Why are there so many abnormal FLC results in patients with no malignancy?
Serum FLC levels are affected by rate of FLC production and rate of FLC removal (rate of glomerular filtration). Both of these factors can be affected in conditions other than malignancy. For example the rate of glomerular filtration can be reduced by a non-malignant condition such as non-AL amyloidosis, this will lead to elevated levels of serum FLC but normal FLC ratio. Also, production of polyclonal immunoglobulin is elevated in various autoimmune conditions and some bacterial infections, both have associated elevated levels of polyclonal FLC production which leads to elevated FLC levels with normal FLC ratios. An abnormal FLC ratio is highly diagnostic for B cell malignancy.
