index and triglyceride has been noted in the literature (don't have time to find citation right now) and I have data as well. I am not sure to what extent the poor correlation is due to variability of triglyceride content in lipoproteins or to non-lipoprotein sources of turbidity (platelets, cell fragments, other?). Probably both. I think the interference in most assays that are affected by "lipemia" is due to turbidity (spectral interference) and the degree of interference would be related fairly well to the index. However, some assays may have interference from lipoproteins by analytes or reagent components dissolving in the lipoprotein particles.
-Jim